A note on the use of self-recording audiometry with children

The distribution of hearing threshold levels in the general population aged 18-30 years

Hearing threshold levels at audiometric frequencies between 0.25 and 8 kHz were obtained by manual audiometry using 5-dB steps in adults aged 18-30 years, as part of a large random survey of hearing in the UK. After screening to ensure otological normality, including careful analysis of any noise exposure history, the median thresholds of the 241 screened subjects deviated from audiometric zero by an average of 4.3 dB over the frequencies from 0.5 to 4 kHz in the direction of poorer hearing. Even greater deviations were evident at 0.25, 6 and 8 kHz, consistent with the discrepancies between normal hearing threshold and ISO 389 standard reference zero that have been reported previously. Within the age band from 18 to 30 years, age did not influence hearing threshold levels. Socio-economic status defined by occupational group (manual or non-manual) had a significant effect at frequencies up to 2 kHz, with those in non-manual occupations having better hearing than those in manual occupations by an average of 2.4 dB, despite screening for middle-ear disease, noise exposure and other possibly confounding factors. In a screened sample, males had better hearing threshold levels than females, but this difference was sensitive to screening criteria. The unscreened sample had median hearing threshold levels that were at most 2 dB worse than the screened sample across the frequency range.

Clinical pure-tone versus three-interval forced-choice thresholds: effects of hearing level and age

Hearing threshold levels were measured at 2 kHz using both a standard clinical procedure and a three-interval forced-choice procedure. The 240 subjects (aged 50-75 years) embraced both normal hearing and symmetrical sensorineural hearing impairment. The sample was carefully constructed to dissociate hearing threshold level from age, by oversampling the young impaired and the older normally hearing. The forced-choice threshold was found to be generally acuter than the clinical threshold. This was related to increasing severity of hearing loss at 1.7 dB per 10 dB HL and to age at 1.6 dB HL per 10 years. Hearing threshold accounted for 12% of the variance in the discrepancy between the two types of threshold, while age accounted for only 4% due to the narrow range used. After control for these thresholds and age, there were also significant associations with a self-estimate of hearing ability and with the neuroticism score from a personality questionnaire. When interpreting epidemiological findings, particularly in longitudinal studies, the separation between sensory and cognitive factors in threshold measures needs to be considered. The obtained discrepancies as a function of hearing level and age were applied to a statistical model for population prevalences for hearing impairment. The results suggested that the choice of method could have material effects on overall prevalence estimates and on the magnitude of the apparent age effect.

Comparison of manual and computer-controlled self-recorded audiometric methods for serial monitoring of hearing

Manual and self-recorded audiograms obtained from 240 ears on two occasions 2-3 years apart were compared, with the objective of establishing the preferred method for serial monitoring of hearing thresholds. The self-recording method incorporates an objective scoring algorithm which is compared with subjective scoring carried out independently by two experienced audiology staff members. The objective scoring method agreed well with the subjective method but gives substantial advantages in terms of cost and freedom from scorer bias. The variability associated with manual audiometry was somewhat lower than that associated with self-recording audiometry when used for serial monitoring.

Hearing threshold measurement in Menière's disease

The hearing thresholds of 21 subjects with a typical history of Menière's disease on one side were determined four times by Békésy audiometry at fixed frequencies (250, 500, 1 000 and 2 000 Hz). The reliability of the hearing thresholds was calculated and no differences could be found between the Menière ear and the unaffected ear. A considerable increase in standard deviation of hearing thresholds could be noted if the middle ear pressure varied more than +/- 50 mm H2O between the tests. The results showed that with Békésy audiometry a 7-dB increase or decrease in hearing thresholds reflects a significant change in hearing in Menière's disease.

Comparison of the hearing threshold measured by manual pure-tone and by self-recording (Békésy) audiometry

The hearing threshold of 115 subjects aged 25--63 years and working on a shipyard were determined both by Békésy sweep audiometry and by conventional manual octave pure-tone audiometry at fixed audiometric frequencies. The attenuation rate was 2.5 dB s-1 with pulsed-tone presentation and the sweep time from 0.25 to 10 kHz was 400 s for the Békésy audiometer. Manual pure-tone audiometry was performed in 5-dB steps. The Békésy method gave the lowest values for the hearing thresholds. It has been possible to find a useful linear relation between pure-tone and Békésy hearing thresholds. With the help of a retest experiment, it has been established, that the standard deviations of hearing thresholds obtained under similar conditions in a pure-tone investigation are about twice as large as those obtained in a Békésy investigation.

Comparison of the hearing threshold measured by pure-tone audiometry and by Békésy sweep audiometry

The hearing thresholds of 115 subjects, workers in a shipyard, were determined both by Békésy sweep audiometry and by conventional individual pure-tone audiometry at fixed audiometric frequencies. The Békésy method gave the lowest values for the hearing thresholds. It has been possible to find a useful linear relation between pure-tone and Békésy hearing thresholds. With the help of a retest experiment it has been established that the standard deviations of hearing thresholds, obtained under similar conditions in a pure-tone investigation, are about twice as large as those obtained in a Békésy investigation.