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International Journal of Pediatric Otorhinolaryngology 78 (2014) 1716–1725
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International Journal of Pediatric Otorhinolaryngology
journal homepage: www.elsevier.com/locate/ijporl
Hear here: Children with hearing loss learn words by listening
Joyce Lew a,b,*, Alison A. Purcell b, Maree Doble b, Lynne H. Lim a
National University Health System, National University of Singapore, Department of Otolaryngology, NUHS Tower Block, Level 7, 1E Kent Ridge Road,
Singapore 119228, Singapore
The University of Sydney, Discipline of Speech Pathology, Faculty of Health Sciences, P.O. Box 170, Lidcombe, NSW 1825, Australia
Article history:
Received 7 April 2014
Received in revised form 20 July 2014
Accepted 22 July 2014
Available online 12 August 2014
Objectives: Early use of hearing devices and family participation in auditory-verbal therapy has been
associated with age-appropriate verbal communication outcomes for children with hearing loss.
However, there continues to be great variability in outcomes across different oral intervention
programmes and little consensus on how therapists should prioritise goals at each therapy session for
positive clinical outcomes. This pilot intervention study aimed to determine whether therapy goals that
concentrate on teaching preschool children with hearing loss how to distinguish between words in a
structured listening programme is effective, and whether gains in speech perception skills impact on
vocabulary and speech development without them having to be worked on directly in therapy.
Method: A multiple baseline across subjects design was used in this within-subject controlled study. 3
children aged between 2:6 and 3:1 with moderate–severe to severe-profound hearing loss were
recruited for a 6-week intervention programme. Each participant commenced at different stages of the
10-staged listening programme depending on their individual listening skills at recruitment. Speech
development and vocabulary assessments were conducted before and after the training programme in
addition to speech perception assessments and probes conducted throughout the intervention
Results: All participants made gains in speech perception skills as well as vocabulary and speech
development. Speech perception skills acquired were noted to be maintained a week after intervention.
In addition, all participants were able to generalise speech perception skills learnt to words that had not
been used in the intervention programme.
Conclusions: This pilot study found that therapy directed at listening alone is promising and that it may
have positive impact on speech and vocabulary development without these goals having to be
incorporated into a therapy programme. Although a larger study is necessary for more conclusive
findings, the results from this preliminary study are promising in support of emphasise on listening skills
within auditory-verbal therapy programmes.
Crown Copyright ß 2014 Published by Elsevier Ireland Ltd. All rights reserved.
Hearing loss
Speech perception
1. Introduction
Hearing loss (HL) is the most common birth anomaly, affecting
1–3 of every 1000 newborns in developed societies [1–4].
Congenital hearing loss impacts language learning [5,6], speech
development [5,7], psychosocial development [8–10], literacy
[6,11,12], academic success [13] and employment outcomes
* Corresponding author at: National University of Singapore, Department of
Otolaryngology, NUHS Tower Block, Level 7, 1E Kent Ridge Road, Singapore 119228,
Singapore. Tel.: +65 6772 5370; fax: +65 6775 3820.
E-mail addresses: [email protected] (J. Lew), [email protected]
(A.A. Purcell), [email protected] (M. Doble), [email protected]
(L.H. Lim).
[13–16]. As a result, hearing loss is identified as one of the most
costly lifelong conditions [16]. The sequelae of lifelong events
affected by hearing loss seem to begin in-utero [17,18]. Babies with
typical hearing are born with skills that facilitate language
development from the first moments of life [19,20]. At birth,
infants have preferential attention to their own mother’s voices
[21], human speech sounds over nonspeech sounds [19], as well as
an ability to recognise their own native language spoken over other
languages [22]. Newborns with typical hearing are also able to
perceive fine acoustic differences between individual speech
sounds [21,23,24]. Where children are born with hearing loss,
their ability to access speech acoustic information for detecting
and discriminating between speech sounds is diminished. A recent
cortical study on the auditory pathways of children born with
0165-5876/Crown Copyright ß 2014 Published by Elsevier Ireland Ltd. All rights reserved.
J. Lew et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 1716–1725
hearing loss report correlation between increased length in
auditory deprivation and decreased likelihood in achieving normal
cortical responses to sound through the use of assistive hearing
devices [25].
1.1. The importance of early intervention
The need to minimise the lifelong impact of permanent
sensorineural hearing loss has resulted in a number of important
changes to the management of young children with hearing loss.
Increasingly widespread implementation of newborn hearing
screening has enabled the early detection of hearing loss whilst
advances in amplification devices have enabled most children born
with hearing loss to have auditory access to speech sounds. Best
practice for newborns with permanent hearing loss currently
involves the detection of hearing loss by one month of age,
amplification by 3 months and attendance at early intervention by
6 months [26–28]. This is frequently referred to as the 1-3-6
There is a spectrum of early intervention choices available to
parents, from programmes that aim to teach children how to
communicate manually to programmes that teach children how to
communicate orally (refer to Schwartz [29] for a description of the
main options). For parents who would like their child with hearing
loss to learn to speak, an early intervention choice that has been
gaining in popularity is Auditory-Verbal Therapy (AVT) [30]. With
an emphasis on the use of appropriate hearing technology for
auditory stimulation, the fundamental goal in AVT is for children to
use hearing as the primary sensory modality in developing spoken
language [31]. AVT focuses on creating listening experiences so
that the child’s newly acquired auditory potential is optimally used
as they learn to process verbal language and speak [32].
Children enrolled in AVT have been reported to be successful
at achieving age-appropriate verbal communication outcomes
[33–35]. A longitudinal outcome study of children enrolled in an
AVT programme by Dornan et al. [33,36] has shown that language
growth with each year of therapy was comparable with that of
normal hearing peers matched for language age, gender and
socioeconomic status. These findings were supported by a more
recent longitudinal study that examined the language development of children who received intervention in accordance with
1-3-6 guidelines [35]. In this study, Fulcher et al. found that 90% of
children born with hearing loss achieved age-appropriate speech
and language outcomes by 3 years of age [35]. Outcome studies of
AVT have been important in supporting the overall efficacy of AVT
programmes in the current drive towards evidence-based practice.
In order for such positive outcomes to be achieved across all
AVT programmes, it is important to have evidence to support
practitioners in the use of clinical techniques as well as prioritising
goals that drive each therapy session. Rhoades [30] raised concerns
regarding the lack of research evidence in supporting the process of
AVT; and noted the need for data to answer critical questions such
as which clinical strategies used in AVT programmes are more
efficient than others. The current guiding principle for goal setting
in AVT indicates that practitioners are to follow the developmental
patterns of typical children covering the areas of audition, speech,
language, cognition and communication [31]. With respect to
audition, there are a number of published developmental
hierarchies used by AV practitioners to develop and refine a
child’s listening skills. Some examples include the ‘Listening Skills
Scale for Auditory-Verbal Therapy (LSSAVT)’ [32], ‘Targets for
Auditory/Linguistic Learning’ [17], the ‘St. Gabriel’s Curriculum’
[37] and the ‘Listen Learn and Talk’ [38]. While these audition
hierarchies are widely used and central to therapy planning, no
known outcome study has been published on the efficacy of
designing a therapy programme based on these hierarchies.
