Search PubMed⌕ Search

Biomedical subjects

S Gatehouse

Publications and source records attributed to S Gatehouse.

At least 19 recordsLinked to original sources
PubMed1999

Sound localization in noise in normal-hearing listeners.

The ability to localize a click train in the frontal-horizontal plane was measured in quiet and in the presence of a white-noise masker. The experiment tested the effects of signal frequency, signal-to-noise ratio (S/N), and masker location. Clicks were low-pass filtered at 11 kHz in the broadband condition, low-pass filtered at 1.6 kHz in the low-pass condition, and bandpass filtered between 1.6 and 11 kHz in the high-pass condition. The masker was presented at either -90, 0, or +90 deg azimuth. Six signal-to-noise ratios were used, ranging from -9 to +18 dB. Results obtained with four normal-hearing listeners show that (1) for all masker locations and filtering conditions, localization accuracy remains unaffected by noise until 0-6 dB S/N and decreases at more adverse signal-to-noise ratios, (2) for all filtering conditions and at low signal-to-noise ratios, the effect of noise is greater when noise is presented at +/- 90 deg azimuth than at 0 deg azimuth, (3) the effect of noise is similar for all filtering conditions when noise is presented at 0 deg azimuth, and (4) when noise is presented at +/- 90 deg azimuth, the effect of noise is similar for the broadband and high-pass conditions, but greater for the low-pass condition. These results suggest that the low- and high-frequency cues used to localize sounds are equally affected when noise is presented at 0 deg azimuth. However, low-frequency cues are less resistant to noise than high-frequency cues when noise is presented at +/- 90 deg azimuth. When both low- and high-frequency cues are available, listeners base their decision on the cues providing the most accurate estimation of the direction of the sound source (high-frequency cues). Parallel measures of click detectability suggest that the poorer localization accuracy observed when noise is at +/- 90 deg azimuth may be caused by a reduction in the detectability of the signal at the ear ipsilateral to the noise.

Adult↗
PubMed1996

Test-retest reliability of loudness scaling.

OBJECTIVE: Establish the test-retest reliability of loudness scaling using a bounded category rating method. DESIGN: The individual loudness functions were investigated in three groups of listeners: seven normal-hearing listeners age 18 to 35 yr, five normal-hearing listeners aged 57 to 84 yr, and five listeners aged 54 to 82 yr with bilateral sloping sensorineural hearing loss. Test-retest reliability was investigated by determining the intralistener, between-session standard deviation. RESULTS: The pattern of test-retest reliability was similar across all three groups. It improved as the intensity of the stimulus increased: 7 dB at the first quartile of the loudness function, and 3 dB at the third quartile. Two to four runs of the task appear to be sufficient to obtain a stable loudness function, and it was shown that an exponential function provided a better goodness of fit than a linear function (r2: 0.99 compared with 0.94). CONCLUSIONS: Loudness scaling is a longer test than most conventional suprathreshold measures and requires special equipment. However, it has good test-retest reliability and provides more information on the loudness function that might be useful in the fitting of nonlinear hearing aids. The data show that an exponential function provides a good fit to the loudness growth data, and should probably be incorporated into fitting algorithms associated with loudness scaling.

Adolescent↗
PubMed1996

Report of the Eriksholm Workshop on auditory deprivation and acclimatization.

The terminology used in studies documenting changes in auditory performance following fitting of hearing aids has been diverse. Definitions for the auditory deprivation effect and auditory acclimatization are offered as a first step in rationalization. Two statements summarize current knowledge concerning auditory deprivation effects and auditory acclimatization, as well as considering the potential implications for research, field trial and clinical practice applications. Potential areas for future research are identified.

Auditory Perception↗
PubMed1996

Measuring patient benefit from otorhinolaryngological surgery and therapy.

The Glasgow Benefit Inventory (GBI) is a measure of patient benefit developed especially for otorhinolaryngological (ORL) interventions. Patient benefit is the change in health status resulting from health care intervention. The GBI was developed to be patient-oriented, to be maximally sensitive to ORL interventions, and to provide a common metric to compare benefit across different interventions. The GBI is an 18-item, postintervention questionnaire intended to be given to patients to fill in at home or in the outpatient clinic. In the first part of the paper, five different ORL interventions were retrospectively studied: middle ear surgery to improve hearing, provision of a cochlear implant, middle ear surgery to eradicate ear activity, rhinoplasty, and tonsillectomy. A criterion that was specific to the intervention was selected for each study, so that the patient outcome could be classified as above and below criterion. In all five interventions, the GBI was found to discriminate between above- and below-criterion outcomes. The second part of the paper reports on the results and implications of a factor analysis of patient responses. The factor structure was robust across the study, and so led to the construction of subscales. These subscales yield a profile score that provides information on the different types of patient benefit resulting from ORL interventions. The GBI is sensitive to the different ORL interventions, yet is sufficiently general to enable comparison between each pair of interventions. It provides a profile score, which enables further breakdown of results. As it provides a patient-oriented common metric, it is anticipated that the GBI will assist audit, research, and health policy planning.

