MSc Speech and Hearing Sciences - Dissertation Abstracts
This page contains abstracts of some of the student project dissertations undertaken as part of the MSc in Speech and Hearing Sciences.
Beat Detection and Specific
Language Impairment: How is Sensitivity to Amplitude Envelope Onsets related to
Speech, Language and Literacy?
Chloë Bate (2003)
This study looked at “beat
detection” (sensitivity to changes in amplitude envelope onsets) in a group of
12 children with language impairment (LI) and 11 control children matched on
age and non-verbal IQ. This auditory processing ability is argued to be a
non-speech-specific mechanism for separating onsets and rimes and therefore, an
important factor in the development of phonological awareness. A deficit in
this ability has been postulated as the primary deficit in development dyslexia
and it was argued that a serious deficit could lead to spoken as well as
written impairments of the kind ground in specific language impairment. Thus,
the speech, language and literacy abilities of the children participating were
assessed to investigate a possible relationship between these and beat
detection ability. Results showed that a significant proportion, though not
all, of the LI children exhibited the deficit and these were the ones that
generally had the most problems with literacy and phonological awareness. Although
the beat detection deficit did not seem to be a sufficient cause of the speech
and language problems seen in theses children, there did seem to be a close
relationship between beat detection ability and phonological awareness and
literary skills. This suggests that a beat detection deficit may be a
contributing or aggravating factor to the phonological awareness and, thereby,
literacy problems seen in many of the children with LI in this study.
Can Normal Listeners Adapt to an
Upward Asymmetric Spectral Shift? Implications for Bilateral Cochlear Implants
Lucinda Saul (2003)
Bilateral cochlear implants may
lead to binaural advantages that enhance speech perception and localisation
difficulties. However, in bilateral cochlear implant users electrode array
insertion lengths are likely to differ between the two implants, such that they
must overcome limitations imposed by the difference in frequency-to-place
mismatch to obtain these advantages. The spectral shift experienced in each ear
will differ, generating an asymmetric shift between the two ears. Adaptation to
these spectral shifts has been demonstrated in simulation studies, but
adaptation to a dichotic spectral shift across the two ears has yet to be
investigated. In this study, the effects of an upward asymmetric shift, with
the equivalent of a 6mm basalward shift on the basilar membrane in one ear, has
been stimulated and performance tested under binaural and
monaural conditions. A sine wave vocoder simulated bilateral cochlear implants
with a total of six frequency channels. There was a dichotic presentation of
the frequency information to the two ears from the six input analysis bands, so
that the three odd frequency sine waves generated were assigned to one ear and
the even frequency sine waves were assigned to the contra-lateral ear. Thus,
subjects would benefit from integrating information across the two ears and
would not attend to one ear alone. After nine 40-minute sessions of connected
discourse tracking with the dichotic shifted condition, speech perception
performance improved significantly in the trained dichotic shifted, monotic
odd-channels shifted and unshifted conditions. However, listeners were unable
to optimise their speech perception by binaural integration. In post-training
sentence perception tests, there was no significant difference between the
dichotic shifted condition and the monotic even-channels unshifted condition,
suggesting that listeners were only attending to their better ear. Although
normal listeners were unable to effectively integrate the binaural information,
it is clear that they were able to adapt to the trained condition to some
extent, but it is unclear exactly what they were learning from it. It is
possible that listeners require longer exposure to the asymmetric spectral
shift to adapt and to achieve binaural integration.