Speech perception is a significant component of many widely
used audition hierarchies, yet little is known regarding the efficacy
of speech perception intervention with infants and preschool
children with hearing loss. Research evidence is available only for
the efficacy of speech perception intervention with adults and
school-aged children. Although these intervention studies
reported positive outcomes [39–42], their applicability to preschool children is limited because all of these programmes require
participants to have prior linguistic and letter-to-sound knowledge
in addition to being literate. Moreover, the programmes tracked
the development of speech perception skills without measuring
the development of other aspects of verbal communication skills
such as vocabulary development and speech intelligibility, thereby
failing to demonstrate any improvement in functional skills as a
result of improved speech perception or auditory development.
It is important to understand the essential role that speech
perception intervention plays in AVT as teaching listening is one of
its key elements. Several studies have found correlation between
development of early speech perception and later vocabulary skills
in young children with normal hearing [43–45]. In addition,
prospective studies of typically developing infant speech perception and early language abilities report that infant speech
perception skills accurately predict low vs normal language
function up to 8 years of age [46–48]. These findings are exciting
for children with hearing loss. If speech perception skills during
infancy can predict language status in later childhood, perhaps
early intervention of poor speech perception skills can intercept
the course of delayed or impaired language development. In order
to determine whether there is positive correlation between speech
perception skills and vocabulary in pre-schoolers with hearing
loss, Desjardin et al. [49] designed a speech perception test that is
based on the repetition of nonsense syllables. This cross-sectional
study found significant correlation between speech perception and
vocabulary skills, thereby supporting the hypothesis that speech
perception intervention may have a positive impact on the
vocabulary of preschool children with hearing loss who are
learning spoken language. An intervention study with school-aged
children by Paatsch et al. [50] analysed the effects of speech
production intervention as well as vocabulary intervention and
found a causal impact on speech perception and reading
development [50]. Although the impact of speech perception
intervention on speech production and vocabulary skills cannot be
ascertained from this study, it seems there is a relationship
between development in speech production and/or vocabulary
skills with development in speech perception in older children
with hearing loss.
Recent studies have found discontinuity between development
in speech perception skills and early word learning for young
preschool children with normal hearing [51–53]. These studies
suggest that the processing demands of linking words to meaning
are so great for the novice word-learner that they have difficulty in
attending closely to the fine phonetic detail that is available in the
speech signal. If children with normal hearing who are born ready
for speech perception have difficulty attending to fine acoustic
detail when they first begin learning words, what is the course of
word learning in children with hearing loss who are still in the
process of learning speech perception? A recent study on word
learning processes in preschool children using cochlear implants
who were enrolled in auditory-verbal programmes by Walker and
McGregor [54] found that the children demonstrated delay in word
learning despite early cochlear implantation. In comparison with
typically developing peers, the children with hearing loss had
difficulty with fast-mapping which is the word learning process of
linking a word to its referents after only a few exposures [54].
Inferential fast-mapping whereby novel words were not directly
marked by social or linguistic cues were particularly difficult for
J. Lew et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 1716–1725
below, which is aimed specifically at determining how consistent
the participant is with word pairs that they had already achieved
criterion in therapy.
children with hearing loss, which may explain why children with
hearing loss tend to learn fewer words incidentally than children
with typical hearing [55]. Given the established link between
speech perception and later language development in children
with typical hearing, it is of interest to determine if children with
hearing loss can learn words automatically in the process of
learning better speech perception skills without vocabulary having
to be incorporated into goals of auditory-verbal therapy. The
answer to this question is important for professionals working
with preschool children with hearing loss as it may allow the
course of word learning to be sped up through more successful
inferential learning.
In addition to vocabulary and language development, intact
speech perception skills are necessary for speech development,
with hearing loss being a recognised causal factor in speech
difficulties [56,57]. In spite of early identification and intervention
for children born with hearing loss, a longitudinal study of speech
development by Moeller et al. found that this group of children
continues to have overall delayed speech development with
particular difficulty in fricative and affricate production [7]. This
study demonstrated that although early intervention has enormous benefits for children, listening and the development of skills
associated with this sense continue to be difficult for children with
hearing loss [7]. Noting the lack of intervention studies on the
impact of speech perception intervention on speech production,
Moeller [9] also suggested the implementation of intervention
studies to determine whether focused listening practise could
impact on speech development.
Since there have been no known studies to support an
assumption that word learning and speech development automatically follows improved speech perception skills, it is important to
monitor whether they develop alongside speech perception skills
for children with hearing loss. The aims of this study were
therefore: (1) to determine whether speech perception intervention for preschool children with hearing loss is effective, (2) to
determine whether development in speech perception skills has
positive impact on vocabulary development, and (3) to determine
whether development in speech perception has positive impact on
speech development.
1.2. Speech Perception Education and Assessment Kit (SPEAK)
1.2.1. SPEAK-Intervention
The intervention programme consisted of 11 levels of difficulty
and commenced at the child’s performance level as determined by
the SPEAK-Baseline. At each intervention session, the child worked
through 2 sets of cards (A and B) with a parent as well as the
therapist. There were 2 pairs of cards in each of sets A and B, as
illustrated in Fig. 1 below.
Intervention commenced with the first pair of words in set A.
Each of the picture cards were hidden in a variety of objects (e.g.,
envelope, box, stuck to the bottom of a toy, etc.) and presented one
at a time through audition in an auditory exposure phase. This
phase involved the therapist taking an object that contained a
picture card, saying the target word and having a peep at the
picture in the object. The therapist would then turn to the child’s
parent who will provide the child with another opportunity to
listen to the target word without seeing the corresponding picture
card in the same manner. The child is finally given an opportunity
to open the object to see a picture card that represents the word.
While the child looked at the picture, the therapist said 3 short
phrases with each phrase comprising the target word. This process
is repeated for the second picture card, yielding two target words
for each child to practice perception with their parent. In the
practice phase, both cards were first put in front of the parent
within the child’s visual field, and the parent was asked to listen to
the therapist say one of the words and point to the associated
picture. This followed with the child having a turn at listening to a
word and attempting to point at the corresponding picture. Both
the parent and the child took turns practicing 5 times each before a
new pair of cards was presented using novel objects and worked on
in the same way. The 2 pairs of cards from Set A yielded a therapy
score out of 10, which allowed the therapist to determine whether
pass criterion had been reached. If the child was accurate for 8 or
more times, Set B of the intervention session comprised of words
from the next level of the intervention programme. Where the
child did not meet the pass criterion with Set A of the therapy
session, Set B comprised of a different set of words at the same level
of difficulty as that of Set A. Feedback was given each time after the
child and parent pointed to a card in the practice phase. When a
mistake was made, the child was shown the correct picture while
he heard a repetition of the target word. The parent and child were
then be given a token reinforcement each time after feedback,
In order to answer these questions, the Speech Perception
Education and Assessment Kit (SPEAK) programme was developed.
