Improving the reliability of speech audiometry

A necessary feature of good recorded speech material is that each list should be identical in respect of graded order of difficulty. Extensive validatory tests have been carried out upon 20 M.R.C. word lists re-recorded by a professional announcer. It can be shown that by various manipulative procedures appreciable improvements may be obtained in the confidence limits of the material. In addition studies have been carried out upon the relationship between Speech Detection Threshold (S.D.T.) Speech Reception Threshold (S.R.T.) and Hearing level (H.L.) in normal hearing subjects. The surprising finding is that both S.D.T. and S.R.T. appear to be relatively independent of H.L. An analysis has been made of the words comprising the material in respect of their ease of recognition and is presented as an appendix.     

Delayed feedback audiometry: reliability of repeated measures

The test-retest reliability of hearing thresholds at 1000 Hz measured by a delayed auditory feedback procedure was compared with the reliability of thresholds obtained with voluntary responses to the same signal in 10 adults with normal hearing sensitivity. Thresholds for each procedure were obtained three times on each of 5 different days. Although the delayed feedback procedure yielded estimates of threshold which averaged 4.6 dB greater than those estimated by voluntary responses (p less than 0.05), there was no evidence that experience over time resulted in a change for the poorer in the precision of the test.     

Clinical trial of BOBCAT: 1st report on the reliability and validity of computerized pure-tone audiometry

Computerized diagnostic audiometry is quickly emerging as a viable productivity tool in the audiology clinic. To date, there has been little reported on its reliability and validity with the hearing-impaired. The 'Battery of Basic Computerized Audiometric Tests' (BOBCAT) is a computer program which puts a wide variety of clinical hearing tests under computer control. The purpose of the present study was to ascertain the reliability and validity of BOBCAT in the measurement of hearing sensitivity. A field study was conducted in a group of 92 workers exposed to noise to measure air- and bone-conduction thresholds. Coefficients of reliability of 0.85 and higher were obtained between air and bone thresholds for both methods of testing; that is, manual and computer-controlled audiometry. The same measurement between manual and computerized air-conduction pure-tone thresholds gave values ranging from 0.93 to 0.98. A principal-components analysis documented content validity of computerized audiometry. These results are interpreted as clear evidence of both reliability and validity of the BOBCAT procedure, with one exception: 6.7% of all observations are showing air-conduction computerized thresholds of -10 dB at one or more frequencies, with no confirmation by manual audiometry. This is attributed to insufficient randomization of intervals between stimuli, a problem which should be taken care of by new versions of the software.     

Comparative speech audiometry studies with compact disk]

We compared the results of speech audiometry, performed with recorded tape and CD, respectively, in 21 subjects with bone conduction hearing loss, and in 27 subjects with sensorineural hearing loss. In all cases, speech audiometry was performed by using the German Freiburg speech test material, recorded in 1969 on the basis of the German DIN standard 45626. In subjects with an air-bone gap, the hearing loss for speech is 2.3 dB smaller if tested by use of CD, and the speech recognition is 10.5 points better, respectively. Smaller differences could be found in sensorineural HL: For CD, the hearing loss is 1.2 dB smaller, and the speech recognition score is raised by only 1 point. These differences are statistically not significant, and the calculation of hearing impairment and individual hearing handicap from the tables commonly used in Germany in medicolegal expert opinions must not be corrected, if records on CD are used basing on the recordings from 1969 according to DIN 45626. The handling of compact discs has many advantages in relation to the handling of tapes.     

High-frequency audiometry using precision earphones: reliability under laboratory and field conditions

New circumaural earphones were tested in the frequency range from 100 Hz to 20 kHz and compared to commonly used supra-aural earphones. The circumaural earphone HD 230 (Sennheiser) generates test stimuli at up to 20 kHz with almost constant sound pressure levels when its pos ed on an artificial ear. The reproducibility of hearing threshold mea ed with a new microprocessor-controlled Békésy audiometer using the ne was nearly as good as under free-field conditions. The practicabil diagnostic value of high-frequency audiometry have been demonstrated er field conditions. For this application, the good sound attenuation these earphones (30 dB above 1 kHz) are important. High-frequency he ds of healthy pupils and of pupils with a history of otitis media are kHz, the hearing threshold level difference between both groups reached 20 dB.     

A controlled study of the reliability of pure tone audiometry for the detection of gentamicin auditory toxicity

Hearing changes in patients treated with gentamicin have been prospectively investigated. A group of patients who had a similar spectrum of clinical conditions but did not receive gentamicin have been studied as a control group. The audiometric technique was first validated by recording audiograms from healthy volunteers, once in an anechoic chamber and twice in a ward. It was concluded that changes in threshold less than 20 db. should not be regarded as significant when measured in a ward. In the gentamicin-treated group an initial audiogram was not a reliable measure of the patients' normal hearing because of the influence of their clinical condition. Twenty-one of the control patients were elective admissions to hospital and had their hearing first tested when they were clinically well. There was a 24 per cent incidence of unexplained hearing abnormalities--similar to the incidence of hearing loss in the gentamicin-treated group at follow-up. It was concluded that aminoglycoside auditory toxicity should not be assessed retrospectively. The incidence of hearing changes in the control and gentamicin-treated groups were similar. Possible causes of hearing loss in surgical patients are discussed and recommendations are made for the conduct of future studies of drug-induced auditory toxicity.