The Resolution of Lexical
Ambiguity arising from Place Assimilation: Evidence from a Gated Speech Task
Sarah Bateman (2002)
Place assimilation in English can
give rise to lexical ambiguity, as in the sentence “There’s your ca[p] by
the door”, where ca[p] could be interpreted either as ‘cap’ or an
assimilated form of ‘cat’. The experiment reported here used a gating task to
investigate the timing and effectiveness of different cues used by listeners to
resolve this type of ambiguity. It was found that in a neutral sentence
context, listeners were more likely to identify the ambiguous word as a word
directly matching the surface form (non-coronal), although some identified it as
a word in assimilated form (coronal). A constraining interpretive context
favouring the coronal word increase the proportion of coronal word candidates,
although it did not reduce the time needed to identify ambiguous words with
confidence. When acoustic information about an ambiguous word was most salient
– at word offset and before the
subsequent word was fully identified – there was a strong perceptual preference
for the word most directly matching the surface form. Contrary to a prediction
that a phonological context legitimising assimilation should allow for more
coronal candidates, such a context appeared instead to strengthen the acoustic
information about the non-coronal place of articulation, thereby increasing the
proportion of non-coronal candidates. This effect was shown even when a
preceding interpretive context made the non-coronal candidate highly
implausible. The number of coronal candidates increased only when further
lexical information became available. These findings are discussed in the light
of predictions derived from psycholinguistic and engineering models of spoken
word recognition.
The Importance of Pitch
Information in Speech Recognition with reference to Mandarin Chinese
Yun-Chin Chou (2002)
The aim of this study is to investigate
the contribution of pitch information to the performance of Mandarin speech
recognisers. In this project, a telephone speech database was used to build the
recogniser. Different forms of pitch-based features: Fx, delta Fx, delta delta
Fx, normalised Fx, and their different combinations were incorporated into the
feature vectors in a series of experiments observing their effects on the
Mandarin recogniser. The results show that delta Fx has the largest enhancement
to the recognition rate, compared to other pitch-based features, while Fx as
sole pitch feature causes performance degradation. Normalising Fx and
clustering the data files of the same gender are helpful. The experiment result
from trigram suggests that there is no obvious interaction between the language
model and Fx features.
The Effect of Timbre on Pitch
Perception in Pianists, Violinists and Non-Musicians
Rebecca Dumican (2002)
The auditory abilities of musicians compared to those of
non-musicians have long been of great interest and have sparked a large amount
of research in hearing science, psychology and other related fields. The focus
of this research has often been on the ability of musicians to outperform
non-musicians in frequency discrimination tasks and the effect of timbre on
pitch perception in all populations. How musicians have become better at
frequency discrimination tasks is an important issue and researchers have
suggested various explanations. Musicians may have an improved overall auditory
capability, or their skill may lie in being able to ignore the interference of
ambiguous characteristics of a tone such as timbre. Timbre is reported to have
a deleterious effect on pitch perception in both musicians and non-musicians.
There is some evidence to suggest that “bright” or “dull” timbres can produce a
bias in the pitch percept. Some research into the skill of musicians has found
that there may be an effect of musical discipline on the ability to perform
fine frequency discrimination tasks. For example, the experience of tuning a
musical instrument regularly may enhance this ability. To this end, three
subject groups: non-musicians; violinists and pianists were compared for the
thresholds they obtained in a set of frequency discrimination tasks. The effect
of timbre upon these frequency discrimination thresholds was assessed using
some tones of markedly different timbre. It was found that the pianists and the
violinists produced almost identical thresholds and that both groups of
musicians outperformed the non-musicians in the set of frequency discrimination
tasks. All subject groups found timbre to be a factor which interfered with
frequency discrimination. However, the musicians found timbre differences less
distracting than non-musicians. This shows that musicians cannot ignore timbre,
but that they may utilise the similarity between two tones in order to produce
an accurate pitch estimate. Tones with a particularly “bright” or “dull” timbre
did produce a bias in the pitch percept, subjects hearing them as higher or lower
in pitch respectively. In this experiment, experience of tuning [a musical
instrument] had little effect on frequency discrimination thresholds,
suggesting that musical experience alone accounts for the enhanced ability, not the specific training of a musical discipline.
