Microphone position estimation for acoustic impedance measurements

Authors
Peskens, Mallory
ORCID
Loading...
Thumbnail Image
Other Contributors
Xiang, Ning
Braasch, Jonas
Perry, Chris (Christopher S.)
Issue Date
2020-08
Keywords
Architectural sciences
Degree
MS
Terms of Use
This electronic version is a licensed copy owned by Rensselaer Polytechnic Institute, Troy, NY. Copyright of original work retained by author.
Full Citation
Abstract
The transfer functions of multiple microphones inside an impedance tube are widely used to derive the acoustic properties from experimental data, including normal incidence sound absorption/reflection and characteristic impedance of porous media. It is well known, that the measurement results from the normal incidence tube techniques are highly sensitive to precise microphone phase-matches and accurate microphone positions. Knowledge of the equivalent acoustic center of the microphones is required to obtain an accurate normal incidence measurement inside the tube. This paper discusses accurate and deliberate processes to locate the equivalent acoustic center of the microphones. A model of the reflection coefficient for a hypothetical air layer inside the tube and in front of a rigid back is used with the model-based Bayesian parameter estimation, to infer equivalent microphone positions. One calibration measurement of the transfer function between microphones is conducted to infer the equivalent microphone positions in the impedance tube. The model-based Bayesian method will be able to provide accurate acoustic centers for each necessary microphone without an additional microphone position. This paper discusses in detail the formulation of Bayesian parameter estimation, the model used, and the experimental results on estimated mean microphone positions and their uncertainties.
Description
August 2020
School of Architecture
Department
School of Architecture
Publisher
Rensselaer Polytechnic Institute, Troy, NY
Relationships
Rensselaer Theses and Dissertations Online Collection
Access
Restricted to current Rensselaer faculty, staff and students. Access inquiries may be directed to the Rensselaer Libraries.