Biomedical subjects

S C Purdy

Publications and source records attributed to S C Purdy.

16 recordsLinked to original sources

PubMed2006

Electrophysiological and behavioral evidence of auditory processing deficits in children with reading disorder.

OBJECTIVE: The aim of the research was to investigate auditory processing abilities in children with reading disorders using electrophysiological and behavioral tasks. METHODS: Differences in auditory processing between control, compensated (age appropriate reading skills with a history of reading disorder), and reading disordered groups were systematically investigated. RESULTS: The reading disorder group had significantly lower results than control and compensated reader groups for most tests in the reading and auditory processing test battery. All children with a reading disorder did not pass at least one behavioral test of auditory processing, and hence would be diagnosed clinically as having an auditory processing disorder (APD). The reading disorder group also had significantly smaller /ga/-evoked mismatch negativity (MMN) area than the control group. Compensated and control groups had similar results for the electrophysiological and behavioral auditory processing tests. Correlation analyses showed that reading fluency and accuracy and nonword scores (measured using Castle and Coltheart's word/nonword test) correlated significantly with most APD measures. CONCLUSIONS: The general profile of auditory processing deficits in children with reading disorder was a combination of deficits on frequency patterns (i.e. frequency pattern test) and absent or small /ga/-evoked MMN. Significant results from the correlation analyses support the co-morbidity of reading and auditory processing disorders. SIGNIFICANCE: Children with reading disorders are likely to have auditory processing disorders.

Acoustic Stimulation↗

PubMed2001

Frequency specificity of the human auditory brainstem and middle latency responses using notched noise masking.

This study investigated the frequency specificity of the auditory brainstem and middle latency responses to 80 and 90 dB ppe SPL 500-Hz and 90 dB ppe SPL 2000-Hz tonebursts. The stimuli were brief (2-1-2 cycle) linear-gated tonebursts. ABR/MLRs were recorded using two electrode montages: (1) Cz-nape of neck and (2) Cz-ipsilateral earlobe. Cochlear contributions to ABR wave V-Na and MLR waves Na-Pa and Pa-Nb were assessed by plotting notched noise tuning curves which showed amplitudes and latencies as a function of center frequency of the noise masker [Abdala and Folsom, J. Acoust. Soc. Am. 97, 2394 (1995); ibid. 98, 921 (1995)]. Maxima in the response amplitude profiles for the ABR and MLR to 80 dB ppe SPL tonebursts occurred within one-half octave of the nominal stimulus frequency, with minimal contributions to the responses from frequencies greater than one octave away. At 90 dB ppe SPL, contributions came from a slightly broader frequency region for both stimulus frequencies. Thus, the ABR/MLR to 80 dB ppe SPL tonebursts shows good frequency specificity which decreases at 90 dB ppe SPL. No significant differences exist in frequency specificity of: (1) ABR wave V-Na versus MLR waves Na-Pa and Pa-Nb at either stimulus frequency or intensity; and (2) ABR/MLRs recorded using the two electrode montages.

Auditory Threshold↗

PubMed2001

Technology, expectations, and adjustment to hearing loss: predictors of hearing aid outcome.

This study examined the influence of technology, demographic factors, and prefitting expectations, attitudes, and adjustment to hearing loss on hearing aid outcome. Clients obtaining new hearing aids completed questionnaires measuring personal adjustment to hearing loss, expectations of and attitudes toward hearing aids, and hearing aid benefit. Eighty-one percent of the 200 subjects completing the prefitting questionnaires returned questionnaires evaluating hearing aid outcome. Factors affecting hearing aid use, overall satisfaction, and benefit were investigated using regression analyses. Higher use time was associated with higher prefitting expectations and greater acceptance of hearing loss. Greater benefit in easy and difficult listening situations was predicted by higher prefitting expectations. Multiple-memory hearing aids produced higher satisfaction. Benefit was greater for multiple-memory, multiple-channel, and wide dynamic range compression aids. Findings were consistent with previous studies showing positive outcomes for newer technologies but also showed that two subjective factors, prefitting hearing aid expectations and acceptance of hearing loss, significantly influenced hearing aid outcome.

Acoustic Stimulation↗

PubMed1998

Investigation of the profile of hearing aid performance in experienced hearing aid users.