Single-Word Processing by
Japanese-English Bilinguals: A 3T fMRI Study
Ryoko Matsumoto (2002)
Neural representation of two
different types of orthography: Japanese kanji and the English alphabet
was investigated using fMRI. The subjects were Japanese-English late bilinguals and were shown two-character kanji words and their
translation in English in single word and text conditions. As previous kanji
reading studies have shown contrasting activation data, probably because of
inconsistent criteria in the choice of stimuli, we used only concrete nouns for
both Japanese and English stimuli. The
results revealed that reading Japanese words activated the left interior insula
and the right precuneus, indicating that the subjects used subvocal
articulation and recognised the words more as images. When reading
English words, the left fusiform gyrus and bilateral cingulate gyri were
activated, which suggests that the subjects tried to decode the sequence of
letters and load them from memory. Presenting multiple words in text conditions
revealed that horizontally-presented texts induced smoother eye movements.
Significant activation was also observed in the cerebellum,
indicating that it serves for non-motor linguistic functions as well.
The Plasticity of the Brain
regarding Auditory Perception – A Project Using Spectrally-Rotated Speech
Ruth Finn (2001)
There is much evidence to suggest
that listeners can learn to perceive speech that is so distorted as to be
unintelligible initially. During the course of this study, four subjects
underwent a training programme following the Continuous Discourse Tracking
(CDT) method, using spectrally-rotated speech (an extreme distortion, initially
studied by Blesser (1969)). Each subject completed six hours of this training
(eight 45-minute sessions) and a series of speech perception tests. Results
from these subjects were compared with results from four controls who only
carried out the perception tests. It was shown that only subjects trained to
perceive spectrally-rotated speech had an increased ability to do so. In
sentence tests with a female speaker and only audio information, performance by
the trained group increased 5% mean words correct (after no training) to 27
mean words correct (after 3 hours of CDT) and finally to 42 mean words correct
(after 6 hours of CDT). Similar results were found from tests using a male
speaker and audio information alone: 9 mean words correct initially, increasing
to 18% after 3 hours of CDT, and 26% correct after 6 hours of CDT. The
performance of the trained group also showed significant improvement in
audio-visual sentence tests: 34% mean words correct initially; 74% correct
after 3 hours of CDT and 83% correct after 6 hours of CDT. Although it is
unknown whether a complete adaptation to the spectrally-rotated speech is
possible, it is clear that significant progress can be made over a relatively
short period of time.
The Evolutionary Nature of
Emotion: Vocal Cues to Happiness
Victoria Maschio (2001)
The aim of this study is to
investigate the nature of five positive emotions which are distinguishable by
voice and not facial expression. These are Amusement, Achievement, Relief,
Contentment and Sensual Pleasure. The two theories tested are the evolutionary
perspective of “basic” emotions proposed by Ekman and Russell’s theory of
emotional space. The stimuli used were non-verbal expressions of emotion of
short duration. The study is divided into three parts: a
categorisation test investigating Ekman’s hypothesis; a multidimensional
scaling test to try and create a similar model to Russell’s and lastly an
observational acoustic analysis of the five better-recognised stimuli. The
results showed that recognition of the emotions was well above chance level and
that Amusement, Achievement, Relief and a form of Pleasure are indeed basic
emotions. It was also revealed that these
emotions are not related to Russell’s model of emotional space. The acoustic
analysis showed that features such as voice quality and
fundamental frequency trace can differentiate these emotions, even though the
evidence obtained was not conclusive.
An Acoustic, Larynographic and
Perceptual Study of Opera and Belt Singing Voice Qualities
Esther Shanson (2001)
This study examined the
perceptual, acoustic and laryngographic differences between opera and belt
voice qualities, as defined by the physiological specifications of the Estill
model. The voice qualities were recorded on three pitches and four vowels by
Estill-trained sopranos. The perceptual tests on these recordings were played
to twenty naïve and twenty expert subjects. The
perceptual difference between opera and belt was found to be significant. The
voice qualities were more reliably distinguished by the expert subjects.
