Dereverberation of speech signals is becoming more important to speech enhancement with the increase in hands-free communications systems. Speech reverberation can be a significant problem especially in free-space systems, such as videoconferencing, laptops, and tablets where environmental echoes can be disruptive to conversations. With these systems, it is not the responsibility of the user to move closer to the microphone, but the responsibility of engineers to develop speech enhancement systems that provide users the freedom they desire in these environments.
The concept for dereverberation of speech is similar to that of acoustic echo cancellation. Speech dereverberation attempts to model the transfer function of the acoustic environment (room impulse response) and filter it from the received microphone signal. However, in this case the problem is more complex because we do not have access to the original sound source. A sound source located a distance from a microphone will have its direct path signal arrive at the microphone and then reflections of the original signal will be captured. If the sound source is located close to the microphone then the signal to reverberation ratio will be low, but as the distance from the source to the microphone increases the effect of reverberation.
For more information:
- Estimation of Room Impulse Response
- Dereverberation using Spectral Subtraction
- Voice Activity Detection for Dereverberation of Speech
- Reverberation Cancellation versus Suppression
- Combination of dereverberation and adaptive beamforming
- Variable Tap Length Filters for Acoustic Echo Cancellation
- Octave Banks for Acoustic Filtering