OBJECTIVE: A shortened version of the 66-item Profile of Hearing Aid Performance (PHAP), consisting of the 24 items from the Abbreviated Profile of Hearing Aid Benefit, was evaluated as an alternative to the full PHAP questionnaire as a measure of hearing aid performance. Objectives were to: 1) statistically determine factors underlying Abbreviated PHAP (APHAP) scores; 2) recommend modifications to the questionnaire, if indicated by the factor analysis; 3) compare scores for the PHAP and APHAP; and 4) determine the suitability of the abbreviated questionnaire for New Zealand hearing aid users. The relationship between hearing aid performance and subjective variables and other measures of hearing aid success also was investigated. DESIGN: PHAP data, hearing aid satisfaction ratings, and reported daily hearing aid use were obtained from experienced adult hearing aid users. Factor analysis was carried out for the 24 APHAP items, and two items were excluded because of low factor loadings. After this modification, APHAP and PHAP scores were compared. Pearson's correlation values were determined for PHAP and APHAP data and degree of hearing loss, hearing aid satisfaction, and hours of hearing aid use. RESULTS: APHAP hearing aid performance was better described as three factors rather than four subscales. PHAP and APHAP results were consistent with previous studies and showed that hearing aid performance was best for easy listening situations and poorest for noisy and/or reverberant conditions. Similar trends were seen for PHAP and APHAP data. APHAP scores were correlated with hours of hearing aid use and overall hearing aid satisfaction. CONCLUSIONS: A shortened, 22-item APHAP is a preferred alternative to the full PHAP, producing data representing several dimensions of hearing aid performance. Modified APHAP scores can be used together with overall satisfaction and estimates of daily hearing aid use to measure success with hearing aids.

Adult↗

PubMed1997

Evaluation of hearing aid benefit using the Shortened Hearing Aid Performance Inventory.

To date, little quantitative data regarding hearing aid benefit has been produced in New Zealand. The 38-item Shortened Hearing Aid Performance Inventory (SHAPI) was administered by mail to hearing aid clients aged over 50 years who had been fitted with hearing aids in the previous 2 years. Based on subjects' responses, three items with low applicability were dropped from the analysis. The overall mean rating was higher than that of comparable studies, indicating a lower hearing aid benefit level. Mean rating was positively correlated with subject age but was not correlated with weekly hours of use. Factor analysis revealed three significant factors that were consistent with factors identified in previous studies: listening under favorable conditions, listening to speech in background noise, and listening with reduced cues. Consistent with previous studies, internal consistency was very high.

Aged↗

PubMed1996

Hearing aid use and benefit and uptake of aural rehabilitation services by New Zealand hearing aid wearers.

AIM: To provide the first extensive survey in New Zealand of hearing aid use and benefit and the accessibility of Hearing Association services. METHOD: A mail-out questionnaire was used to survey 197 Auckland adult hearing aid wearers regarding patterns of hearing aid use and benefit and the accessibility of Hearing Association aural rehabilitation services. RESULTS: Hearing aid benefit was moderate and was not related to age or hearing aid use variables. Knowledge and usage of local rehabilitation services was limited. Perceived functions of the Hearing Association included adult audiometry and counselling. Respondents wanted assistance with hearing aid management and assistive listening devices. Physical access, financial and time constraints were seen as barriers to using rehabilitative services. DISCUSSION: It appears that there is not a simple relationship between perceived benefit or satisfaction and the amount of time people wear their hearing aids. The low level of awareness and participation in Hearing Association services is consistent with the underutilisation of such services found previously.

Adult↗

PubMed1995

Outcomes of cochlear implants for New Zealand children and their families.

Six children with multichannel cochlear implants and their families were evaluated by means of multiple measures to determine the impact of the cochlear implant on the child's speech perception, language, communication mode, and behavior and on the parents' stress levels. The children showed quite variable improvements in speech perception with the implant. One child showed marked improvements in language 6 months after implantation. Two of the children had behavior problems preimplantation that showed some improvement after implantation. Parenting stress was very high in some families, but on average, stress was lower and social support networks were more extensive than those previously reported in studies of parents of deaf children in the United States.

Child↗

PubMed1992

Reported use of communication strategies by SHHH members: client, talker, and situational variables.