Differences between the voice qualities were less obvious at higher pitches and
on certain vowels. Front and open vowels on A4 were most suited to belt
quality. The closed quotient values were considerably higher for belt, rather
than opera quality. Higher spectral harmonics were enhanced in belt, whereas
the fundamental frequency had a particularly high intensity in opera quality.
In both qualities, there was evidence for the singer’s formant. Examining the
same data on acoustic, larynographic and perceptual levels gave a more complete
insight into these voice qualities.
Text-to-Speech (TTS) Synthesis
Evaluation: A Study on the Reliability of the ITU-T Standard Recommendation
P.85 for the Evaluation of English Synthesisers on the Web
Yolanda Vasquez-Alvarez (2001)
An evaluation was conducted on
six TTS systems for English in order to study the reliability of the ITU-T
Standard recommendation P.85. This recommendation is based on subjective
judgements on a number of rating scales for individual TTS systems. This
recommendation was compared with a much simpler method, i.e. a Pair Comparison
(PC) test, based on pair comparison preferences. Four different genre materials
were used in both tests, i.e. E-mail, news, catalogue entries and
name-address-phone numbers which were considered representative of the kind of
texts which technological applications will have to deal with. The final aim of
this study was to compare the validity of both methods. It was found that the
results of both tests were consistent and few differences were observed.
Therefore, it was concluded that the ITU-T appears to be as reliable a method
as the PC test in terms of retest reliability. However, it presents many
problems with the scales and the interpretation of results when using Mean
Opinion Scores (MOS). It is also less easy to run because participants are
exposed to much more information which they need to retain when making their
judgements. It must, however, be remembered that there are some constraints to a project run on
such a small scale. Therefore, future work should be carried out in order
to confirm, extend or reject the
findings presented in this study.
A Computer-Based Auditory
Training of English Contrasts for Cantonese Speakers
Elizabeth W.W. Chua (2000)
Many studies have shown that
perceptual training with appropriately selected prototype stimuli would enhance
L2 learners’ ability to identify new non-native speech sounds. Using the CSLU
Toolkit, this project attempts to design a computer-based auditory training
module that helps Cantonese speakers to identify some difficult English voicing
contrasts more accurately. Our training procedure has followed Jamieson’s
guidelines (1995) and employed the perceptual fading technique to redirect
listeners’ attention to the critical duration cues of fricative voicing
contrasts. This method has proved to be efficient in improving listeners’
identification accuracy. After a one-week period of training, the subjects have
shown significant improvements in perception, from pre-test to post-test. However, training did not seem to transfer
from the trained to the untrained positions. Moreover, only a small generalisation
effect was found in our results. The limited success in the transfer of
training is mainly due to the inadequate variety of training stimuli and number
of speakers in our module. These findings reassert the
important roles of stimulus variability and talker variability in designing an
effective auditory training programme. In terms of the subjects’ evaluation of
this training module, they regard it as being very useful in helping them to
learn the different contrasts. Most feel more confident in identifying the
non-native speech sounds after completing the training. On the whole, this
study has demonstrated the viability of using an auditory training in L2
pedagogy.
Speech Synthesis by Word
Concatenation: An Investigation into the Relative Importance of Intonation,
Duration and Speech Segment Recording Conditions on the Preferences of
Listeners
Mary Jane Paly Vera (2000)
This work is concerned with
speech synthesis by the concatenation of speech segments and more specifically,
about how the process of unit selection in concatenative synthesis systems
could be improved. Unit selection is very important for the production of
better quality synthetic speech. By choosing better speech segments from a
speech database, concatenative speech synthesis systems can minimise signal processing
such as smoothing and prosody manipulation of concatenate speech segments and,
therefore, they can introduce less distortion in the final synthesis.
