Audio Playback: Perceptual optimization of sound presentation over spatially distributed loudspeakers

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This project addresses the general challenge of this Research Unit to develop methods for an improved and individualized presentation of acoustic signals to listeners. In the second funding period we will address all three problems that the Research Unit focusses on, "sound presentation", "interfering noise", and "individualization".In this project we will focus on the sound presentation over loudspeakers. Here we will consider methods to adapt the input signals for loudspeakers such as to enhance the speech intelligibility when listening in a room with reverberation and interfering noise sources. In addition, we will consider methods to individually optimize the sound presentation taking into account measured acoustical properties of the room.In the second funding period we will extend the work on speech intelligibility that was started in the first funding period. A preprocessing method was developed that successfully enhanced the intelligibility of speech reproduced over loudspeakers affected by room-reverberation by minimizing the auditory masking of the dry speech signal by the room reverberation. In the next funding period, we will extend this work by also including the auditory masking effects of interfering noise such that we can also enhance speech intelligibility in a reverberant room with interfenng noise. In collaboration with TP E which is developing speech intelligibility prediction models we will find algorithms that optimize the spectral content and apply dynamics compression if required for an individual listener with hearing impairment.In the first funding period also the perceptually accurate reproduction of a recorded sound field in a specific playback room was investigated. As demonstrated in listening tests, we were able to adapt to the individual room acoustical properties of the playback room. In the second funding period we will extend this work in three manners. First it will be extended to be able to record and reproduce spatially distributed sound sources with a single recording unit that is placed at the listener's position in the recording room. Here a combination with an ambisonics reproduction system will be pursued. It will require to investigate how the ambisonics system excites the reverberant sound field in the playback room in order to be able to optimize the properties of the reverberant sound field.A second effort will be related to the fact that with the current optimization method both the recording and the playback room properties are taken into account. We want to investigate whether it is possible to make a single recording format that can be input to a playback system that only has knowledge about the playback room.A third effort will look at methods to use conventional stereo content (which is the current recording standard) as an input for the proposed reproduction method.