Comparison of post-filtering methods for intelligibility enhancement of telephone speech

Post-filtering can be used to enhance the quality and intelligibility of speech in mobile phones. This paper introduces two straightforward post-filtering methods for near-end speech enhancement in difficult noise conditions. Both of the algorithms use a perceptually motivated high-pass filter to transfer energy from the first formant to higher frequencies. A Speech Reception Threshold (SRT) test was conducted to determine the performance of the proposed methods in comparison to a similar post-filtering approach and unprocessed speech. The results of the listening tests indicate that all of the post-filtering methods provide intelligibility enhancement compared to unprocessed speech, but there were no significant differences between the methods themselves.