Two hundred and twelve members of the Self Help for Hard of Hearing People (SHHH) organization completed a survey that evaluated their use of communication strategies. Reported use of strategies was correlated with attitudinal variables and social-interaction indices. On average, subjects agreed most strongly with questionnaire items stating they would ask a talker to repeat a misperceived utterance. They agreed less strongly with items stating they would ask the talker to restructure or elaborate an utterance. Subjects agreed strongly that they would use the communication strategies with familiar talkers, and less strongly that they would use them with unfamiliar talkers. Subjects who appeared less likely to say nothing after misperceiving an utterance were more likely to disagree that they were frustrated with their speechreading skills, and they appeared less likely to avoid social interactions. Subjects who indicated a greater likelihood of using anticipatory strategies, such as reviewing potential vocabulary before an appointment, were on average more likely to avoid social interactions. They also agreed more strongly that poor speechreaders appear less intelligent.

Adult↗

PubMed1992

Reliability, sensitivity and validity of magnitude estimation, category scaling and paired-comparison judgements of speech intelligibility by older listeners.

This study investigated the reliability, sensitivity, and validity of speech intelligibility judgments for hearing aid evaluation. Subjects aged 60-87 years judged the intelligibility of sentences using either magnitude estimation, category scaling or paired comparisons. The 60+ age group was chosen as representative of the majority of hearing aid wearers. Speech recognition scores for Central Institute for the Deaf (CID) sentences and Northwestern University Auditory Test No. 6 (NU-6) words were also obtained. The speech was bandpass filtered using filter settings that produce a monotonic increase in predicted intelligibility based on articulation index theory. Speech recognition scores and intelligibility judgments were obtained for each of eight filter conditions. Test-retest reliability was poorest for paired comparisons and CID sentence scores. There were no differences in sensitivity among the three psychophysical procedures. Intelligibility judgments and NU-6 scores were more sensitive than CID sentence scores to differences among conditions. The results indicated that intelligibility judgments are valid measures of speech recognition.

Acoustic Stimulation↗

PubMed1991

Frequency-specific auditory brainstem responses relationship to behavioural thresholds in cochlear-impaired adults.

Auditory brainstem response (ABR) thresholds to ipsilaterally masked tone pip stimuli were obtained from three groups of hearing-impaired subjects. Using high-pass (for 500-Hz tone pips) and notched noise (for 1-, 2- and 4-kHz tone pips), ABR thresholds in subjects with low-frequency, high-frequency or flat cochlear hearing losses were compared to conventional pure-tone audiometric thresholds. A strong positive relationship was found between ABR and behavioural threshold elevation. Absolute ABR thresholds at 500 Hz were significantly higher than those at other frequencies. The results of this study indicate that frequency-specific ABR testing can provide an approximation of both degree and configuration of cochlear hearing losses in adults. Further refinements of testing and judging procedures are needed however to reduce the variation evident in our results and thus achieve the accuracy required for most clinical applications.

Adult↗

PubMed1990

Effects of repair strategies on visual identification of sentences.

This investigation determined whether information elicited by repair strategies enhances an individual's ability to lipread a misperceived sentence. Five groups of subjects were each assigned one of five repair strategies: (a) asking the talker to repeat a sentence, (b) simplify it, (c) rephrase it, (d) say an important keyword, and (e) speak two sentences. Subjects viewed sentences spoken by six different talkers. When a subject did not recite a sentence verbatim, the talker performed the assigned repair strategy and then repeated the original sentence. A control group of subjects saw only the original sentence repeated twice. All five test groups demonstrated a significantly greater improvement for the second presentation score (referenced to the first presentation score) than the control group. The benefits provided by the repair strategies were independent of the talker, and benefits did not differ significantly among the groups.

Adult↗

PubMed1989

Frequency-specific auditory brainstem responses. Effective masking levels and relationship to behavioural thresholds in normal hearing adults.