The work of Boothroyd [58] which depicts the spread of acoustic
information available to listeners to distinguish between speech
sounds was applied in the development of this 10-level intervention programme. The programme consisted of the (i) SPEAKIntervention, (ii) SPEAK-Baseline as well as (iii) SPEAK-Probes. The
SPEAK programme commenced at level 1 with discriminating
between long and short words that have differing numbers of
syllables (e.g., ‘aeroplane’ vs ‘sun’), followed by single-syllabic
words that have maximal differences in acoustic information
available for the listener to discriminate between them (e.g., ‘bus’
vs ‘cloud’) in level 2. The latter stages of the programme consist of
single-syllabic words that sound increasingly similar and are thus
more difficult to discriminate between. The difficulty was
increased by systematically decreasing the amount of acoustic
information that was available to the listener to discriminate
between each pair of words until level 10 which consists of words
with minimal acoustic information between the word pairs.
Although the level of speech perception difficulty are the same
across sections of the SPEAK programme (Intervention, Baseline
and Probes), word pairs used in each section of the SPEAK
programme were not repeated in other sections of the programme.
The exception to this is the consistency probe, further described
Fig. 1. Illustration of each intervention session.
J. Lew et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 1716–1725
whether or not they picked correctly. At the end of each 30-min
intervention session, the parent was given materials for home
follow-up the next day. Follow-up consisted of a fresh set of cards
at the highest level that the child had reached pass criteria and
another set of cards at the next level at which the child had not
achieved criterion. The intervention programme terminated after
18 sessions with the therapist or after the child achieved pass
criterion at level 10 of the intervention programme, whichever
occurred first.
1.2.2. SPEAK-Baseline
The SPEAK-Baseline determined the level at which the child
commenced the intervention programme as well as change in
speech perception skills before and after the intervention
programme. The baseline was constructed to match the 10 speech
perception levels of the SPEAK-Intervention programme; the higher
the level the finer the acoustic differences between the words. Each
level of the SPEAK-Baseline consisted of four picture cards which
were individually presented to the child as the therapist verbally
labelled them without allowing the child to lip-read. The child then
listened to a target word and pointed to the picture that he thought
represented the target word for 10 trials at each level of the test. The
SPEAK-Baseline yielded a score representing the number of times
the child pointed correctly out of a maximum score of 100, as well as
a skill level between 0 and 10. It was administered before the
intervention programme to determine the level at which each child
should commence the SPEAK-Intervention programme. The skill
level was the highest level out of the 10 levels of the test at which the
child scored at least 8 out of 10. The skill level is also the level at
which participants commence SPEAK-Intervention. Token reinforcers were used to keep the participants engaged throughout the
baseline measures. SPEAK-Baseline was re-administered after the
SPEAK-Intervention phase to determine any changes in speech
perception levels.
1.2.3. SPEAK-Probes
Three progress probes were incorporated into the SPEAK
programme in order to examine generalisation across theoretically
related responses as well as to attain within-subject experimental
control data. The first was the generalisation probe which
consisted of 4 words represented by picture cards that were at
the same level of difficulty as the child’s speech perception skill
level. Words used in the generalisation probe were novel to words
used in both the SPEAK-Intervention programme and the SPEAKBaseline. This probe was designed to provide information on how
well the child generalised their speech perception skills from
words used in the intervention programme to discriminating
between untaught words. The second progress probe was the
control probe which consisted of four novel words that were three
levels above the child’s perceptual level. Participants’ performance
on the control probe should ideally remain fairly constant
throughout their participation in the intervention programme.
The final probe, the consistency probe, comprised of 4 words at
perceptual level that the child had been exposed to during the
speech perception intervention programme. The consistency probe
was designed to provide information on how consistent the child
was with their speech perception skills with familiar words
encountered during therapy at their skill level.
With each probe, the child was presented with four picture
cards in the same way as in the SPEAK-Baseline and then asked to
point to a card labelled by the therapist for 10 trials.
Review Board (Reference Number DSRB-D/11/016) and the
University of Sydney Ethics Committee for research involving
human subjects (Protocol Number 05-2011/13708).
2.1. Participants
Participants were recruited from the AVT programme at the
National University Hospital (Singapore) over a period of 12
months. The recruitment criteria required participants to be aged
between 2:6 and 4:0, have bilateral permanent sensorineural
hearing loss of at least moderate severity and be consistent users of
hearing aids and/or cochlear implants. In addition, participants
must score below the highest category score of four on the lowverbal version of the Early Speech Perception Test (ESP) [59]. Given
the multilingual setting in Singapore, participants may be bilingual
but use English as the main language of communication at home.
All children who had been formally diagnosed with other
impairments in addition to hearing loss were excluded from this
study. From a total of 24 children aged between 2:6 and 4:0
attending the National University Hospital AVT programme, only 4
met these inclusion criteria. The families of 3 of these 4 children
agreed to participate in the study. Of the 20 children who did not
meet the inclusion criteria; one was excluded because of poor
hearing aid compliance, 7 were excluded because English was not
the main language spoken at home, 10 were excluded because they
had multiple disabilities and 3 were excluded for achieving the
highest category on the low-verbal version of the ESP. The details
of each participant’s age at recruitment, severity of hearing loss as
well as the type of listening devices used are summarised in
Table 1.
2.2. Outcome measures
A battery of pre- and post-intervention assessments was
administered before and after the intervention programme was
implemented, to evaluate the participants’ progress in speech
perception, vocabulary and speech development. These tests are
outlined below.
2.2.1. Speech perception
The low-verbal version of the Early Speech Perception Test
(ESP) [59] was used before and after SPEAK-Intervention to capture
any changes in speech perception skills. In addition to the ESP
being administered pre- and post-intervention, the SPEAK-Probes
were administered throughout the study. The SPEAK-Baseline was
administered to determine the starting level for the SPEAKIntervention. Both trained and untrained speech perception skills
were monitored using three different progress probes to examine
generalisation of skills while maintaining experimental control.
Further information regarding the generalisation, control, and
consistency probes can be found under SPEAK in the introduction.
2.2.2. Vocabulary
Vocabulary was assessed using Versions A and B of the Peabody
Picture Vocabulary Test – Fourth Edition (PPVT-4) [60] as well as
the 2500+ Words List [61]. The PPVT-4 was selected to provide
standard scores, percentile ranks and growth scale values (GSV).
Table 1
Participant age, severity of hearing loss and listening devices used.
Age at
Severity of
hearing loss
Listening devices
Bilateral cochlear implants
Bilateral hearing aids
Bilateral hearing aids
2. Method
This study was conducted in accordance with ethical standards
stipulated by the National Healthcare Group Domain Specific
J. Lew et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 1716–1725
The GSV score was important as it provides evidence of change in
vocabulary growth. This allowed any increase in vocabulary to be
classified as either within expected developmental growth or
exceeding typical developmental growth.