In
this study, the relative importance of intonation, duration and speech segment
recording conditions on listeners’ preferences was investigated. However, these
were just some of the factors considered during the unit selection process. An
experiment was designed in which the relative importance of these factors was
tested against the perception of telephone users. Telephone users were the
subjects of this study. since synthetic speech produced by concatenative
systems is mainly used in over-the-telephone applications. For this reason,
this area demanded further investigation. In addition, we chose to work with
words as the speech segment for our speech synthesis. After creating several
synthetic utterances, a perceptual test was run. The results obtained were used
to create a rank ordering for the three different factors that we were
investigating. The results of the experiment showed that intonation was the
factor that had the greatest influence on the listeners.
A Spreading Activation Model of
Word Selection
Maria Ovens (1999)
A three-layer spreading activation model of word selection
was developed within the framework established by Dell’s 1988 connectionist
model of speech production. The model uses either semantic or phonological
information, or a combination of the two, to select a word for production. A
proposed mechanism for word priming, residual activation in the phonological
and semantic layers, was investigated. Experiments were carried out which
demonstrate that the model is capable of reproducing facilitation and inhibition
effects found in human subjects, but only at the expense of setting a large
number of arbitrary parameters. In addition, further work is suggested, which
might go some way towards alleviating this problem, and which might allow the
model to be used for stimulating other psycholinguistic phenomena.
Phonological Word and
Stuttering: A Contrastive Study between English and Spanish
Isabel Vallejo Gomez (1999)
Stuttering, a disorder of oral
language expression, has been studied extensively for decades. Throughout this
time, different explanations have been offered to account for this kind of
speech disorder, from theories that root the cause of stuttering in the
motor-dynamic aspects of speech to others which suggest a psychological
orientation to this condition. This study deals with stuttering and
the concept of phonological word in English and Spanish. Two lines of research, one
in psycholinguistics and the other in linguistics are combined in a comparative
study which attempts to offer a plausible explanation for the causes of
stuttering and its underlying structure. The former will deal with the mental
mechanisms involved in patterns of stuttering, while the latter will focus
primarily on prosodic phonology, offering a theoretical framework in which to
analyse the experimental data. The main purpose of this study, a continuation
of the research proposed by Howell, is to discover whether there are universal
stuttering patterns associated with linguistic structures or whether the
pattern of stuttering is language-specific. Studies focussing on the pattern of
stuttering in English have shown that the stuttering rate is affected by the
function/content word distinction and their position within the phonological
word. In this study, it is argued that since Spanish and English are not
directly related languages, the stuttering patterns observed in English may not
be applicable in Spanish. Although stuttering is a universal phenomenon, some
of the linguistic characteristics it presents are essentially
language-specific.
Speech and Non-speech Auditory
Processing in Children with Dyslexia
Evdoxia Manganari (1998)
Experimental studies have shown
that poor readers are inferior to good readers in some aspects of
speech perception. Two hypotheses have been proposed to account for this
deficit: i) a speech-specific failure in phonological development and ii) a
general deficit in processing auditory information. The aim of the present
study was a) to investigate the perception of plosive consonants in dyslexic
children using identification and discrimination tests, and its relation to
their phonological ability, b) to examine the specificity of a possible deficit
by means of non-speech control stimuli consisting of the F2-transitions alone
and c) to investigate the relationship between performance in speech perception
and a masking task in an attempt to test the hypothesis put forward for
abnormal auditory masking as the underlying cause of the difficulties
experienced by language- and reading-impaired children (Wright, 1997). Two
groups of children matched for age and non-verbal intelligence were selected to
be well separated in reading and spelling ability. The two groups were found
to differ significantly on the speech identification and discrimination tests,
but not on the non-speech conditions. In addition, significant group
differences were obtained in the backward masking condition, but not in forward
and simultaneous masking. The investigation of the relationship between
performances on the masking task and speech perception failed, however, to
provide evidence of a possible link. Although the findings do not support the
General-Auditory-Deficit Hypothesis as the underlying cause of the
reading-impaired childrens’ difficulties, they clearly point to a deficit in
auditory processing in dyslexic subjects.