Adult↗
PubMed1995

Speech discrimination in patients with Bell's palsy and a paralysed stapedius muscle.

The contraction of the stapedius muscle results in a frequency dependant attenuation of sound through the middle ear. Idiopathic facial nerve paralysis (Bell's palsy) usually results in a paralysis of the stapedius muscle. This prospective study included 119 patients presenting with Bell's palsy over an 18-month period. After applying exclusion criteria, 80 patients with normal pure-tone audiograms underwent speech audiometry. This was performed on presentation and after recovery of the facial nerve palsy. Fifty-six patients (70%) with an absent stapedius reflex showed marked 'roll-over' from means of 98-49% on their speech audiogram. This resolved completely with recovery of the facial nerve palsy and return of the stapedial reflex. To determine whether this effect was due primarily to the paralysis of the stapedius muscle or to an associated polyneuropathy, a second study on six normal patients was done. These patients had both ears (12 in total) tested with speech filtered to simulate a paralysed stapedius muscle. This resulted in a mean 'roll-over' from 90.9 to 59.9%. The magnitude of this roll-over (31%) was only two-thirds of that seen in Bell's palsy patients (49%) with the difference between these means statistically significant (P < 0.05). This suggests that Bell's palsy, usually considered a mononeuropathy, involves certain of the auditory fibres of the eighth nerve and is a polyneuropathy. Stapedius function is important in speech discrimination at higher levels of sound intensity such as speech in noise and severing the stapedius tendon in stapes surgery may affect speech discrimination after successful surgery.

Adult↗
PubMed1995

The effect of recurrent tonsillitis and tonsillectomy on growth in childhood.

The aim of this study was to determine if children with recurrent tonsillitis are smaller than expected before tonsillectomy and if they have an altered height or weight gain 1 year post-operatively. All (204) children attending the hospital for tonsillectomy with or without adenoidectomy had their height and weight measured pre-operatively and 1 year after operation. The results of 2204 children in local schools were used as a control population. Analysis was by comparison of each population with the Tanner charts. This study suggests that our population of children listed for tonsillectomy were not lighter or smaller than expected before operation but that one year after tonsillectomy, there was an increase in their weight gain. The height gain was no different than expected after operation. Overweight seems to be a medium term complication of tonsillectomy. It may be necessary to redefine the indications for tonsillectomy in children who are already obese.

Body Constitution↗
PubMed1995

Idiopathic epistaxis, haemostasis and alcohol.

Recent studies have suggested a link between antiplatelet medications and alcohol in the aetiology of acute adult epistaxis. The possibility that adult epistaxis may be associated with alcohol induced platelet dysfunction has not previously been investigated. This study evaluated primary haemostasis in 50 adult patients with idiopathic epistaxis. A detailed alcohol history was recorded and the Simplate bleeding time device was used to test haemostatic function. Forty-six per cent of patients were found to have an abnormality of primary haemostasis. Prolongation of the bleeding time was significantly associated with a history of alcohol use. The effect of alcohol on the bleeding time duration was significant (P < 0.001) even at low levels of intake of between 1 and 10 units per week. Although prevalent in the study group (42%) the use of non-steroidal anti-inflammatory drugs did not confer a significant additional risk of increased bleeding time. These findings support the importance of alcohol induced haemostatic abnormalities in the aetiology of adult epistaxis.

Adult↗
PubMed1995

Changes in intensity discrimination following monaural long-term use of a hearing aid.

Previous work has shown that a normally aided ear tested without the hearing aid is better able to identify speech-in-noise than the unaided ear at high sound levels, while performance for the unaided ear is superior at lower sound levels [S. Gatehouse, J. Acoust. Soc. Am. 86, 2103-6 (1989); J. Acoust. Soc. Am. 92, 1258-68 (1992)]. This effect was further explored using intensity discrimination for complex stimuli. Stimuli were half-octave bandpass-filtered tone complexes centered at 0.25 and 3 kHz. Four bilateral, symmetric hearing-impaired listeners with mean HL of 24 dB at 0.25 kHz, and 58 dB at 3 kHz were tested. Intensity discrimination was performed across the dynamic range of the listeners. At sound-pressure levels greater than 85 dB, the normally aided ear tested without the aid was more sensitive to changes in intensity than the unaided ear, whereas at lower levels, the converse occurred. This pattern was observed only for the 3-kHz center frequency, and not for the 0.25-kHz center frequency. Insertion gain measurements using the aids at normal volume showed an average of 20 dB gain at 3 kHz, and -2 dB gain at 0.25 kHz. The changes in intensity discrimination in the normally aided ear are consistent with the frequency-gain characteristics of the hearing aid, and suggest that a change in intensity coding occurred.

Adolescent↗
PubMed1995

The value of routine in-the-ear measurement of hearing aid gain.

