Biomedical subjects

S Gatehouse

Publications and source records attributed to S Gatehouse.

At least 73 records · Page 4Linked to original sources

PubMed1988

Benefit from binaural hearing aids in individuals with a severe hearing impairment.

The relative benefits of binaural as opposed to monaural hearing aids were assessed by the use of a diotically presented, audiovisual speech-in-noise task in a group of bilateral, severely hearing-impaired individuals. Significantly greater benefit was gained from binaural amplification, irrespective of hearing level and degree of asymmetry. The benefit was considered to be due to central summation. It is concluded that binaural amplification should be attempted in all bilateral, severely hearing-impaired subjects. About 80% will accept this and be able to demonstrate benefit in an audiovisual task.

Adult↗

PubMed1987

The effects of air-bone gap and presentation level on word identification.

A sensorineural hearing loss is usually considered more disabling than a conductive loss of equivalent air conduction hearing level, due to the associated impairments in resolution which amplification does not overcome. In noise this generalization holds; however, in quiet, the generalization holds only for high intensity levels of presentation. Determination of isoperformance curves for word identification shows that at low stimulus levels the patient with conductive hearing loss suffers the greater disability for a given hearing loss. The crossover point between these regions, (i.e., where a single predictor from hearing level correctly predicts equal disability for conductives and sensorineurals) is in the region of 85 dB SPL--a level which approximates typical raised voice levels used when communicating under difficult circumstances. Given the long-standing distinction between conductive and sensorineural pathology, prediction of disability from dB HL as a general clinical substitute for actual disability measurement has rested upon a fortunate coincidence.

Acoustic Stimulation↗

PubMed1987

Optimum side for fitting a monaural hearing aid. 3. Preference and benefit.

Benefit from a simulated monaural hearing aid was assessed in diotic and dichotic listening conditions in 92 subjects with bilateral, mild to moderate sensorineural hearing impairment. In diotic conditions, subjects scored better on a speech identification task with an 'aid' in their better hearing ear. However, in dichotic conditions, a 'hearing aid' the better hearing ear was of no benefit when the signal came from the side of the poorer ear, while a 'hearing aid' in the poorer ear was of benefit in all listening situations. These results support the hypothesis that patients' preference for using an aid in their poorer hearing ear (Swan et al., 1987) is based on the desire to minimise their disability in the most disadvantageous listening situations.

Aged↗

PubMed1987

Optimum side for fitting a monaural hearing aid. 1. Patients' preference.

The criteria generally used to decide in which ear to fit a monaural hearing aid are based on theory or anecdote and have not been verified by experimental observation. In this study to determine optimum side of fitting, 58 new hearing aid users were fitted with a hearing aid in one ear for 10 weeks, and then fitted in the other ear for a further 10 weeks. Subsequently, the subjects were asked their preference for side of hearing aid use and their reasons for this preference. 30 (52%) subjects reported better hearing with their aid in one ear than in the other; 24 (80%) of these preferred the ear with the poorer half-peak level elevation on a speech audiogram. The remaining 28 (48%) reported no difference in their aided hearing ability between ears, though 20 preferred one ear for practical reasons, unrelated to audiometric parameters. A patient's preference for side of fitting can be predicted from audiometric data but with only modest reliability. It is, therefore, recommended that bilateral ear moulds should be routinely provided for bilateral mild to moderate hearing impairment (speech frequency average less than 75 dB HL). If it is decided that only one ear mould should be provided, this should be made for the poorer hearing ear. The poorer hearing ear is best identified from the half-peak level elevation on a speech audiogram.

Adult↗

PubMed1987

Optimum side for fitting a monaural hearing aid. 2. Measured benefit.

The benefit obtained from wearing a hearing aid in either ear was assessed in 52 subjects using an audiovisual test. The sound source was located directly in front of the subject. Overall the subjects obtained more benefit with their aid in their better hearing ear, despite having expressed a preference for using the aid in their poorer hearing ear. Seven of the subjects who had asymmetrical hearing were tested further using an auditory test with the sound source either in front of the subject or to either side. The results suggest that the subjects' preference for the poorer hearing ear are based on a desire to minimise their disability in the most disadvantageous listening situations.

Functional Laterality↗

PubMed1986

Blood viscosity as a factor in sensorineural hearing impairment.

The cause of sensorineural hearing impairment is unknown in a high proportion of patients. Since ischaemia is a possible factor, the relation between hearing threshold and blood viscosity, plasma viscosity, and haematocrit was investigated in 49 patients with idiopathic hearing loss, taking into account age, sex, smoking, and socioeconomic group. Hearing thresholds were unrelated to haematocrit or low-shear blood viscosity. Hearing impairment at high frequencies was directly related to high-shear blood viscosity and inversely related to plasma viscosity. The derived measure of red-cell rigidity was significantly related at all frequencies to hearing thresholds. A second study of 92 subjects from a population sample confirmed the inverse relation with plasma viscosity and lack of relation with haematocrit. Increased pure-tone thresholds appear to be related to increased red-cell rigidity; this may be an important factor in sensorineural hearing impairment with implications for diagnosis and prevention.

Adult↗

PubMed1986

A cross-over study of side of hearing aid provision.

No previous study has investigated which ear should be fitted with a hearing aid. Fifty-eight patients with bilateral hearing loss of 25-75 dB HL were sequentially fitted with an ear level hearing aid for 10 weeks in each ear. Patients were then asked their preference for side of fitting, and their reasons for this preference. Thirty-five patients had symmetrical hearing: 17 (49%) preferred one ear because they could hear better with the aid in that ear, and 12 (34%) chose one side for practical reasons. Twenty-three patients had asymmetrical hearing: 8 (35%) preferred one side for practical reasons, and 13 (57%) could hear better with the aid in one ear, which was invariably the poorer hearing ear. As the preferred ear cannot be reliably predicted, bilateral ear moulds should be provided. If only one mould is provided, it should be for the poorer hearing ear.

