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Journal Article

An Added-Mass Measurement Technique for Transducer Parameter Estimation

Authors: Candy, Jeff; Futtrup, Claus

Journal of the Audio Engineering Society · Volume 65 · Issue 12 · pp. 1005–1016 · December 2017

Abstract

This report presents a methodology to measure transducers using a dual-added-mass technique in order to extract the motional impedance ZM(w) and force factor Bl from the total impedance. The method is more accurate than the classical single-added-mass approach insofar as the blocked electrical impedance can be completely filtered out of the total impedance. The methodology is suitable for determining moving mass and compliance in motional impedance models that include viscoelasticity and frequency-dependent damping. It is applicable to transducers for which adding mass to the moving parts is possible without introducing significant artifacts. A mass-consistency test is described to provide an internal validity check for the impedance fitting process. This test is quite stringent and provides an objective measure of the quality of the fit to the measured impedance. The quality of the proposed measurement technique was verified with an ANOVA Gage R&R measurement system analysis.

Details

Publication
Journal of the Audio Engineering Society
Volume
65
Issue
12
Pages
1005–1016
Publication date
December 6, 2017
Affiliation
Pietra, San Diego, CA, USA; SEAS Fabrikker AS, Norway (See document for exact affiliation information.)
Type
Journal Article