Determining the area of the sweet spot in a surround loudspeaker setup for various microphone techniques

Abstract

Several types of microphone techniques exist to record music performances for surround‐sound reproduction. Variations between different techniques are found in the distance and angle between the microphones, and the choice of directivity patterns. All the arrays are targeted to produce an accurate spatial impression at the sweet spot. The aim of this investigation is to determine how different microphone techniques affect the size of the sweet spot, the area in which the spatial cues are reproduced with sufficient accuracy. In particular, the common belief that spaced techniques lead to larger sweet‐spot areas than coincidence and near‐coincident techniques is investigated. For this purpose, impulse responses (IR) of different microphone arrays are measured in a concert hall. Afterwards, test sounds are convolved with the measured IRs and presented through a surround loudspeaker setup in a control room. A dummy head is used to record the reproduced sound fields at different positions inside the listening area. In a psychoacoustic experiment, listeners are asked to rate the different recordings according to the spatial impression provided by different recording techniques. The results of the listening test will be presented and compared to signal analyzes of a binaural model.