Calibration of distributed sound acquisition systems using TOA measurements from a moving acoustic source

Abstract

We present a method for calibrating a distributed microphone array using time-of-arrival (TOA) measurements. The calibration encompasses localization and gain equalization of the microphones, which are both important in applications such as beamforming. The availability of accurate TOA measurements between the microphones and a set of spatially distributed acoustic events is pivotal to the calibration task. We propose to use a moving acoustic source emitting a calibration signal at known intervals. We then show that the TOAs and the observed signals can be used to estimate the gain differences between microphones in addition to the more established microphone localization. Finally, we provide experimental results with simulated and real measured data to demonstrate that our approach facilitates accurate TOA measurements and hence, accurate localization and gain equalization, even in reverberant and noisy conditions.

Clock-Offset and Microphone Gain Mismatch Invariant Beamforming

“…Typically, gain equalisation is done by active compensation of the microphone gain differences. To estimate these gain differences, many approaches use acoustic test signals in combination with either time difference of arrival [6] or direction of arrival estimation [7]. These approaches thus require additional processing and information like sensor positions or emission time of the calibration signal.…”

Loudspeaker and Listening Position Estimation Using Smart Speakers

“…Acoustic source and sensor geometry calibration has been a research topic for several decades. A lot of work has focused on creating a map for individual sensors and sources which were not necessarily synchronised (see, e.g., [3][4][5][6][7][8]). However, at least four sources, four sensors, and a total of at least ten transducers (sources + sensors) are required to solve the geometry calibration in the synchronised case [4], and many current audio reproduction systems consist of fewer sources and sensors than that.…”

On near-field beamforming with smartphone-based ad-hoc microphone arrays

“…However, with the rapidly rising use of smartphones and other mobile devices, the idea of constructing ad-hoc microphone arrays based on such devices has become increasingly more attractive [3][4][5]. The main focus in ad-hoc microphone array research has been on the localization of the microphones and the synchronization of the clocks [3][4][5][6][7][8][9]. Indeed, localization and clock synchronization are important issues for algorithms such as beamforming.…”