Dysfluencies Exhibited by
Stutterers: Life-span Differences in Loci and Dysfluency Type
Lea Pilgrim (1998)
Previous work has indicated that
dysfluency types exhibited by stutterers do not remain constant across the life
span (Conture, 1990). Other studies have found that the loci of dysfluencies
also varies as a function of age (Brown, 1945; Bloodstein, 1974). Until now, the
interaction of these two variables, word type and dysfluency type, has not been
investigated within a single study. Here, the interaction of word type and
dysfluency type is explored, within an examination of the differences these
variables exhibit with age. In the current study, it has been
found that the dysfluency type ‘part-word repetition’ is much more likely to be
exhibited by younger stutterers and also that this finding rests predominately
on function words (for example, prepositions, pronouns, modal verbs)
rather than on content words such as nouns, verbs and adjectives. An
interaction between word type and dysfluency type was also found; whole word
repetitions are more likely to occur on content words. Finally, the proportion
of prolongations exhibited on content words was compared to the proportion of
part-word repetitions on function words. The results show a significant
difference which rests on the youngest group of stutterers. These results
identify several significant interactions between word type, dysfluency type
and age. The findings are discussed within the framework of a new model of
stuttering (Au-Yeung, Howell & Pilgrim, in press) and suggestions for
future studies are also proposed in the discussion section of this paper.
The Identification of Reading
and Spelling Development of Greek-speaking Children and Predictions about the
Nature of their Reading Difficulties
Vassiliki Xydi (1998)
This study attempted to examine
reading and spelling development as well as the development of cognitive
measures of Greek-speaking children. These factors were examined before reading
had begun (when the children had finished kindergarten); after initial
instruction had taken place (once the children had completed the first grade of
elementary school) and after reading instruction had been completed (the
children had completed Grade 2). Results from the reading task revealed that
Greek children display rather high reading accuracy and that their spelling was
mainly phonetically acceptable; revealing the complexities of the Greek
orthographic system. The results of the Phoneme Deletion task provided useful
insights into the significance of phonological awareness in relation to reading
and spelling. A picture-naming test showed similar results and Phoneme Deletion
gave insights concerning output phonology and phonological working memory.
Interestingly, Auditory Discrimination, a test often labelled “easy” and a
predictor of reading achievement in other studies, showed very low correlations
with all of the other measures. Analyses of the data clarified issues
concerning the nature of reading and spelling development of children of a
consistent orthography. Firstly, the findings demonstrated the
inadequacies of a model such as Frith’s to account for reading and spelling in
a regular orthography. Secondly, the findings encouraged the prediction that
Greek dyslexic children may suffer from a phonological deficit, thus their type
of dyslexia is characterised as “phonological dyslexia”. Lastly, the most
important factors that predict reading and spelling achievement were found to
be phonological processes, mainly those relating to output
phonology and phonological working memory.