The 2500+ Words List is a parent-administered receptive
and expressive vocabulary checklist that requires parents to check
off words that their child understands as well as uses spontaneously. If the parent identified that their child used a word that was
not on the list, it was added to the checklist. This checklist also
enabled monitoring of the participants’ vocabulary of English
words as well as other languages that all participants were
minimally exposed to in their respective environments.
2.2.3. Speech development
The participants’ articulation skills were monitored using the
Goldman–Fristoe Test of Articulation [62], percentage consonants correct (PCC) as well as a CASALA analysis for consonant
phonological processes. The GFTA-2 measures the number of
phonemes in the English Language the child is able to produce in
comparison with a normative sample. Percentile rankings were
calculated on the GFTA-2 and included for the purpose of giving
a reference to compare each participant’s own progress. The
GFTA-2 is scored on the basis of the child’s performance at
targeted phonemes, with a single scored occurrence of each
targeted phoneme in word initial, medial and final word
positions where these phonemes occur in the English Language.
For example, the phoneme/s/is scored at word initial position in
‘scissors’, word medial position in ‘pencils’ and word final
position in ‘house’. The participants’ pronunciation of the/s/
phoneme is not scored in other occurrences in the speech
sample, such as ‘this’ and ‘glasses’, which were included in the
assessment for other targeted phonemes. In addition to
percentile rankings, a more culturally sensitive percentage
consonant correct (PCC) score was calculated. The PCC scores
measure the percentage accuracy of the child’s phoneme
productions without comparing it with a normative sample,
thereby making each score directly comparable with the child’s
previous scores on the same speech sample. PCC expresses the
percentage of consonant sounds that were articulated correctly
to provide a score of phonetic accuracy [63]. The PCC scores in
this study were attained by comparing phonetic transcriptions of
each participant’s speech productions from the GFTA-2 to that of
a local Singaporean adult model. In order to analyse the
development of participants’ speech error patterns, participants’
responses on the GFTA-2 were also analysed for phonological
processes using the CASALA [64].
2.3. Procedure
This is a phase 1 study with a multiple baselines across
participants design. Participants received 3 speech perception
intervention sessions per week for 6 weeks or until they reached
the ceiling of the intervention programme, whichever happened
first. The baseline data collection period was randomly allocated to
be either one or two weeks in duration (three or six sessions) as it is
a feature of multiple-baseline across subjects experiments to
extend the baseline phase for some participants. The withdrawal
phase at the end of intervention programme took place over one
The schedule of probes administered is illustrated in Fig. 2. The
generalisation and control probes were administered in the
baseline phase of the SPEAK programme and all three probes
were administered in the intervention and withdrawal phases of
the programme. During the baseline and withdrawal phases, probe
data was collected 3 times a week. In the intervention phase, probe
data was collected after therapy sessions 1, 3, 6, 9, 12, 15 and 18.
3. Results
3.1. SPEAK-Intervention
All participants progressed through the SPEAK-Intervention
programme. S1 and S2 advanced from level 3 to the highest level of
the intervention programme at level 10; S1 reached criterion of the
highest level of the intervention programme at the last scheduled
intervention session whilst S2 completed the intervention
programme after the 13th session. S3 started at level 1 and
finished at level 7 at the end of the 18 therapy sessions (see Fig. 3).
The SPEAK-Probes highlighted improvement on untrained
words. The generalisation probes showed that the intervention
impacted positively on untrained words at the same speech
perception level that therapy was received for all participants. In
contrast, the control data showed no generalisation to untrained
words at increased levels of speech perception difficulty that had
not been targeted in therapy (see Fig. 3).
For S1, some of the control probe data were not collected
because SPEAK-Intervention was initially designed with only 10
speech perception levels. S1’s improvement through the intervention programme was more rapid than anticipated resulting in the
need for control probes beyond level 10. Consequently, control
data for S1 were not available from the last probe point in the
therapy phase and throughout the withdrawal phase.
Fig. 2. Schedule of progress probes.
J. Lew et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 1716–1725
Table 2
Speech discrimination results.
Early Speech Perception (ESP) Test
Total score (max = 36)
Category level (max = 4)
SPEAK-Baseline Results
Total score (max = 100)
Skill level (max = 10)
significant growth in receptive vocabulary, whilst the regression
in S3’s vocabulary was not statistically significant.
Using the 2500+ Words, receptive vocabulary growth was
reported by the parents (21%, 161% and 210%, in subjects 1, 2, and
3, respectively). Positive gains were also reported in expressive
vocabulary (18.6% and 215% and 80%, in subjects 1, 2, and 3,
respectively). See Table 3.
3.3. Speech development
Fig. 3. Speech perception probe results.
3.2. Pre and post outcome measures
It was anticipated that T-tests would be carried out to compare
measure change in the pre and post outcome measures. The
residuals were screened for autocorrelation, and moderate to
severe autocorrelation was found. No further statistical analysis
was attempted, thus all data were analysed visually.
3.2.1. Speech perception
Post-intervention, the total speech perception scores for all
participants increased on the low-verbal version of the ESP (see
Table 2). There was a single category level change for S3 while S1
and S2 maintained their category level close to ceiling of the test.
3.2.2. Vocabulary
Percentile ranks on the PPVT-4 increased for S1 and S2, whilst a
slight regression was noted for S3 (see Table 3). The PPVT-4
provides growth scale values (GSV) which determines whether
changes in raw scores over time reach statistical significance. If the
difference in GSV values between tests is greater than 8,
statistically significant change may be deduced (p < 0.1) [60].
The GSV results indicate that S1 and S2 made statistically
All participants showed an improvement in their speech
development. S1’s scores remained within the normal range,
however their percentile rank increased following intervention
(see Table 4). S2’s speech development improved slightly but
remained delayed and S3’s percentile range moved from the
severely delayed range to a mild delay. There was also an increase
in PCC scores for all participants following intervention. Participants made between 20% and 40% improvement in PCC accuracy
(see Table 4).
Results from the CASALA analysis of consonant phonological
processes are presented in Table 5. A phonological process was
deemed clinically relevant if it occurred at least 20% of the time.
This was in accordance with McReynold and Elbert [65], who
considered a phonological process to sufficiently affect a child’s
speech to a degree that warrants remediation if it occurred at least
20% of the time. Phonological processes are mostly typical in a
child’s speech, remediating spontaneously at different ages
depending on the type of process. Some phonological processes
do not occur frequently in typically developing speech and their
frequent occurrence may indicate disordered speech development
[66]. S1’s use of phonological processes did not reach clinical
relevance throughout her participation. S2 had a slight reduction in
the number of phonological processes after intervention. After
intervention, S2 had a reduction in the use of atypical phonological
processes from 3 to 2. While S3 increased the number of
phonological processes affecting her speech from 2 to 3 processes,
these processes were typical for their age. An increase in
phonological processes for S3 is to be expected because there
was an increase in the number of words used overall, from 19 to 53
words attempted in the GFTA-2.
