Comparison of post-processing methods for intelligibility enhancement of narrowband speech in a mobile phone framework

Post-processing methods can be used in mobile communications to improve the intelligibility of speech in adverse background noise conditions. This study addresses the improved intelligibility and the speech quality achieved with a well-known approach, dynamic range compression, by comparing it to two other real-time postprocessing methods based on energy reallocation. In addition, the effects of utilizing amplitude normalization instead of energy normalization on the performance of the post-processing methods are investigated. The evaluations were conducted using subjective tests in several background noise conditions. The results indicate that the two energy reallocating approaches outperform dynamic range compression both in intelligibility and quality and that amplitude normalization causes the performance of the tested post-processing methods to degrade in some conditions.