Acoustic Noise and Echo Cancelling - Microphone Array Methods and Applications

Document type: Licentiates
Author(s): Mattias Dahl
Title: Acoustic Noise and Echo Cancelling - Microphone Array Methods and Applications
Series: Research report
Year: 1997
Pagination: 105
ISSN: 1103-1581
Publisher: University of Karlskrona/Ronneby - Lund University
City: Lund/Karlskrona
Organization: Blekinge Institute of Technology
Department: Dept. of Signal Processing (Institutionen för signalbehandling)
Dept. of Signal Processing S-372 25 Ronneby
+46 455 780 00
Authors e-mail:
Language: English
Abstract: This Licentiate thesis is divided into three parts corresponding to three different papers. There is one research report, one conference paper and one submitted
journal paper. All three parts deal with acoustic echo and/or noise cancelling problems when using adaptive microphone arrays. In particular, the papers address the
performance of an adaptive microphone array in a small enclosure such as the car cabin. A calibrating scheme is proposed which is independent of array geometry
and channel matching, and which calibrates the adaptive array to the given acoustic environment and to the given electronic equipment. Results from real
measurements in a car interior are included and compared with an analytical description of an adaptive microphone array.

Part A gives an analytical description of an adaptive microphone array which facilitates a simple built-in calibration to the environment and instrumentation.

Part B describes the method for performing acoustic echo cancelling with a dig-ital "on-site", "self-calibrating" microphone array system. The calibration process is a
simple indirect calibration which continuously adapts to the actual environment and electronic equipment. There is a US patent based on this part and an international
patent is currently under examination.

Part C presents a neural network based microphone array system, which is capable to continuously perform speech enhancement and adaptation to nonuniform
quantization, such as A-law and µ-law.
Subject: Signal Processing\Beamforming
Signal Processing\Speech Enhancement
Note: Also published as Research Report 97-2. ISRN: HKR-RES-97/2-SE. To view this document in fulltext go to Research Report 97-2
URN: urn:nbn:se:bth-00074