3.4. Reliability
3.4.1. Treatment fidelity
An independent Speech Language Pathologist reviewed 10% of
the therapy sessions to determine whether the intervention
protocol was adhered to. The reviewer marked the Speech
Language Pathologist responses in whether she (i) presented the
target words through audition before its visual representation, (ii)
presented the target words 3 times in a phrase during speech
perception intervention, (iii) took accurate therapy data, (iv)
provided a token when the child was accurate and (v) taught on
error responses and provided the child with a token. The
J. Lew et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 1716–1725
Table 3
Vocabulary results.
Standard score
Percentile rank
Growth scale factor (GSF)
Difference in GSF (significant* if difference >8, p < 0.1)
2500+ words (receptive)
Total words
% Change in total words
2500+ words (expressive)
Total words
% Change in total words
independent audit of 10% of therapy videos indicated that the
therapy protocol had been adhered to 100% of the time.
3.4.2. Transcription reliability
10% of the GFTA-2 samples were randomly reviewed by an
independent Speech Language Pathologist for inter-rater and
intra-rater reliability in phonetic transcription results. Intra-rater
reliability for transcription data was 92.5% and inter-rater
reliability was 83.3%.
4. Discussion
4.1. Summary of findings
This study examined whether speech perception intervention
was effective for preschool children with hearing loss, and whether
intensive intervention for speech perception alone had an impact
on vocabulary and speech development. In order to do this, the
Speech Perception Education and Assessment Kit (SPEAK) was
developed and trialled. A single case, multiple baseline study was
implemented with three participants aged 2:6–3:0 years at the
start of the programme.
The SPEAK-Intervention programme was deemed to be a
promising tool for developing speech perception skills in the three
young children with all participants progressing through the
programme. Results from the ESP as well as the SPEAK-Baseline
and Probes showed that speech perception intervention led to
positive change for all 3 preschool children with hearing loss.
Participants generalised their auditory development to untrained
words at the same level as those trained. Moreover, the participants
maintained their speech perception skills after intervention was
Table 4
GFTA-2 and articulation percentage consonants correct (PCC) results.
Total words attempted
GFTA-2 standard score
GFTA-2 percentile rank
Percentage consonants
correct (PCC)
Change in PCC (%)
withdrawn. The SPEAK-Intervention program is one of the first
speech perception intervention programmes demonstrated to be
promising for use with preschool children with hearing loss.
In addition to progress in speech perception skills, SPEAKIntervention appeared to facilitate vocabulary and speech development. The development of vocabulary and speech as a secondary
impact of speech perception intervention in children with hearing
loss is an important novel finding.
4.2. Speech perception
Speech perception skills of all participants progressed during
the SPEAK-Intervention program as demonstrated when assessed
using the SPEAK-Baseline in both the total score and skill level.
These results indicate that speech perception programmes can be
designed and used efficaciously with preliterate pre-schoolers. The
success of the programme was not only evident throughout the
intervention tasks of the programme, but also in the participants’
ability to generalise their newfound skills to learning unfamiliar or
untrained words. This has positive implications for clinicians, as
they may not need to teach all words in direct therapy, when using
an intensive auditory training programme such as SPEAKIntervention.
The results also highlight that the improved speech perception
skills are maintained once intervention is withdrawn. The
participants’ ability to generalise and maintain speech perception
skills from words used in the intervention programme to
unfamiliar words is a clinically valuable finding. Implementing
programmes that ensure progress is maintained over time
provides clinician and families with confidence that their time
in intervention is utilised efficiently and effectively.
4.3. Vocabulary
In addition to progress in speech perception skills, participants
made progress in their vocabulary development following SPEAKIntervention. This change was measured using the PPVT-4 GSV
scores which examines if change in vocabulary scores is beyond
what would be expected as part of a child’s typical vocabulary
development. According to the PPVT-4, a change in GSV score of
greater than 8 points shows a significant improvement in
vocabulary development beyond the expected from maturity.
J. Lew et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 1716–1725
Table 5
CASALA phonological processes analyses.
Age eliminated
Initial consonant deletion
Alveolar backing
Other backing
Cluster deletion
Final consonant deletion
Stopping fricatives
Cluster reduction
Total processes > 20%
S1 (%)
S2 (%)
S3 (%)
X indicates infrequently used phonological processes in typically developing children.
Two of the 3 participants made statistically significant progress
on the PPVT-4 and all increased their receptive and expressive
vocabulary, as reported by their parents. The two participants who
made significant progress as recorded on the PPVT-4 had reached a
higher level on the SPEAK-Intervention programme than the
remaining participant, supporting the literature that found
correlation between good speech perception skills and vocabulary
development [49]. The post-intervention progress of the participants’ expressive vocabulary development as recorded on 2500+
Words was between 18.6% and 215%, although it could not be
determined whether the reported increases were statistically
There was discrepancy in the degree of vocabulary development recorded on the PPVT-4 with the parent-reported 2500+
words. S1 made the greatest percentile change on the PPVT-4 from
7th to 45th while her parents recorded the lowest number of words
being added to her receptive vocabulary at 21%. S2 showed modest
development on the PPVT-4 from 47th to 63rd percentile while her
parents reported extensive 161% change in her receptive vocabulary. S3 had negative growth on the PPVT-4 from 34th to the 21st
percentile on the PPVT, but her parents reported the most change
(210%) in her receptive vocabulary. Correlation between parent
reports and standardised tests on receptive vocabulary development was examined by Thal [67]. They noted that parent reports
for receptive language did not correlate with standardised tests,
suggesting that parent reports on a child’s receptive language
development need to be supplemented with the collection of
objective data.
Differences in progress as recorded using standardised tools
(such as the PPVT-4) and informal tools are not uncommon.
Standardised tests remove context for the child and therefore
identifying knowledge that the child has consolidated. In addition,
standardised tests often contain culture specific language, which
can affect response to stimuli and standardisation of results. For
example, some words used in the earliest sections of the PPVT-4
such as ‘cookie’, ‘muffin’, ‘mail’, ‘lamp’, and ‘squirrel’ are likely to be
more familiar to children in the norming population. Local children
are likely to use the words ‘biscuit’, ‘cake’, ‘letters’, ‘light’, in place of
the first 4 words while squirrels are uncommonly seen in
Singapore. Informal tools such parent report provide valuable
information regarding the child’s skills and knowledge in context
and therefore may provide a more accurate representation of the
children’s vocabulary development in everyday situations, in
particular expressive vocabulary. Parent-reported vocabulary has
been found to have strong correlation with standardised tests
where studies have been done on families local to the places where
the standardised tests were constructed [68,69]. In the absence of
locally standardised vocabulary tests, emphasis should therefore
be placed on parent-reported measures of vocabulary.
It appears that with improved speech perception skills, children
with hearing loss can learn words without actively being taught
them. This finding has implications for the efficient development of
vocabulary in preschool children born with hearing loss who,
according to Walker and McGregor [54], continue to experience
delay in word learning skills in comparison to their normal hearing
peers in spite of early auditory intervention.
4.4. Speech development
The speech of all children who were recruited in the study also
improved over the short period of SPEAK-Intervention. Progress
was made in speech development on the GFTA-2 for 2 of the 3
participants, and on PCC scores for all participants. However, it is
unknown as to whether this progress was a result of typical speech
development or statistically significant growth.
