Distribution of standing-wave errors in real-ear sound-level measurements

Susan A. Richmond, Judy G. Kopun, Stephen T. Neely, Hongyang Tan, Michael P. Gorga

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Standing waves can cause measurement errors when sound-pressure level (SPL) measurements are performed in a closed ear canal, e.g., during probe-microphone system calibration for distortion-product otoacoustic emission (DPOAE) testing. Alternative calibration methods, such as forward-pressure level (FPL), minimize the influence of standing waves by calculating the forward-going sound waves separate from the reflections that cause errors. Previous research compared test performance (Burke, 2010) and threshold prediction (Rogers, 2010) using SPL and multiple FPL calibration conditions, and surprisingly found no significant improvements when using FPL relative to SPL, except at 8 kHz. The present study examined the calibration data collected by Burke and Rogers from 155 human subjects in order to describe the frequency location and magnitude of standing-wave pressure minima to see if these errors might explain trends in test performance. Results indicate that while individual results varied widely, pressure variability was larger around 4 kHz and smaller at 8 kHz, consistent with the dimensions of the adult ear canal. The present data suggest that standing-wave errors are not responsible for the historically poor (8 kHz) or good (4 kHz) performance of DPOAE measures at specific test frequencies.

Original languageEnglish (US)
Pages (from-to)3134-3140
Number of pages7
JournalJournal of the Acoustical Society of America
Volume129
Issue number5
DOIs
StatePublished - May 2011

ASJC Scopus subject areas

  • Arts and Humanities (miscellaneous)
  • Acoustics and Ultrasonics

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