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Abstract
Objective: Single-channel noise reduction (SCNR) and dynamic range compression (DRC) are important elements in hearing aids. Only relatively few studies have addressed interaction effects and typically used real hearing aids with limited knowledge about the integrated algorithms. Here the potential benefit of different combinations and integration of SCNR and DRC was systematically assessed. Design: Ten different systems combining SCNR and DRC were implemented, including five serial arrangements, a parallel and two multiplicative approaches. In an instrumental evaluation, signal-to-noise ratio (SNR) improvement and spectral contrast enhancement (SCE) were assessed. Quality ratings at 0 and +6 dB SNR, and speech reception thresholds (SRTs) in noise were measured using stationary and babble noise. Study sample: Thirteen young normal-hearing (NH) listeners and 12 hearing-impaired (HI) listeners participated. Results: In line with an increased segmental SNR and spectral contrast compared to a serial concatenation, the parallel approach significantly reduced the perceived noise annoyance for both subject groups. The proposed multiplicative approaches could partly counteract increased speech distortions introduced by DRC and achieved the best overall quality for the HI listeners. Conclusions: For high SNRs well above the individual SRT, the specific combination of SCNR and DRC is perceptually relevant and the integrative approaches were preferred.
Acknowledgment
The authors thank their colleagues from the Oldenburg House of Hearing for support with the subject recruitment.
Declaration of interest
This work was supported by a grant of the German Ministry of Education and Research (BMBF), under project 13EZ1127D (“Model-based Hearing Aids”) and by the DFG Cluster of Excellence EXC 1077/1 “Hearing4all”.