Phonological process development demonstrated by the
participants was, for the most part, within the normal range for
their age. One participant did not demonstrate progress on the
GFTA-3, even though she demonstrated the most improvement on
the PCC scores in addition to a reduction in the use of atypical
phonological processes.
The fact that speech developed over the period of the
intervention when speech skills were not actively being taught,
is positive in itself. This outcome supports the literature
demonstrating that speech perception skills facilitate speech skills
in children with hearing loss, and that without good speech
perception a child’s speech will be affected.
Although there are comparative studies examining the relationship between speech perception skills and speech development [70,71], this is one of the first studies to demonstrate on the
impact of auditory intervention using a defined auditory hierarchy,
on speech development. This prospective intervention study using
speech perception tests scored independent of children’s speech
output is therefore an important contribution to the understanding
of the impact of speech perception development on speech
4.5. Clinical implications
The SPEAK-Intervention programme was shown to be effective
in developing the speech perception skills of three young
preschoolers with hearing loss. Using a predefined set of words
in the SPEAK-Intervention programme, the participants not only
progressed through the auditory levels, but also generalised these
skills to novel words. The ability to generalise speech perception
skills learnt to processing unfamiliar words is crucial for children
to process and learn from the language in their environment.
Therefore SPEAK-Intervention programme may be a useful clinical
J. Lew et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 1716–1725
tool that can be used to focus a child’s auditory training in an
intensive manner for short periods of time during early intervention.
It appears that additional benefits of the SPEAK-Intervention
programme may include the concomitant development of
vocabulary and speech skills, despite these skills not being directly
trained. The development of auditory skills to establish speech and
language development is the cornerstone of AVT. This is one of the
first studies providing preliminary support to the AVT method of
developing speech and language skills through listening and an
auditory hierarchy. By teaching the children to listen using this
method, language can be overheard and learnt without direct
teaching of every aspect of speech and language over time [72].
However, it appears that the children need to be at a particular
level of the auditory hierarchy for this to occur. Further research is
warranted to explore this relationship further.
Both S1 and S2 reached criterion at level 10 of the intervention
programme and S3 reached level 7 by the end of the study. While
all improved their speech skills following SPEAK-Intervention, only
the two participants with the higher level of speech perception
development had clinically significant improvements on the PPVT4. Therefore, it may be hypothesised that a particular speech
perception skill-level threshold is necessary for children to
effectively listen to and learn words from their daily activities;
and that a lower level of speech perception skill is enough for
speech skills to progress without direct speech training.
This is one of the first Intervention studies that aims to
investigate the efficacy of a specific component of auditory-verbal
therapy, and the single-case multiple baseline design has been
found to be important for the purposes of further study on the
efficacy of components of and techniques used in AVT. Singlesubject study designs are prevalent in the communication sciences
literature [73]. Its flexibility enables the researcher to tailor an
intervention in accordance to the individualised needs of the
participants involved in the study, yielding results that have ready
application to clinical practice in addition to providing empirical
evidence in support for therapeutic interventions [73]. Given the
lack of evidence in documenting the therapeutic process of
auditory-verbal practice [30], it is recommended that singlesubject studies be adopted within clinical practice for more
widespread efficacy studies of therapeutic strategies used in
auditory-verbal practice.
perception skills in young children with hearing loss should not
completely replace functional speech and language intervention.
Speech and language skills are learnt through play and social
interaction, and should not be forgotten. It is hoped through further
studies using the SPEAK-Intervention programme, the authors can
find the ideal mix between functional therapy and intensive speech
perception intervention to produce the most effective and efficient
early intervention programme for optimal speech and oral language
development for children with hearing loss.
5. Conclusions
This is one of the first intervention studies to respond to the call
of Moeller et al. [7] to determine whether focussed listening
practice can impact on speech development. The results of this
Phase 1 study shows promise regarding training speech perception
and the impact on speech development. However, further research
with a larger number of children and in particular the inclusion of
control children is necessary. More specifically, the study
examined the efficacy a newly developed speech perception
training programme (SPEAK-Intervention), and the impact of
training speech perception on the vocabulary and speech
development of young preschool aged children with hearing loss.
Our findings provide preliminary support for the effective
provision of auditory intervention to preschool children with
permanent hearing loss. Results showed that speech perception
training is possible with young children and that this training has
some additional benefits for vocabulary and speech development.
This in-turn makes this intervention study one of the first to
demonstrate the premise of AVT; supporting the development
speech and language through listening. However, findings should
be viewed with caution as the study needs to be replicated on a
larger cohort. In addition, some research into optimal practice
schedules using the SPEAK-Intervention programme and where it
fits in the typical early intervention process are required.
The authors wish to thank colleagues at the ENT Clinic, National
University Hospital, as well as the families who participated in
this study.
4.6. Limitations
The findings from the study are exciting however there are
several limitations to this study. The participant numbers was
small and therefore outcomes cannot be directly generalised to the
population of young hearing impaired children. Further controlled
studies with a larger cohort are required.
The authors were unable to run statistics on the data due to
issues with autocorrelation. This will need to be considered in the
development of future methodologies, as determining whether
progress in post-intervention outcomes is significant or otherwise
is required.
The lack of normative vocabulary and speech development data
on Singaporean pre-school-aged children affected the extent to
which data collected may be compared to children with normal
hearing in Singapore. It was also difficult to accurately ascertain
the level of vocabulary or speech perception development for the
children recruited in this study. Future Phase-2 studies using
SPEAK-Intervention should include a control group to allow the
influence of developmental growth to be measured more
Finally, the results should be viewed with caution. While the
SPEAK-Intervention programme has promise, drilling speech
[1] Australian Hearing, Demographic Details and Aetiology of Persons Under the Age
of 17 Years With a Hearing Impairment Who Have Been Fitted With a Hearing Aid,
National Acoustic Laboratories, Chatswood, 2005.
[2] H.M. Fortnum, A.Q. Summerfield, D.H. Marshall, A.C. Davis, J.M. Bamford, Prevalence of permanent childhood hearing impairment in the United Kingdom and
implications for universal neonatal hearing screening: questionnaire-based ascertainment study, Br. Med. J. 323 (2001) 536–540.
[3] A.L. Mehl, V. Thomson, Newborn hearing screening: the great omission, Pediatrics
101 (1) (1998) e4.
[4] National Center for Hearing Assessment and Management, Prevalence of Congenital Hearing Loss, NCHAM, 2010 Available from: http://www.infanthearing.org/summary/prevalence.html (accessed 07.03.13).
[5] M.P. Moeller, E. McCleary, C. Putman, A. Tyler-Krings, B. Hoover, P. Stelmachowicz,
Longitudinal development of phonology and morphology in children with lateidentified mild–moderate sensorineural hearing loss, Ear Hear. 31 (5) (2010)
[6] M.P. Moeller, J.B. Tomblin, C. Yoshinaga-Itano, C.C. McDonald, S. Jerger, Current
state of knowledge: language and literacy of children with hearing impairment,
Ear Hear. 28 (2007) 740–753.
