To assess whether different compact disk recording protocols, used to prepare speech test material, affect the reliability and comparability of speech audiometry testing.

We conducted acoustic analysis of compact disks used in clinical practice, to determine whether speech material had been recorded using similar procedures. To assess the impact of different recording procedures on speech test outcomes, normal hearing subjects were tested using differently prepared compact disks, and their psychometric curves compared.

Acoustic analysis revealed that speech material had been recorded using different protocols. The major difference was the gain between the levels at which the speech material and the calibration signal had been recorded. Although correct calibration of the audiometer was performed for each compact disk before testing, speech recognition thresholds and maximum intelligibility thresholds differed significantly between compact disks (p < 0.05), and were influenced by the gain between the recording level of the speech material and the calibration signal.

To ensure the reliability and comparability of speech test outcomes obtained using different compact disks, it is recommended to check for possible differences in the recording gains used to prepare the compact disks, and then to compensate for any differences before testing.

This study aimed to evaluate the predictive value of both hearing level (at various frequencies) and speech discrimination for forecasting hearing outcome after a period of observation, in patients with vestibular schwannoma.

Over a 33-year period, 1144 patients with vestibular schwannoma were allocated to ‘wait and scan’ management, with annual magnetic resonance imaging and audiological examination. Two complete pure tone and speech discrimination audiograms were available for 932 patients.

The predictive value of initial hearing level better than 10 dB for forecasting hearing outcome after observation increased from 59 per cent at 250 Hz to 94 percent at 4000 Hz. At diagnosis, hearing level of 10 dB or better at 4000 Hz was found in only 18 of the 932 VS ears, while good speech discrimination was found in 159 patients (17 per cent). Of the latter patients, 138 maintained good hearing after observation.

In vestibular schwannoma patients, good high frequency hearing and good speech discrimination at diagnosis are useful tools in predicting good hearing after observation.