Modulation masking release using the Brazilian-Portuguese HINT: Psychometric functions and the effect of speech time compression

Abstract

Objective: The Brazilian-Portuguese hearing in noise test (HINT) was used to investigate the benefit to speech recognition of listening in a fluctuating background. The goal was to determine whether modulation masking release varied as a function of the speech-to-masker ratio at threshold. Speech-to-masker ratio at threshold was manipulated using the novel approach of adjusting the time-compression of the speech. Design: Experiment 1 measured performance-intensity functions in both a steady speech-shaped noise masker and a 10-Hz square-wave modulated masker. Experiment 2 measured speech-to-masker ratios at threshold as a function of time-compression of the speech (0, 33, and 50%) in both maskers. Study sample: Participants were normal-hearing adults who were native speakers of Brazilian Portuguese (Experiment 1: N = 10; Experiment 2: N = 30). Results: The slope of the performance-intensity function was shallower in the modulated masker than in the steady masker for both words and sentences. Thresholds increased with increasing time-compression in both maskers, but more markedly in the modulated masker, resulting in reduced modulation masking release with increasing time-compression. Conclusions: Speech-to-masker ratio at threshold varies with time-compression of speech. The results are relevant to the issue of whether degree of masker modulation benefit depends on speech-to-masker ratio at threshold.

Key Words::

• Modulation masking release
• speech recognition
• time compression
• psychometric function

Note

Acknowledgements

We thank Emily Buss for helpful discussions on the topic of psychometric functions. We are also grateful to two reviewers for their insightful comments on an earlier version of this manuscript.

Declaration of interest: The authors report no conflicts of interest.

This work was supported by grants R03DC012278 and R01DC001507 from the NIH NIDCD.

Notes

1. A similar outcome is found if this exercise is repeated with thresholds in the modulated masker used as reference.