Biomedical subjects

S Gatehouse

Publications and source records attributed to S Gatehouse.

At least 55 records · Page 3Linked to original sources

PubMed1991

Costs of investigative protocols for cerebellopontine angle lesions in Scotland.

Efficient use of resources demands evaluation of current practices. This paper presents a prospective evaluation of investigative protocols for cerebellopontine angle lesions. Commonly used protocols vary greatly in their clinical effectiveness and in their costs. The use of appropriate protocols would increase the number of tumours correctly diagnosed each year while also limiting the costs of investigation.

Cerebellar Neoplasms↗

PubMed1990

The output characteristics of an implanted bone conduction prosthesis.

So far, the published guidelines for patient selection for the Audiant implanted bone conduction device have been derived from clinical trial rather than experimental study. Theoretical considerations suggest that the guidelines should be frequency specific; the need for this was investigated in a laboratory study. Two independent measures of the maximum output of the Audiant device using both the body-worn and ear-level amplifiers have been performed on two subjects. These lead to maximum output figures for the device ranging from 15 dB HL at 250 Hz to 60 dB HL at 6000 Hz for the body-worn amplifier, and from 6 dB HL at 250 Hz to 42 dB HL at 6000 Hz for the ear-level amplifier. These results suggest that the ear-level amplifier is suitable only for candidates with essentially normal bone conduction thresholds at frequencies of 1000 Hz and below.

Adult↗

PubMed1990

Whole blood viscosity and red cell filterability as factors in sensorineural hearing impairment in the elderly.

Deficiencies in blood supply can lead to impairments in cochlear function. We have reported significant associations of both measures of whole blood viscosity and derived measures of red cell rigidity with hearing threshold levels in individuals with sensorineural hearing impairments. This paper describes direct measures of red cell filterability in a group balanced across the variables of hearing threshold level and age to facilitate dissociation of the effects of factors correlated with age. After controlling for effects of age, sex and social class, there were strong correlations between whole blood viscosity at high shear rate and hearing threshold levels at 250, 500, and 1,000 and 2,000 Hz. At 4,000 and 8,000 Hz, hearing threshold level was related to red cell filterability. When the data are divided into subgroups by age, the younger age group exhibited a pattern similar to the overall one, but in the older age group the effect of red cell filterability was more apparent, extending down to 1,000 Hz. The data support a strong association between aspects of blood rheology and sensorineural hearing impairment, but in a more complex manner than suggested by previous studies. They imply that there are two processes associated with sensorineural hearing impairment, one of which can be considered as due to bulk rheological properties, while the other appears more related to the properties of individual red cells. The bulk properties are more important at lower frequencies, while the cellular properties are more influential at higher frequencies.

Aged↗

PubMed1990

The contribution of central auditory factors to auditory disability.

Auditory disability increases with both hearing threshold level and age. It is often suggested that some or most of the age effect in auditory disability is underpinned by deficits in central auditory function. A sample of 240 individuals aged between 50 and 75 years was examined to provide a balance across the major variables of hearing level and age. The central auditory indices investigated were: the binaural masking difference, the effects of dichotic competition on the staggered spondaic word tests, the binaural advantage for dichotically presented words, the binaural advantage for dichotically presented sentences, the effect of increasing the rate of presentation of speech, and the effect of nonsense as opposed to sensible sentences. In addition, the non-auditory variables of verbal and non-verbal IQ and the peripheral auditory factors of frequency and temporal resolution were assessed. Auditory disability was assessed using a performance index derived from a sentence identification-in-noise procedure and a procedure containing sense or nonsense sentences. Aspects of self-reported disability were determined using the MRC Institute of Hearing Research's Hearing Disability Questionnaire and the American Hearing Performance Inventory. There were significant correlations between the derived central variables and measured disability after control for hearing threshold levels and age. Central variables were correlated with self-reported disability for only the specific sub-score reflecting disability in localisation. On a multiple regression, the central variables explained 11.1% of the variance in performance index of disability above the 21.1% explained by hearing threshold levels and age.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1990

Factors that influence the benefit from amplification in the elderly.