When selecting the frequency response of a hearing aid, a target is usually selected using a predictive formula from the international literature. Nowadays real ear measurements can readily be carried out to ensure that the real ear gain closely matches the prescribed target. Such measurements are usually only carried out on a subset of patients fitted in the UK, though it has been suggested that they should be carried out on all hearing aid prescriptions. Real ear insertion gains were measured on 319 first-time National Health Service (NHS) hearing aid issues. A total of 181 (57%) failed to come within 10 dB of the target gain at one or more frequencies between 0.25 and 3 kHz. Though there were audiometric differences between those who achieved satisfactory gain and those who did not, there was too much overlap between groups to make any audiometric index or combination of indices of value in predicting the likelihood of failure to achieve target gain. Sixty-eight patients with inadequate real ear gain were invited to attend for alterations to their hearing aid prescription. Twelve (18%) were fitted with a high frequency aid, while the rest were managed by alterations to their NHS aid or to the earmould and tubing. After appropriate changes, 58 (85%) achieved a satisfactory gain. The routine use of real ear insertion gains in all hearing aid fittings would result in many patients having a more accurately fitted hearing aid. As the majority of prescriptions could be adequately improved using NHS hearing aids, the effects on the hearing aid budget would be relatively small.

Adult↗
PubMed1994

Components and determinants of hearing aid benefit.

This study investigates the measured and perceived disabilities and handicaps and associated auditory performance in 309 first-time hearing aid candidates. The results suggest that both disability and hearing aid benefit may be divided into separate components having particular and separate relationships to predictor variables in terms of both auditory and nonauditory characteristics. This division leads to a better understanding of the problems associated with a hearing impairment and their alleviation (or lack of) by provision of a hearing aid. In addition, the results support the development of more appropriate speech identification measures and suggest a potentially important role for measures of the temporal properties of the impaired auditory system.

Acoustic Stimulation↗
PubMed1994

Estimation of the benefit of bone-anchored hearing aids.

Implantable bone conduction hearing aids are a valuable alternative to conventional aids for those who cannot use a conventional air conduction aid or find it difficult to use because of an aural discharge, most commonly due to chronic otitis media. Previously reported series of the use of a bone-anchored hearing aid (BAHA) come from the originators of this device, and an independent report of their benefit and use, especially in previous air conduction aid users, would be of value. Twenty-three patients were evaluated at least 6 months after implantation of a BAHA. All 7 previous bone conduction aid users were delighted with their BAHA, reporting increased comfort and hearing benefit that was backed by audiometric evidence. Of the 16 individuals who previously used an air conduction aid, 11 (69%) were delighted users of their BAHA. Unfortunately, the other 5 (31%) reverted to solely using their air conduction aid. There was no obvious predictor as to how these individuals might have been identified prior to implantation. In particular, their pure tone thresholds, especially the bone conduction thresholds, were no different from those of the 11 BAHA users. However, in free field audiometry, the users gained superior benefit from their BAHA compared to their air conduction aid, whereas the nonusers did not. In conclusion, in all series to date, previous users of a conventional bone conduction aid have been delighted users of a BAHA and have gained superior audiometric benefit. This is not necessarily the case with previous air conduction aid users.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Candidature for hearing aids: justification for the concept and a two-part audiometric criterion.

A definition of hearing aid candidature is required for planning and other purposes. The number of candidates in the population actually receiving an adequate fitting would provide the major index of whether audiology services achieve their major public health goal. Many diverse factors determine the benefit that an individual receives from a hearing aid, and hence could in principle be included in some composite criterion for appropriate candidature reflecting the cost-effectiveness of patterns of provision. However, the complexity of universal capture, on those fitted with hearing aids, of data giving full auditory and demographic characteristics is beyond current routine NHS information systems. The most powerful known determinant established to date both of auditory disability and benefit is average hearing threshold level (HTL). Hearing threshold levels are hence both a necessary part of the fitting process and, given the data from the National Study of Hearing, a sufficient basis for computing population prevalences of hearing characteristics and service uptake in the major demographic strata. We report epidemiological data on consultation about problems with ears or hearing and uptake of hearing aids, which lead us to recommend a two-part candidature criterion on hearing threshold levels (0.5-4.0 kHz average): EITHER (a) better ear HTL > or = 35 dB OR (b) (15 dB < or = better ear HTL < 35 dB) WHEN worse ear HTL > or = 45 dB. The asymmetric component (b) may appear contentious, but is directly supported both by the epidemiological data and by further clinical data on benefit measured as performance on speech-in-noise tests. The proposed criterion is not over-liberal in clinical or related technological terms, but against the high prevalence of impairments in the population, the current provision and uptake of hearing aids in the UK still appear modest (about 3.3% in the population, and just under one-third of those qualifying by our criterion). Whatever the means of providing hearing aids, authorities charged with meeting the needs of their populations require such statistical indicators to know whether service delivery is appropriately geared. They should not use such an indicator as a basis of entitlement, as there are certainly individuals outside the criterion who receive benefit from their hearing aids. Equally, technological progress could expand the boundaries of candidature.

Adolescent↗