Measurement of Eardrum Acoustic Impedance

Allen, Jont B.

doi:10.1007/978-3-642-50038-1_6

Cited by 109 publications

(102 citation statements)

References 4 publications

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“…The decreases in magnitude of umbo motion relative to normal values at higher frequencies suggested an increase in the magnitude of the ear's impedance; however, how an interruption could produce an increase in middle-ear impedance was not clear. Some studies in animals have demonstrated narrow-band increases in middle-ear impedance resulting from ossicular interruption (25)(26)(27)(28)(29). Some of these studies have described this increase as an increase in the mass of the ear (25,26), whereas another has explained the decreased velocity magnitude and decrease in phase as a change in the spatial patterns of tympanic membrane motion (29).…”

Section: Summary Of Results and Comparison With Other Reportsmentioning

confidence: 99%

Diagnostic Utility of Laser-Doppler Vibrometry in Conductive Hearing Loss with Normal Tympanic Membrane

Rosowski¹,

Mehta²,

Merchant³

2003

Otology & Neurotology

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Hypothesis-It was hypothesized that laser-Doppler vibrometry measurements of umbo velocity in aerated middle ears with conductive loss can differentiate ossicular interruptions, stapes fixations, and mallear fixations. More generally, we hypothesize that laser-Doppler vibrometry measurements of umbo velocity can give information about how differences in the impedance that the ossicles work against affect middle-ear function.Background-Laser-Doppler vibrometry is a well-established research tool for exploring middle-ear function. The authors wished to investigate its potential as a clinical tool for differential diagnosis of the cause of conductive hearing loss.

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Section: Summary Of Results and Comparison With Other Reportsmentioning

confidence: 99%

Diagnostic Utility of Laser-Doppler Vibrometry in Conductive Hearing Loss with Normal Tympanic Membrane

Rosowski¹,

Mehta²,

Merchant³

2003

Otology & Neurotology

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“…Thévenin-equivalent characteristics of the ER-10Bþ probe assembly were determined (Møeller, 1960;Rabinowitz, 1981;Allen, 1986;Keefe et al, 1992) using four known acoustic loads (8.0-mm i.d. ; 30 -, 40 -, 50 -, and 70-mm lengths).…”

Section: Source Calibrationmentioning

confidence: 99%

Further assessment of forward pressure level for in situ calibration

Scheperle

Goodman

Neely

2011

The Journal of the Acoustical Society of America

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Quantifying ear-canal sound level in forward pressure has been suggested as a more accurate and practical alternative to sound pressure level (SPL) calibrations used in clinical settings. The mathematical isolation of forward (and reverse) pressure requires defining the Thévenin-equivalent impedance and pressure of the sound source and characteristic impedance of the load; however, the extent to which inaccuracies in characterizing the source and/or load impact forward pressure level (FPL) calibrations has not been specifically evaluated. This study examined how commercially available probe tips and estimates of characteristic impedance impact the calculation of forward and reverse pressure in a number of test cavities with dimensions chosen to reflect human ear-canal dimensions. Results demonstrate that FPL calibration, which has already been shown to be more accurate than in situ SPL calibration, can be improved particularly around standing-wave null frequencies by refining estimates of characteristic impedance. Better estimates allow FPL to be accurately calculated at least through 10 kHz using a variety of probe tips in test cavities of different sizes, suggesting that FPL calibration can be performed in ear canals of all sizes. Additionally, FPL calibration appears a reasonable option when quantifying the levels of extended high-frequency (10-18 kHz) stimuli.

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“…Input to the ME can then be quantified as the pressure incident on the TM, devoid of any standing-wave cancellations. This decomposition of total pressure is achieved by prior determination of the Thevenin-equivalent source impedance and pressure of the transducer ͑Sivian and White, 1933;Rabinowitz, 1981;Allen, 1986;Keefe et al, 1992;Neely and Gorga, 1998;Hudde et al, 1999;Farmer-Fedor and Rabbitt, 2002͒. Knowing the source impedance ͑Z s ͒ and pressure ͑P s ͒, the impedance of any unknown load ͑Z L ͒, whether the ear canal or another cavity, is defined as…”

Section: Introductionmentioning

confidence: 99%

Comparison of in-situ calibration methods for quantifying input to the middle ear

Lewis

McCreery

Neely

et al. 2009

The Journal of the Acoustical Society of America

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Sound pressure level in-situ measurements are sensitive to standing-wave pressure minima and have the potential to result in over-amplification with risk to residual hearing in hearing-aid fittings. Forward pressure level ͑FPL͒ quantifies the pressure traveling toward the tympanic membrane and may be a potential solution as it is insensitive to ear-canal pressure minima. Derivation of FPL is dependent on a Thevenin-equivalent source calibration technique yielding source pressure and impedance. This technique is found to accurately decompose cavity pressure into incident and reflected components in both a hard-walled test cavity and in the human ear canal through the derivation of a second sound-level measure termed integrated pressure level ͑IPL͒. IPL is quantified by the sum of incident and reflected pressure amplitudes. FPL and IPL were both investigated as measures of sound-level entering the middle ear. FPL may be a better measure of middle-ear input because IPL is more dependent on middle-ear reflectance and ear-canal conductance. The use of FPL in hearing-aid applications is expected to provide an accurate means of quantifying high-frequency amplification.

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Measurement of Eardrum Acoustic Impedance

Cited by 109 publications

References 4 publications

Diagnostic Utility of Laser-Doppler Vibrometry in Conductive Hearing Loss with Normal Tympanic Membrane

Diagnostic Utility of Laser-Doppler Vibrometry in Conductive Hearing Loss with Normal Tympanic Membrane

Further assessment of forward pressure level for in situ calibration

Comparison of in-situ calibration methods for quantifying input to the middle ear

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