Adult↗

PubMed1986

A micro-computer based trainer for pure-tone audiometry.

A micro-computer based system to simulate patient performance on pure-tone audiometry has been developed, which in conjunction with a dummy audiometer allows easy development of a student training facility. The system can be easily configured to realistically and comprehensively represent a wide range of hearing losses. Students can then acquire the necessary technical skills to produce accurate pure-tone threshold determinations free from the restraints of a clinical setting.

Audiometry↗

PubMed1986

A scale for hearing aid benefit measures and auditory disability.

Quoting disability scores or measures of hearing aid benefit based on percent correct word identification or on dB signal-to-noise ratio at criterion performance poses a communication problem as scientists and clinicians may have no intuitive understanding of the scales involved. In particular, percent correct does not allow direct comparison of differences obtained at different performance levels, for example by different subject groups. In circumstances where the better ear hearing levels are known to be a major determinant of disability, it is both possible and legitimate to transform performance measures such as percent correct into a dB HL equivalent. In two sets of data from clinical research projects this relationship is shown to be linear, allowing a particularly simple transformation and giving an already understood scale. This transformation procedure has been cross-validated against the acoustic gain used in a sample of patients with conductive losses where the hearing loss is purely an attenuation. The procedure is offered as a metric for expressing the benefits of management.

Correction of Hearing Impairment↗

PubMed1985

The doubtful value of tympanometry in the diagnosis of otosclerosis.

Many consider that the compliance of the middle ear as measured from the tympanogram can be helpful in diagnosing otosclerosis. To test this assertion, the compliance in 34 individuals with surgically proven otosclerosis was compared with the compliance in 34 age and sex matched, normal controls, randomly selected from the population. Though the mean compliance was different in the two groups, there was considerable overlap in the range of values which severely limits the practical usefulness of tympanometry. If the level of compliance is taken at which a false negative diagnosis would be made in 10 per cent of otosclerotic ears, a false positive diagnosis of otosclerosis would be made in 88 per cent of normal ears. If the level of compliance is taken at which a false positive diagnosis of otosclerosis would be made in 10 per cent of normal ears, 72 per cent of ears with otosclerosis would be considered normal. It is concluded that tympanometry will not help to arrive at a diagnosis of otosclerosis.

Acoustic Impedance Tests↗

PubMed1984

Hearing in acromegaly.

Fifty-six individuals with acromegaly referred for pituitary surgery were studied to determine any relationship between acromegaly and sensorineural or conductive hearing loss. Compared to a matched population control sample, no significant difference between the acromegalics and controls has been found, either for air conduction or for bone conduction. The differences between these findings and those published previously are discussed, and reasons proposed to explain the discrepancies.

Acromegaly↗

PubMed1984

Acoustical characteristics of surgically altered human temporal bones.

The resonance qualities of the external auditory canal can increase the sound pressure level (SPL) at the tympanic membrane by as much as 20 dB between 2 and 4 kHz. Surgery on the canal, particularly in the form of a modified radical mastoidectomy, might be expected to affect this with resultant implications for speech discrimination. The creation of a modified radical mastoidectomy in 6 temporal bones altered the SPL at the tympanic membrane by +10 dB at 2 kHz, +14 dB at 2.5 kHz, -2 dB at 3 kHz, -12 dB at 3.5 kHz, -20 dB at 4 kHz, -16 dB at 5 kHz and -8 dB at 6 kHz. When this transfer function was applied to 2 subjects, speech discrimination in noise was reduced by 6%. Whether this is of any magnitude compared with the effect of the disease requires prospective studies in individuals undergoing a modified radical mastoidectomy.

Acoustics↗

PubMed1982

Hearing loss in minor head injury.

A prospective otological and audiological study was made of 130 consecutive persons with head injuries. A comparison was made with 87 consecutive persons with traumatic injuries but without head injuries. Five (4%) of the persons with head injuries had an unsuspected temporal bone fracture evident on otoscopy but not on routine skull roentgenography. These persons had a significant sensorineural hearing loss at 4 and 8 kHz compared with other patients with head injuries. Routine otoscopic examination is considered advisable in all persons with head injuries. No significant difference in the hearing was detected in persons with head injuries without a temporal bone fracture compared with control subjects.

Adolescent↗

PubMed1982

A re-examination of the Carhart effect.

It is well established that in individuals with a conductive hearing loss the bone conduction thresholds do not directly indicate cochlear function, and are artificially depressed as witnessed by their improvement following successful reconstructive surgery. This depression, which we define as the 'Carhart effect' is due to changes in the middle and external ear contributions to bone conduction. Published figures for the Carhart effect, inferred from pre- and post-operative bone conduction thresholds vary considerably but the discrepancies are markedly reduced when the appropriate selection criteria are used. However, theoretical considerations would suggest that values based on a comparison of bone conduction before and after surgery underestimate the size of the Carhart effect. This is confirmed at least at low frequencies, by a series of experiments on six normal individuals in whom an artificial conductive hearing loss was created by increasing the ear canal pressure. The change in bone conduction threshold was 5 dB at 250 Hz, and 15 dB at 500 Hz, changes greater than those estimated from surgical data.

Auditory Threshold↗

PubMed1981