Use of the California Consonant Test in evaluating hearing aids

The California Consonant Test (CCT) was used to evaluate different hearing aids for twelve listeners with mild to moderate sensorineural hearing losses. The CCT was mixed with white noise at signal-to-noise ratios (S/Ns) of +30 (quiet), +15, +5, and O dB and presented through hearing aids for each listener; the quiet condition was retested. Significant differences were found between mean test scores for the high and low S/Ns. Intralistener hearing aid differences were found most frequently in the quiet condition. Truncation errors were frequent for the low S/Ns. These findings indicate that the sensitivity of the CCT is decreased rather than increased by mixing it with noise. Critical differences of 5% or more between hearing aids were more frequent as the S/N improved; the greatest number of differences occurred for the quiet condition.