[7] M.P. Moeller, B. Hoover, C. Putman, K. Arbataitis, G. Bohnenkamp, B. Peterson,
et al., Vocalizations of infants with hearing loss compared with infants with
normal hearing: Part I. Phonetic development, Ear Hear. 28 (5) (2007) 605–627.
[8] J. Lukomski, Deaf college students’ perceptions of their social–emotional adjustments, J. Deaf Stud. Deaf Educ. 12 (4) (2007) 486–494.
[9] M.P. Moeller, Current state of knowledge: psychosocial development in children
with hearing impairment, Ear Hear. 28 (6) (2007) 729–739.
J. Lew et al. / International Journal of Pediatric Otorhinolaryngology 78 (2014) 1716–1725
[10] P. Theo van Eldik, J.W.V. Treffers, F.C. Verhulst, Mental health problems of deaf
Dutch children as indicated by parents’ responses to the child behavior checklist,
Am. Ann. Deaf 148 (5) (2004) 390–395.
[11] L. Robertson, Literacy Learning for Children Who Are Deaf of Hard of Hearing, A.G.
Bell Association for the Deaf and Hard of Hearing, Washington, 2000.
[12] A.E. Geers, H. Hayes, Reading, writing, and phonological processing skills of
adolescents with 10 or more years of cochlear implant experience, Ear Hear.
32 (1) (2010) 49S–59S.
[13] F. Venail, A. Vieu, F. Artieres, M. Mondain, A. Uziel, Educational and employment
achievements in prelingually deaf children who receive cochlear implants, Arch.
Otolaryngol. Head Neck Surg. 136 (4) (2010) 366–372.
[14] Cooperative Research Centre for Cochlear Implant and Hearing Aid Innovation
(CRC HEAR), Listen Hear: The Economic Impact and Cost of Hearing Loss in
Australia Access Economics, VicDeaf, Victoria, 2006.
[15] D. Jung, N. Bhattacharyya, Association of hearing loss with decreased employment and income among adults in the United States, Ann. Otol. Rhinol. Laryngol.
121 (12) (2012) 771–775.
[16] P.E. Mohr, J.J. Feldman, J.L. Dunbar, A. McConkey-Robbins, J.K. Niparko, R.K.
Rittenhouse, et al., The societal costs of severe to profound hearing loss in the
United States, Int. J. Technol. Assess. Health Care 16 (4) (2000) 1120–1135.
[17] E. Cole, C. Flexer, Children with Hearing Loss: Developing Listening and Talking
(Birth to Six), Plural Publishing, San Diego, 2008.
[18] D. Querleu, X. Renard, F. Versyp, L. Paris-Delrue, G. Crepin, Fetal hearing, Eur. J.
Obstet. Gynecol. Reprod. Biol. 29 (1988) 191–212.
[19] A. Vouloumanos, J.F. Werker, Listening to language at birth: evidence for a bias for
speech in neonates, Dev. Sci. 10 (2) (2007) 159–171.
[20] F. Ramus, M.D. Hauser, C. Miller, D. Morris, J. Mehler, Language discrimination by
human newborns and by cotton-top tamarin monkeys, Science 288 (5464) (2000)
[21] R.J. Ruben, R. Schwartz, Necessity versus sufficiency: the role of input in language
acquisition, Int. J. Pediatr. Otorhinolaryngol. 47 (2) (1999) 119–226.
[22] J. Mehler, P. Jusczyk, G. Lambertz, N. Halsted, J. Bertoncini, C. Amiel-Tison, A
precursor of language acquisition in young infants, Cognition 29 (2) (1988)
[23] D.L. Molfese, V.J. Molfese, Hemisphere and stimulus differences as reflected in the
cortical responses of newborn infants to speech stimuli, Dev. Psychol. 15 (6)
(1979) 505–511.
[24] P.G. Simos, D.L. Molfese, Electrophysiological responses from a temporal order
continuum in the newborn infant, Neuropsychologia 35 (1) (1997) 89–98.
[25] A. Sharma, A.A. Nash, M. Dorman, Cortical development, plasticity and reorganisation in children with cochlear implants, J. Commun. Disord. 42 (2009)
[26] Joint Committee on Infant Hearing, Year 2000 position statement: principles and
guidelines for early hearing detection and intervention programs, Pediatrics 106
(2000) 798–817.
[27] Joint Committee on Infant Hearing, Year 2007 position statement: principles and
guidelines for early hearing detection and intervention programs, Pediatrics 120
(4) (2007) 898–921.
[28] Centers for Disease Control and Prevention, National Center for Health Statistics,
Healthy People 2010: Final Review, 2011.
[29] S. Schwartz, Choices in Deafness: A Parents’ Guide to Communication Options,
[30] E.A. Rhoades, Research outcomes of auditory-verbal intervention: is the approach
justified? Deaf. Educ. Int. 8 (3) (2006) 125–143.
[31] A.G. Bell Academy for Listening and Spoken Language, Principles of AuditoryVerbal Therapy, 2007 Available from: http://listeningandspokenlanguage.org/
AcademyDocument.aspx?id=563 (accessed 18.01.13).
[32] W. Estabrooks, Auditory-Verbal Therapy and Practice, Alexander Graham Bell
Association for the Deaf and the Hard of Hearing Inc., USA, 2006.
[33] D. Dornan, L. Hickson, B. Murdoch, T. Houston, G. Constantinescu, Is auditoryverbal therapy effective for children with hearing loss? Volta Rev. 110 (3) (2010)
[34] E.A. Rhoades, T.H. Chisolm, Global language progress with an auditory-verbal
approach for children who are deaf or hard of hearing, Volta Rev. 102 (1) (2000)
[35] A. Fulcher, A.A. Purcell, E. Baker, N. Munro, Listen up: children with early
identified hearing loss achieve age-appropriate speech/language outcomes by
3 years-of-age, Int. J. Pediatr. Otorhinolaryngol. 76 (12) (2012) 1785–1794.
[36] D. Dornan, L. Hickson, B. Murdoch, T. Houston, Outcomes of an auditory-verbal
program for children with hearing loss: a comparative study with a matched
group of children with normal hearing, Volta Rev. 107 (1) (2006) 37–54.
[37] J. Tuohy, J. Brown, C. Mercer-Moseley, L. Walsh, St. Gabriel’s Curriculum, second
ed., St Gabriel’s School for Hearing Impaired Children, Sydney, 2005.
[38] Cochlear, Listen Learn and Talk, SOS Printing Group, Australia, 2003.
[39] Q.-J. Fu, J. Galvin, X. Wang, G. Nogaki, Moderate auditory training can improve
speech performance of adult cochlear implant patients, Acoust. Res. Lett. Online 6
(3) (2005) 106–111.
[40] G.C. Stecker, G.A. Bowman, E.W. Yund, T.J. Herron, C.M. Roup, D.L. Woods,
Perceptual training improves syllable identification in new and experienced
hearing aid users, J. Rehabil. Res. Dev. 43 (4) (2006) 537–552.
