Comparison of fluctuating maskers for speech recognition tests.

OBJECTIVE

To investigate the extent to which temporal gaps, temporal fine structure, and comprehensibility of the masker affect masking strength in speech recognition experiments.

DESIGN

Seven different masker types with Dutch speech materials were evaluated. Amongst these maskers were the ICRA-5 fluctuating noise, the international speech test signal (ISTS), and competing talkers in Dutch and Swedish.

STUDY SAMPLE

Normal-hearing and hearing-impaired subjects.

RESULTS

The normal-hearing subjects benefited from both temporal gaps and temporal fine structure in the fluctuating maskers. When the competing talker was comprehensible, performance decreased. The ISTS masker appeared to cause a large informational masking component. The stationary maskers yielded the steepest slopes of the psychometric function, followed by the modulated noises, followed by the competing talkers. Although the hearing-impaired group was heterogeneous, their data showed similar tendencies, but sometimes to a lesser extent, depending on individuals' hearing impairment.

CONCLUSIONS

If measurement time is of primary concern non-modulated maskers are advised. If it is useful to assess release of masking by the use of temporal gaps, a fluctuating noise is advised. If perception of temporal fine structure is being investigated, a foreign-language competing talker is advised.