Measurement of resonance frequency and loss factor of a microphone diaphragm using a laser vibrometer

Jae Gap Suh, Hack Yoon Kim, Yoiti Suzuki

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

The pressure sensitivity of a laboratory standard microphone is determined using a reciprocity technique that measures the electrical transfer impedance of two microphones connected acoustically by a coupler. The electrical transfer impedance is a function of the coupler volume and the equivalent volumes of the microphones. The equivalent volume given as a function of the frequency can be determined in experiments or can be calculated if the equivalent volume at a low frequency as well as the resonance frequency and loss factor of the microphone diaphragm are known. Therefore, it is necessary to determine the resonance frequency and the loss factor accurately to obtain an accurate reading of the pressure sensitivity. In this paper, a new method to determine the resonance frequency and loss factor of a microphone diaphragm is proposed. The frequency response of the diaphragm displacement is measured by a laser vibrometer and the part of the response near the resonance frequency is used to determine the microphone parameters via least square fitting with the equation of a vibration model with one degree-of-freedom. Since the values measured by this method are close to the nominal values and the repeatability is highly feasible, the proposed method will be useful to determine the resonance frequency and loss factor of a microphone diaphragm.

Original languageEnglish
Pages (from-to)258-261
Number of pages4
JournalApplied Acoustics
Volume71
Issue number3
DOIs
Publication statusPublished - 2010 Jan 1

Keywords

  • Laser vibrometer
  • Least square fitting
  • Loss factor
  • Microphone diaphragm
  • Resonance frequency

ASJC Scopus subject areas

  • Acoustics and Ultrasonics

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