[41] R. Sweetow, J.H. Sabes, The need for and development of an adaptive Listening and
Communication Enhancement (LACE) program, J. Am. Acad. Audiol. 17 (2006)
[42] J.-L. Wu, H.-M. Yang, Y.-H. Lin, Q.-J. Fu, Effects of computer-assisted speech
training on Mandarin-speaking hearing-impaired children, Audiol. Neurotol.
12 (2007) 307–312.
[43] D. Swingley, The roots of the early vocabulary in infants’ learning from speech,
Curr. Dir. Psychol. Sci. 17 (5) (2008) 308–312.
[44] J.F. Werker, C.T. Fennell, Infant speech perception and language acquisition:
methodological underpinnings, in: J. Colombo, P. McCardle (Eds.), Infant Pathways to Language: Methods, Models, and Research Directions, Taylor & Francis
Group, New York, 2009, pp. 85–98.
[45] J.F. Werker, H.H. Yeung, Infant speech perception bootstraps word learning,
Trends Cogn. Sci. 9 (11) (2005) 519–527.
[46] P. Kuhl, Linking infant speech perception to language acquisition, in: P. McCardle,
J. Colombo, L. Freund (Eds.), Infant Pathways to Language: Methods, Models and
Research Directions, Taylor & Francis Group, New York, 2009, pp. 213–244.
[47] D.L. Molfese, Predicting dyslexia at 8 years of age using neonatal brain responses,
Brain Lang. 72 (2000) 238–245.
[48] D.L. Molfese, V.J. Molfese, Discrimination of language skills at five years of age
using event related potential recorded at birth, Dev. Neuropsychol. 24 (1997)
[49] J.L. Desjardin, S.E. Ambrose, A.S. Martinez, L.S. Eisenberg, Relationships between
speech perception abilities and spoken language skills in young children with
hearing loss, Int. J. Audiol. 48 (2009) 248–259.
[50] L.E. Paatsch, P.J. Blamey, J.Z. Sarant, C.P. Bow, The effects of speech production and
vocabulary training on different components of spoken language performance, J.
Deaf Stud. Deaf Educ. 11 (1) (2006) 39–55.
[51] D.L. Mills, C. Prat, R. Zangl, C.L. Stager, H.J. Neville, J.F. Werker, Language experience and the organisation of brain activity to phonetically similar words: ERP
evidence from 14- to 20-month-old, J. Cogn. Neurosci. 16 (2004) 1452–1464.
[52] C.L. Stager, J.F. Werker, Infants listen for more phonetic detail in speech perception than in word-learning tasks, Nature 388 (1997) 381–382.
[53] J.F. Werker, C.T. Fennell, K.M. Corcoran, C.L. Stager, Infants’ ability to learn
phonemically similar words: effects of age and vocabulary size, Infancy 3 (1)
(2002) 1–30.
[54] E.A. Walker, K.K. McGregor, Word learning processes in children with cochlear
implants, J. Speech Lang. Hear. Res. 56 (2) (2013) 375–387.
[55] A.R. Lederberg, P.E. Spencer, Word-learning abilities in deaf and hard-of-hearing
preschoolers: effect of lexicon size and language modality, J. Deaf Stud. Deaf Educ.
14 (1) (2009) 44–62.
[56] B. Dodd, B. McIntosh, Two-year-old phonology: impact of input, motor and
cognitive abilities on development, J. Child Lang. 37 (5) (2010) 1027–1046.
[57] L.S. Eisenberg, Current state of knowledge: speech recognition and production in
children with hearing impairment, Ear Hear. 28 (6) (2007) 766–772.
[58] A. Boothroyd, Speech perception and sensorineural hearing loss, in: M. Ross, T.G.
Giolas (Eds.), Auditory Management of Hearing-Impaired Children, University
Park Press, Baltimore, 1978, pp. 117–144.
[59] J.S. Moog, A.E. Geers, Early Speech Perception (ESP) Test, Central Institute for the
Deaf, St. Louis, 1990.
[60] L.M. Dunn, D.M. Dunn, Peabody Picture Vocabulary Test (PPVT-4), fourth ed.,
Pearson, Texas, 2007.
[61] S. Armstrong, 2500+ Words List, St. Gabriele’s Early Intervention Centre,
Brisbane, 1992.
[62] R. Goldman, M. Fristoe, Goldman Fristoe Test of Articulation (GFTA), second ed.,
American Guidance Service, USA, 2000.
[63] L.D. Shriberg, D. Austin, The Percentage of Consonants Correct (PCC) metric:
extensions and reliability data, J. Speech Lang. Hear. Res. 40 (4) (1997) 708–722.
[64] H.E.A. Rworks, Computer Aided Speech and Language Assessment (CASALA),
HEARworks, Australia, 2007.
[65] L.V. McReynolds, M. Elbert, Criteria for phonological process analysis, J. Speech
Lang. Hear. Res. 46 (2) (1981) 197–204.
[66] J.E. Roberts, M. Burchinal, M.M. Footo, Phonological processes decline from 2.5 to
8 years, J. Commun. Disord. 23 (3) (1990) 205–217.
[67] D.J. Thal, L. O’Hanlon, M. Clemmons, L. Fralin, Validity of a parent report measure
of vocabulary and syntax for preschool children with language impairment, J.
Speech Lang. Hear. Res. 42 (2) (1999) 482–496.
[68] A.K. Prezbindowski, A.R. Lederberg, Vocabulary assessment of deaf and heard-ofhearing children from infancy through the preschool years, J. Deaf Stud. Deaf
Educ. 8 (4) (2003) 383–400.
[69] D. Thal, J.L. Desjardin, L.S. Eisenberg, Validity of the MacArthur–Bates Communicative Development Inventories for measuring language abilities in children with
cochlear implants, Am. J. Speech Lang. Pathol. 16 (2007) 54–64.
[70] P.J. Blamey, J.Z. Sarant, L.E. Paatsch, J.G. Barry, C.P. Bow, R.J. Wales, et al., Relationships among speech perception, production, language, hearing loss and age in
children with impaired hearing, J. Speech Lang. Hear. Res. 44 (2) (2001) 264–285.
[71] L.E. Paatsch, P.J. Blamey, J.Z. Sarant, L.F.A. Martin, C.P. Bow, Separating contributions of hearing, lexical knowledge, and speech production to speech-perception
scores in children with hearing impairments, J. Speech Lang. Hear. Res. 47 (4)
(2004) 738–750.
[72] N. Akhtar, J. Jipson, M.A. Callanan, Learning words through overhearing, Child
Dev. 72 (2) (2001) 416–430.
[73] R.L. Tate, S. Mcdonald, M. Perdices, L. Togher, R. Schultz, S. Savage, Rating the
methodological quality of single-subject designs and n-of-1 trials: introducing
the Single-Case Experimental Design (SCED) scale, Neuropsychol. Rehabil. 18 (4)
(2008) 385–401.