Assessing the Effects of
Speech-reading on Speech
Perception with Sensorineural Hearing Loss – Simulations in Natural Conditions
Peter Lege (1997)
This project might be regarded as
a first attempt to produce video recordings that tried to stimulate sensorineural
hearing loss. The stimulated hearing loss aimed to mimic presbyacusis with a
mild-to-moderate sloping hearing loss in the high frequencies. Within
this framework, the effects of speech-reading on speech perception with
sensorineural hearing loss were investigated. Video recordings of a female
speaker of Southern British English were made in natural rather than laboratory
conditions, namely in a quiet office and in a park surrounded by streets with
heavy traffic. In addition, binaural auditory recordings also helped to give a
more realistic and natural interpretation of the recorded scene. The videotape
produced may also give interested parties the opportunity to appreciate the
impact of sensorineural hearing loss on speech. The
two experiments performed employed five native English speakers with normal
hearing. The first experiment used sets of VCV syllables and investigated the
role of speech-reading with distorted and undistorted speech; with quiet and
noisy backgrounds. Speech-reading did not raise speech intelligibility
significantly when the speech signal was distorted. Surprisingly, quiet and
noisy backgrounds did not make any significant differences in terms of correct
consonant identification. One of the main reasons might be that, owing to the elevated
hearing threshold, differences between quiet and noisy backgrounds were just
reduced. It was also suggested that in previous similar investigations that
real hearing-impaired people achieve lower speech recognition scores than
unimpaired subjects listening to stimulated speech. A
second experiment was designed rather like a pilot experiment and used two
short stories with a distorted speech signal in an audiovisual and
auditory-alone conditions. The results did not allow any reliable analysis. It turned
out that the short stories seemed to be too different to allow a direct
comparison of the results. It might be more appropriate to run pilot
experiments in order to evaluate and obtain short stories which are similar in
terms of content and difficulty. However, a tendency could be observed that
speech-reading might be of benefit for the short stories. It
was concluded that the stimulation of hearing loss needs to be evaluated by
comparing it with hearing-impaired people. Also, additional stimulated
hearing-aid amplification may help to clarify whether quiet-noisy background
conditions are dependent on the actual hearing threshold level and to what
extent spectral smearing and loudness recruitment play a role. If the videotape
turns out to be at least a near-realistic simulation, it could then be used for
presentation purposes with appropriate speech or text material.
Laryngographic Assessment of
Voice Changes with Altered Hydration Status
Julia Selby (1997)
The purpose of this study was to investigate
the effect of mild dehydration on voice quality. Eight healthy male subjects
completed a screening questionnaire and underwent a brief ENT examination to
check that there were no indications of laryngeal pathology or vocal abuse.
They then fasted for a period of eighteen hours and were administered a BIA
test to establish that their body fluids had decreased and that they were
dehydrated. Voice recordings using the Electrolaryngograph were then made.
These consisted of humming, producing sustained vowels at low, comfortable and
high fundamental frequencies, reading a two minute passage and talking
informally for two minutes. The subjects then drank two litres of an
electrolytic drink and waited one hour to become rehydrated again. A second
body fluid measurement was taken to determine that the subjects were rehydrated
and the same test materials were recorded again. The vocal cords were viewed
directly using the Laryngostrobe system when the subjects were dehydrated and
rehydrated. Measures
of vocal cord vibration irregularity, voice fundamental frequency range,
fundamental frequency mode and vocal fold vibration jitter were made using the
Laryngograph (Fourcin and Abberton, 1971). Hydration was found to increase the
mode in the reading task (p=0.002). For all other measures, no significant
effect of hydration was found. Theoretical discussion focuses on the possible
explanations for this and on recommendations for continued research in this
area.
Subjective and Objective Assessment
of the Speech of Post-lingually Deafened Adults. What Makes People "Sound
Deaf"
Caroline Newton (1995)
A combination of subjective
judgements from trained phoneticians and objective measurements indicated
deterioration in the speech of six subjects with an acquired post-lingual
profound hearing loss, compared to the speech of six normally-hearing control
speakers. Deterioration was found in areas including voice quality, rate, Fx
range and fricative production, though a large amount of variation was observed
between the different speakers. Results
taken from the inexperienced listeners showed that they were able to
distinguish the hearing-impaired speakers from the normally-hearing speakers.
This was shown to be statistically significant in a
two-tailed t-test for independent samples at the 0.05 level (p = 0.17 *
10-5). Pearson’s product-moment correlation coefficients were
calculated from the results of the experienced listeners and, where
appropriate, from those of the objective measures. From these
results it was clear that the greatest correlation between these and the
judgementthat someone “sounds deaf” particularly concerned alveolar
frequencies (correlation 0.96). It
was concluded that, as far as these samples of speakers and listeners are concerned,
it is the deviant production of alveolar fricatives that makes someone “sound
deaf”.