Formant Frequency-based Speech Enhancement Technique to improve Intelligibility for hearing aid users with smartphone as an assistive device.

In this paper, we present a Speech Enhancement (SE) method implemented on a smartphone, and this arrangement functions as an assistive device to hearing aids (HA). Many benchmark single channel SE algorithms implemented on HAs provide considerable improvement in speech quality, while speech intelligibility improvement still remains a prime challenge. The proposed SE method based on Log spectral amplitude estimator improves speech intelligibility in the noisy real world acoustic environment using the priori information of formant frequency locations. The formant frequency information avails us to control the amount of speech distortion in these frequency bands, thereby controlling speech distortion. We introduce a 'scaling' parameter for the SE gain function, which controls the gains over the non-formant frequency band, allowing the HA users to customize the playback speech using a smartphone application to their listening preference. Objective intelligibility measures show the effectiveness of the proposed SE method. Subjective results reflect the suitability of the developed Speech Enhancement application in real-world noisy conditions at SNR levels of -5 dB, 0 dB and 5 dB.