Dialogue enhancement of stereo sound

Studies show that many people have difficulties in understanding dialogue in movies when watching TV, especially hard-of-hearing listeners or in adverse listening environments. In order to overcome this problem, we propose an efficient methodology to enhance the speech component of a stereo signal. The method is designed with low computational complexity in mind, and consists of first extracting a center channel from the stereo signal. Novel methods for speech enhancement and voice activity detection are proposed which exploit the stereo information. A speech enhancement filter is estimated based on the relationship between the extracted center channel and all other channels. Subjective and objective evaluations show that this method can successfully enhance intelligibility of the dialogue without affecting the overall sound quality negatively.

1. Introduction

Recent studies show that many people, especially hearing-impaired listeners, have problems in understanding dialogues in TV sound [1], [2]. Although movie soundtracks are normally carefully mixed in order to achieve a good speech intelligibility, problems can still arise in suboptimal listening conditions. To overcome this problem, approaches were proposed which aim at providing the user a control mechanism which allows for improving speech intelligibility. A straightforward method is proposed in [2] for enhancing the dialogue in discrete 5.1 mixes. Based on the assumption that the relevant dialogue is mixed into the center channel, this approach attenuates all non-center channels. A similar approach is proposed in [3]. For high-quality content delivery channels, such discrete multi-channel signals are typically available. For everyday broadcasting and streaming (e. g. YouTube), however, content is typically only available in the form of a stereo downmix which lacks the discrete center channel. In this case, more sophisticated methods for dialogue enhancement are necessary.