Parametric Time-Frequency Domain Spatial Audio

7 Multi-Channel Sound Acquisition Using a Multi-Wave Sound Field Model

Oliver Thiergart and Emanuël Habets

International Audio Laboratories Erlangen, a Joint Institution of the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) and Fraunhofer IIS, Erlangen, Germany

7.1 Introduction

During the last decade, different devices with two or more microphones have emerged that enable multi-channel sound acquisition. Typical examples include mobile phones, digital cameras, and smart television screens, which can be used for a huge variety of audio applications including hands-free communication, spatial sound recording, and speech-based human–machine interaction. Key to the realization of these applications with different devices is flexible and efficient sound acquisition and processing. “Flexible” means that the sound can be captured with different microphone configurations while being able to generate one or more desired output signals at the reproduction side depending on the application. “Efficient” means that only a few audio signals, in comparison to the number of microphones used, need to be transmitted to the reproduction side while maintaining full flexibility.

This flexible and efficient sound acquisition and processing can be achieved using a parametric description of the spatial sound. This approach is used, for example, in directional audio coding (DirAC) as discussed in Chapter 5 (Pulkki, 2007) or high angular resolution plane-wave expansion (HARPEX; Berge and Barrett, ...