Many factors have been proposed as potential determinants of the benefit that an individual receives from wearing a hearing aid. In this study, to quantify their relative importance, 54 individuals with symmetrical sensorineural hearing impairment were presented with and without simulated hearing aid characteristics on two measures of disability that were based on identifying words in sentences. Benefit was defined as the difference between the percentage of correct scores with and without the aid characteristics switched into the audio circuit. The factors investigated were age, various peripheral auditory functions, central auditory factors and non-auditory factors such as IQ and personality. Initial correlations suggested a strong relationship between the benefits of amplification and four types of variable: hearing threshold level, frequency resolution, aspects of central function, and the discrepancy in auditory threshold between two methods--a robust psychometric three alternative forced-choice procedure and a conventional audiometric procedure. When the effects of hearing threshold level were partialled out, there remained strong correlations with frequency resolution, co-modulation masking release, and the threshold discrepancy measure. Frequency resolution and threshold discrepancy accounted for a further 21.1% of the variance over the 26.5% of the variance accounted for by hearing threshold level. There were no correlations in this sample of benefit with age, once other aspects had been accounted for. The results indicate a strong role for frequency resolution in the potential benefits from amplification, in addition to central factors such as co-modulation masking release.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1990

Factors influencing consultation for management of hearing disability.

The aim of this study was to compare individuals referred to an Audiology Clinic (consulters) with hearing-impaired individuals in the population who have never sought advice (non-consulters) in order to identify factors which lead some individuals with hearing problems to seek management while others with apparently similar impairments do not seek advice. Two hundred and sixty nine consulters referred to the Audiology Clinic at Glasgow Royal Infirmary were compared with 289 individuals identified in the MRC National Study of Hearing who had never sought advice as an adult about hearing problems. Age, sex, socio-economic group and better-ear hearing threshold were controlled for in all analyses. Consulters were found to have more asymmetrical hearing than non-consulters. They had greater measured disability and reported more disability when their measured disability and impairment were controlled for. They were also more handicapped when impairment and disability were controlled for.

Adult↗

PubMed1990

Response times to speech stimuli as measures of benefit from amplification.

The benefits of management of hearing disability, in particular by provision of a hearing aid, are traditionally assessed by the percentage improvement in performance on a speech identification task. To provide precise and stable results, such procedures require more time than is available in most clinical settings. In any stressed performance, e.g. an impaired individual trying to listen in noise, there is a trading relationship between accuracy and effort (the cost at which accuracy is achieved). If the control of performance naturally spends effort to stabilize high performance, then benefit from amplification may essentially comprise and be measurable as reduction in effort rather than improvement in accuracy. Certainly complaints of hearing disability emphasize fatigue from careful listening. Hence a hearing aid may not only enable hearing impaired persons to hear more of speech but may enable them to hear it more easily, thus reflecting a second dimension to disability and benefit. Ease of listening was investigated using auditory response times to speech stimuli of two levels of structure: single words and sentences. The speech material was presented to 44 experienced hearing aid users (mild to moderate sensorineural hearing impairment). The speech was presented both unaided and aided at presentation levels of 60, 70 and 80 dB SPL and signal-to-noise ratios of quiet and + 5 dB. Response times were taken to the tokens within each list that were correctly identified. Benefit is defined as the decrease in response time from the unaided to the aided condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1990

The role of non-auditory factors in measured and self-reported disability.

The effect of age per se on auditory disability in relation to other non-auditory factors, including personality and IQ, is unclear because of the close link with hearing threshold level. Auditory disability may be assessed in terms of either performance or self-report. It was measured using two tasks identifying words in sentences: (1) sentence identification in noise for spatially separated signal sources, and (2) identification of sensible and nonsensical sentences given at normal and artificially accelerated rates. Self-reported disability was assessed using the MRC Institute of Hearing Research's Hearing Disability Questionnaire and the American Hearing Performance Inventory. The sample of 240 individuals aged 50-75 years was constructed to provide a balance across the major stratification parameters of hearing level and age. In accordance with much of the published literature, the performance indices exhibited significant age effects: for a given hearing threshold level, older individuals are more disabled. Conversely, the indices of self-reported disability exhibit a trend whereby individuals with a given hearing threshold level, report a lower degree of disability with increasing age. There were no significant effects of personality, verbal or non-verbal IQ on the performance indices. However, these variables had large effects on reported disability, increasing the explained variance by approximately 20% more than the variance explained by hearing threshold level and age. Thus, the effect of age has the expected direction for performance-based disability, but for reported disability has the counter-intuitive direction. This finding, together with the additional large significant effects of other nonauditory variables, implies that indices of self-reported disability have to be controlled for these other major determinants if they are to be useful in an overall assessment of auditory disability.