Ipsilateral masking levels and normal thresholds for tone pip auditory brainstem responses (ABRs) were investigated in normal subjects for the purpose of establishing recording parameters and norms for frequency-specific tone pip ABR testing. White noise was found to effectively mask ABRs to tone pips at mean signal-to-noise ratios of between -1 and -5.5 dB [dB peak-equivalent (pe) SPL/dB SPL] depending on the tone pip frequency. ABR thresholds were established for tone pips in the presence of ipsilateral masking with high-pass filtered noise for 50-Hz tone pips and notched noise for tone pips from 1,000 to 4,000 Hz, at a nominal signal-to-noise ratio of -5 dB (i.e. with the noise SPL measured prior to filtering). Thresholds occurred between 28.6 and 36.6 dB pe SPL, equivalent to 4.4-8.8 dB nHL. ABR thresholds for masked and unmasked tone pips did not differ significantly.

Adolescent↗

PubMed1982

The minimum detectable duration of auditory signals for normal and hearing-impaired listeners.

The minimum detectable duration of a brief burst of noise and a brief gap in a noise were measured by the two-alternative forced-choice method. For all listeners the minimum detectable duration of a burst was shorter than the minimum detectable duration of a gap at equal signal-to-noise ratios. For 12 listeners with normal hearing, the average minimum detectable duration of a burst with a 10-dB signal-to-noise ratio was 1.2 msec, whereas the average of a gap at the same signal-to-noise ratio was 4.2 msec. Nine of ten hearing impaired listeners required longer durations, whether for bursts or gaps, than the average of normal listeners. These nine impaired listeners had slower time constants than any of the normal listeners. Both the rise and decay of auditory sensation in the impaired listeners were therefore abnormally slow.

Acoustic Stimulation↗

PubMedDate not supplied

Auditory evoked potentials as measures of plasticity in humans.

There is increasing evidence from animal studies for plasticity of auditory function. This has prompted research to determine whether such plastic changes occur in adults and children with hearing disorders. Behavioural measures such as speech perception scores do show improvements after hearing aid fitting and cochlear implantation. Several studies have also shown changes in cortical auditory evoked potentials after cochlear implantation and after auditory training. These studies indicate that improvements in speech perception ability are associated with changes in the central auditory system, particularly at the cortical level.

Cochlear Implantation↗

PubMedDate not supplied

Influence of acquisition parameters on the measurement of click evoked otoacoustic emissions in neonates in a hospital environment.

There is much interest in the introduction of a universal neonatal hearing screening programme. Screening programmes using high-risk criteria have been used for some time, but 50 per cent of deaf and hearing-impaired neonates are not identified because they are not classified as high risk for hearing impairment at birth. Otoacoustic emission (OAE) measurement is widely regarded as a technique likely to be suitable for universal hearing screening. To examine this, otoacoustic emissions were measured from 351 neonate ears at a large maternity hospital. Of particular interest were the practicalities of recording OAE in a hospital environment, the establishment of an appropriate age at which screening should be performed on neonates and investigation of the relative advantages of different recording techniques. Main findings were: (1) low OAE levels relative to noise during the first 24 to 48 hours post partum; (2) lower OAE signal to noise levels in low frequencies irrespective of age; (3) increase of overall signal to noise ratio in frequencies above 1 kHz through the use of a shortened response window; and (4) OAE recording could be performed easily in mothers' hospital rooms prior to discharge.

Acoustic Stimulation↗

PubMedDate not supplied

Does the presentation of audiometric test data have a positive effect on the perceptions of workplace noise and noise exposure avoidance?

Research and 'common knowledge' has for many years accepted that education and feedback supplied to individuals during and immediately after workplace health assessments provides valuable information to workers about their health. Further, if more relevant and detailed information could be supplied then awareness and preventative action may increase proportionately. This research carried out with a rural Australian population has shown that preventative action did not increase in proportion to a corresponding increase in the amount and variety of information provided in connection with hearing health status. Two research groups underwent hearing tests, both with pure tone audiometry (PTA) while the second group also underwent otoacoustic emission (OAE) testing. Test results were presented to the subjects at the conclusion of their test session. An analysis of questionnaire responses at six week and twelve months follow up showed that more information did not result in increased preventative action. Barriers seem to exist such that individuals feel that they are not able to effectively act to reduce overall noise exposure. While self-efficacy initially increased, it declined to close to its initial value over the longer period. Other measures such as perceived susceptibility to hearing loss and the benefits of exposure reduction significantly increased and remained at the same increased level after twelve months. So, while overall awareness of noise and the risks of exposure were increased after both types of hearing test there was no increased hearing health benefit due to additional testing and hearing information.

Adult↗