Publications – Details
Reverberation-Based Post-Processing for Improving Speech Intelligibility
- Authors:
- Magnus Schäfer, Marco Jeub, Bastian Sauert, and Peter Vary
- Book Title:
- International Congress on Acoustics (ICA)
- Venue:
- Sydney, Australia
- Event Date:
- 23.-27.8.2010
- Organization:
- Australian Acoustical Society
- Location:
- Sydney
- Date:
- Aug. 2010
- ISBN:
- 978-0-64654-052-8
- URL:
- http://www.acoustics.asn.au/conference_proceedings...
- Language:
- English
Abstract
When evaluating new algorithms for speech and audio coding or enhancement systems (e.g., noise reduction, echo control, or artificial bandwidth extension), one will usually listen to audio examples on headphones and not use any loudspeaker setup that might be available. The reasoning behind this choice is that using a headphone reproduction system makes it easier to identify even small signal processing artifacts which would be at least partly concealed by room reflections in listening rooms.
Usually, these artifacts due to coding or signal enhancement can not be completely removed but only minimized with respect to the constraints of the application. Examples could be a limited data rate for speech and audio coding or a trade-off decision between noise attenuation and speech distortion in noise reduction algorithms.
Based on the aforementioned superiority of headphones for making these artefacts noticeable, this contribution presents a postfilter that mimics the properties of listening rooms to conceal residual errors and artifacts. This postfilter is a finite impulse response filter that is designed according to measured or simulated room impulse responses.
The main focus of this contribution lies on the evaluation of different types of impulse responses for a reverberation-based postfiltering of speech signals that were transmitted by speech codecs at low data rates. In an exemplary study based on the Adaptive Multi-Rate WideBand (AMR-WB) speech codec, the proposed post-processing leads to an increase in the Speech Transmission Index (STI), which indicates a better intelligibility. Optimized impulse responses for the different data rates of (AMR-WB) are given in order to maximize the (STI).
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