Aged↗

PubMed1990

Determinants of self-reported disability in older subjects.

The effects of hearing threshold levels, age, personality, and IQ on indices of self-reported disability/handicap derived from the Hearing Performance Inventory and the Institute of Hearing Research Hearing Disability Questionnaire have been investigated in a sample of 240 individuals with bilateral, symmetric sensorineural hearing, which was efficiently balanced across hearing threshold level and age. The results show significant effects of age, IQ, and, in particular, personality on many aspects of reported disability/handicap, with different relative contributions for females and males. It is possible to account for between 42 and 50% of the variance in most of the disability/handicap indices. Around 5% is accounted for by age and between 12 and 22% by aspects of personality. These findings suggest that the effects of age, IQ, and personality should be considered and incorporated into any practical application using self-assessment instruments.

Age Factors↗

PubMed1990

Fundamental issues in self-assessment of hearing.

The history of self-assessment for hearing is reviewed from its beginning use in the 1930s to its emerging importance in the 1980s. It is presented as a more systematic method for interviewing the patient, and although it does not always agree with pure-tone findings, it should be recognized as a useful assessment method to be used in combination with other measures of hearing. The uses for self-assessment, psychometric concerns, issues in the definition of hearing domains (disorder, impairment, handicap, disability), and new frontiers also are discussed in this overview article.

Hearing Disorders↗

PubMed1990

The Chief Scientist reports ... hearing research at the Medical Research Council Institute of Hearing Research (Scottish Section).

In addition to conducting research with the Section's own resources from the MRC and the Scottish Home and Health Department, the Section stimulates collaborative clinical research with the University and Health Service Departments. This work would be unlikely to take place without the existence of the Scottish Section of the MRC Institute of Hearing Research. Its presence has contributed to the continuing recognition of the Royal Infirmary Departments as an attractive centre for postgraduate training by both British and overseas graduates, leading in time to a substantial body of clinical research in ENT. This close interlinking between a research unit and an academic otolaryngology department is most unusual in the UK and encourages a programme which contains elements of readily applicable clinical research. Clinical and scientific environments are mutually stimulating, so the Section also incorporates in Glasgow some more fundamental laboratory-based studies also, which aim to investigate underlying issues in the diagnosis and management of otological conditions.

Academies and Institutes↗

PubMed1989

Blood viscosity and hearing levels in the Caerphilly Collaborative Heart Disease Study.

Data from 342 men who are participants in the Caerphilly Collaborative Heart Disease Study were used to replicate a previous report of a significant relationship between measures of whole-blood viscosity and hearing levels in persons with sensorineural hearing impairment. In the unselected data, there were significant relationships between measures of whole-blood viscosity at high shear rates and hearing threshold levels at 2000 and 4000 Hz, even after accounting for the effects of age and socioeconomic group. In a subset of the data containing 124 persons selected on the basis of likely sensorineural hearing impairment, there were significant relationships between whole-blood viscosity and hearing level at all frequencies, with stronger effects at the higher frequencies. The data support the contention of a potentially important relationship between whole-blood viscosity and sensorineural hearing impairment.

Audiometry, Pure-Tone↗

PubMed1989

Apparent auditory deprivation effects of late onset: the role of presentation level.

Silman and colleagues [J. Acoust. Soc. Am. 76, 1347-1362 (1984)] have reported an apparent effect of late auditory deprivation; this presents as loss of discrimination over time in the unaided ear of individuals using a single hearing aid fitted in middle age. In a replication of the basic effect, the influence of presentation level was examined in 24 monaurally aided subjects. The effect was reversed at presentation levels below about 75 dB SPL. The ear that is normally aided performs better at high presentation levels, while, at lower presentation levels, the converse is true. Thus it appears that a form of selective adjustment takes place in a particular part of the dynamic range, at least in ears with a dynamic range limited by a sensory hearing loss. If this interpretation is correct, there are important implications for research on perceptual learning and for the time course of evaluation in hearing aid provision.

Audiometry, Pure-Tone↗

PubMed1989

Hearing in chronic suppurative otitis media.

