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Influence of in situ , sound-level calibration on distortion-product otoacoustic emission variability
Standing waves can cause errors during in-the-ear calibration of sound pressure level (SPL), affecting both stimulus magnitude and distortion-product otoacoustic emission (DPOAE) level. Sound intensity level (SIL) and forward pressure level (FPL) are two measurements theoretically unaffected by stan...
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Published in: | The Journal of the Acoustical Society of America 2008-07, Vol.124 (1), p.288-300 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Standing waves can cause errors during in-the-ear calibration of sound pressure level (SPL), affecting both stimulus magnitude and distortion-product otoacoustic emission (DPOAE) level. Sound intensity level (SIL) and forward pressure level (FPL) are two measurements theoretically unaffected by standing waves. SPL, SIL, and FPL
in situ
calibrations were compared by determining sensitivity of DPOAE level to probe-insertion depth (deep and "shallow") for a range of stimulus frequencies
(
1
-
8
kHz
)
and levels
(
20
-
60
dB
)
. Probe-insertion depth was manipulated with the intent to shift the frequencies with standing-wave minima at the emission probe, introducing variability during SPL calibration. The absolute difference in DPOAE level between insertions was evaluated after correcting for an incidental change caused by the effect of ear-canal impedance on the emission traveling from the cochlea. A three-way analysis of variance found significant main effects for stimulus level, stimulus frequency, and calibration method, as well as significant interactions involving calibration method. All calibration methods exhibited changes in DPOAE level due to the insertion depth, especially above
4
kHz
. However, SPL demonstrated the greatest changes across all stimulus levels for frequencies above
2
kHz
, suggesting that SIL and FPL provide more consistent measurements of DPOAEs for frequencies susceptible to standing-wave calibration errors. |
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ISSN: | 0001-4966 1520-8524 |
DOI: | 10.1121/1.2931953 |