Between and within listener variability in response to CID W-22 presented in noise.

Two studies were conducted wherein college students with normal hearing sensitivity listened to CID W-22 recordings (Technisonics Studios) mixed with white noise. Four-word discrimination scores were obtained from each listener. In one study, a speech-to-noise ratio of approximately +1 dB was used whereas +7 dB was used in the other. Large standard deviations and low correlations indicate that the use of background noise with this clinical word discrimination test is associated with a relatively large amount of response variability and unreliability. These results suggest that the performance score obtained from a single list of CID W-22 presented in noise may not be a reliable indicator of a listener's true discrimination ability and therefore clinical interpretation of a listener's performance should be made with caution.

On the calibration of two commercially recorded versions of CID auditory test W-22.

Electroacoustic analysis of two commercially available versions of CID W-22 indicated significant differences in calibration. Measured differences in level between calibration tone and stimulus words were plus 5 to 8 dB for Technisonic recordings and plus one dB for Auditec recordings. As a consequence, the Technisonic Studios recordings were approximately 40% more intelligible than were Auditec recordings when presented to normal-hearing listeners in a background of competing speech spectrum noise in a condition where the level of the calibration tone of the respective recordings was used as the reference value to specify nominal speech-to-noise ratio.

Word discrimination in noise: effect of different speakers.

This study reports significant differences in listeners' performance when different speakers administer a test of speech intelligibility in noise in a manner that purportedly would yield equivalent test results. Six speakers, three female and three male, each recorded list 4 of the CID W-22 discrimination test. The recordings were mixed with speech noise at speech-to-noise ratios of +5, +1, and -3 dB. Three groups of 14 normal-hearing subjects were used. Each group heard the six speakers at one of the three speech-to-noise conditions. Equivalence between speakers was considered to have been achieved when means were not different and correlations were high. Results suggest that the assumption of interspeaker equivalence may not be valid when speech discrimination is measured in a background of noise.

Some suggestions on how to evaluate a transposer hearing aid.

The research presented here indicates that transposer hearing aids, which are now available commerically, might be helpful to some people. Specifically, it might help some people to detect the /s/, /integral/, /t/, /tintegral/, and possibly /k/ phonemes in speech. Any person considering the purchase of a transposer should be properly tested with one to determine whether the information provided by frequency transposition is helpful. It appears this evaluation cannot be done properly using procedures developed to evaluate a conventional hearing aid for a person with a mild or moderate communication impairment. Rather than outline a specific procedure, this report makes suggestions that a clinician might find useful when asked to evaluate the possible benefits of a transposer hearing aid for a client.