In individuals with chronic otitis media, mixed hearing impairments are common but it is unclear whether the raised bone conduction thresholds are a reflection of the pathologic process affecting the inner ear or a combination of the high prevalence of sensorineural hearing impairments in the population along with the artificial elevation of bone conduction thresholds associated with a conductive defect. A total of 395 ears with chronic otitis media but without cholesteatoma were studied. In them, once the artificial elevation (Carhart effect) of the bone conduction thresholds, which occurs whenever there is an abnormality of the sound conduction mechanism, had been taken into account, there was no difference in the bone conduction thresholds compared with those in 920 control ears. In addition, in 100 instances, the contralateral ear was normal and there was no difference in the bone conduction thresholds between the diseased and the normal ears. Raised bone conduction thresholds in chronic otitis media are considerably likely to reflect both the Carhart effect and the high prevalence of sensorineural impairments, rather than disease damage to the inner ear.

Auditory Threshold↗

PubMed1989

A pseudo free-field measure of auditory disability.

Conventional measures of auditory disability via speech identification scores are usually monaural, or occasionally, diotic. Circumstances of everyday listening usually contain stereophonic (dichotic) cues, whilst such listening situations can be tested in a free field environment they are difficult to standardize and calibrate. A procedure has been developed by recording the signals from two Zwislocki couplers in a KEMAR mannikin to produce a headphone-presented set of speech material containing the important dichotic cues present in free field listening. This enables readily calibrated and experimentally controllable conditions to be set up to measure aspects of auditory disability and, for example, its alleviation via amplification. Two examples of the use of the test are provided: (i) the assessment of the benefits of the presence of stereophonic cues on speech identification in both the real free field and simulated conditions, and (ii) the benefits of monaural and binaural provision of amplification of hearing impaired people in directional listening situations.

Hearing Loss↗

PubMed1989

Limitations on insertion gains with vented earmoulds imposed by oscillatory feedback.

When an earmould is vented, either to relieve sensations of blockage or to modify the frequency response of a hearing aid system, the gain setting at which feedback occurs is lowered. Although this principle is widely appreciated, the typical gains at which feedback occurs have received little systematic study and vented earmoulds are still prescribed on largely rule-of-thumb, or trial and error basis. In a laboratory study on a KEMAR mannikin the effects for hearing aids with gains up to 64 dB were studied. The acoustical stimuli were varied (using speech-shaped noise, wide-band noise and narrow bands of noise), as were the size of the parallel vent (0.8 and 2.0 mm) and the orientation of the microphone on the aid (forward-facing and downward-facing). The results suggest that: a forward-facing microphone is less susceptible to oscillatory feedback than a downward-facing one; while a 2 mm vent leads to more feedback limitations than a 0.8 mm vent, the smaller vent is more than a 'pressure vent', having some acoustical effects; and the spectrum of the ambient acoustics can markedly reduce the available gain before the onset of oscillation, e.g. from greater than 40 dB to less than 20 dB gain.

Ear↗

PubMed1988

Medical management of active chronic otitis media: a controlled study.

About 2 per cent of adults have active chronic otitis media, the majority being managed by medical means. Previous controlled studies have been unable to show benefit from any medication, including systemic or topical antibiotics, but the effect of the addition of topical steroids to the latter has never been evaluated. One hundred and sixty three adults with active chronic otitis media were randomly allocated to receive either antibiotic/steroid ear drops or placebo therapy over a 4-6 week period. Fifty-two per cent of ears receiving active therapy, as opposed to 30 per cent on placebo therapy (p less than 0.05), became otoscopically inactive if compliance to medication was greater than 70 per cent. However, when there was an open mastoid cavity, active therapy was no more successful than placebo. Though gentamicin was the antibiotic used, there was no evidence of ototoxic inner ear damage. Surprisingly, correlation between clinical activity and patient report of a discharge was poor. Forty per cent of both treatment groups considered that their ear had become dry following therapy and these were not the same patients whose ears had become otoscopically inactive.

Administration, Oral↗

PubMed1988

An audiovisual test of hearing disability using free-field sentences in noise.

An audiovisual test, using BKB sentences in noise, has been developed to assess hearing disability, unaided and aided with a hearing aid(s), in severely hearing-impaired individuals. After a single practice list, no significant further increases in performance were detected. The test is reproducible within and between test sessions.

Hearing Aids↗