High‐frequency plane waves in the ear canal: Application of a simple asymptotic theory

1988 ◽  
Vol 84 (6) ◽  
pp. 2070-2080 ◽  
Author(s):  
R. D. Rabbitt
Keyword(s):  
High Frequency ◽  
Asymptotic Theory ◽  
Plane Waves ◽  
Ear Canal

On the Use of Transfer Approaches to Predict the Vibroacoustic Response of Poroelastic Media

2016 ◽  
Vol 24 (02) ◽  
pp. 1550020 ◽  
Author(s):  
Q. Serra ◽  
M. N. Ichchou ◽  
J.-F. Deü
Keyword(s):  
Transfer Matrix ◽  
High Frequency ◽  
Plane Waves ◽  
Finite Size ◽  
Low Frequency ◽  
Acoustic Response ◽  
Frequency Range ◽  
Finite Size Effects ◽  
Poroelastic Media ◽  
Lateral Boundary Conditions

The transfer matrix method (TMM) is a famous analytic method in the vibroacoustic community. It is classically considered as a high frequency approach, because of the hypothesis of acoustic plane waves impinging on a flat infinite panel. Thus, it cannot take into account directly finite-size effects or lateral boundary conditions (BCs), and it needs specific algorithms to correct its results in the low frequency range. Within the transfer matrix framework, the use of finite elements makes it possible to generalize the range of applications of transfer approaches. Thus, the study of wave propagation in poroelastic media, in presence of lateral BCs can be carried out. The links between theses waves and the acoustic response of a sample are investigated. Finally, it shows that transfer approaches are not limited in the low frequency range, as usually stated. In fact, the validity of analytic transfer approaches depends more on the material and on the geometry than on the frequency range.

A Layered Notch Filter for High-Frequency Dynamic Isolation

1989 ◽  
Vol 111 (1) ◽  
pp. 17-24 ◽  
Author(s):  
J. L. Sackman ◽  
J. M. Kelly ◽  
A. E. Javid
Keyword(s):  
High Frequency ◽  
Plane Waves ◽  
Notch Filter ◽  
Theoretical Development ◽  
Parallel Plates ◽  
Layered Composites ◽  
Mechanical Filter ◽  
Specific Frequency ◽  
Working Principle ◽  
High Frequency Vibrations

An efficient method of isolation from high-frequency vibrations is the use of periodically layered composites acting as a mechanical filter. This device is a periodically layered stack of alternating materials with widely different densities and stiffnesses. The working principle of the device is wave reflection, and the device becomes increasingly effective when there is a large impedance mismatch which leads to rapid attenuation of an input wave for certain frequency ranges. This filter acts only in specific frequency bands. At other frequencies, it will transmit the vibratory energy unmodified, thus acting as a mechanical notch filter. The theoretical development of the mechanical notch filter is based on the theory of waves in periodically layered media. Floquet theory is used to solve the equations for the propagation of plane waves through a laminated system of parallel plates of different materials when the direction of propagation is normal to the plates. Several experiments were conducted to prove the validity of the mechanical notch filter concept. These experiments demonstrated that the theory is correct and that the results have practical application.

Evaluation of the Repeatability and Accuracy of the Wideband Real-Ear-to-Coupler Difference

2018 ◽  
Vol 29 (06) ◽  
pp. 520-532 ◽  
Author(s):  
Jonathan M. Vaisberg ◽  
Paula Folkeard ◽  
John Pumford ◽  
Philipp Narten ◽  
Susan Scollie
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Repeated Measures ◽  
Ear Canal ◽  
Repeated Measures Anova ◽  
Absolute Agreement ◽  
The Difference ◽  
Db Difference ◽  
Additional Clinical Benefit ◽  
Reported Data

AbstractThe real-ear-to-coupler difference (RECD) is an ANSI standardized method for estimating ear canal sound pressure level (SPL) thresholds and assisting in the prediction of real-ear aided responses. It measures the difference in dB between the SPL produced in the ear canal and the SPL produced in an HA-1 2-cc coupler by the same sound source. Recent evidence demonstrates that extended high-frequency bandwidth, beyond the hearing aid bandwidth typically measured, is capable of providing additional clinical benefit. The industry has, in turn, moved toward developing hearing aids and verification equipment capable of producing and measuring extended high-frequency audible output. As a result, a revised RECD procedure conducted using a smaller, 0.4-cc coupler, known as the wideband-RECD (wRECD), has been introduced to facilitate extended high-frequency coupler-based measurements up to 12.5 kHz.This study aimed to (1) compare test–retest repeatability between the RECD and wRECD and (2) measure absolute agreement between the RECD and wRECD when both are referenced to a common coupler.RECDs and wRECDs were measured bilaterally in adult ears by calculating the dB difference in SPL between the ear canal and coupler responses. Real-ear probe microphone measures were completed twice per ear per participant for both foam-tip and customized earmold couplings using the Audioscan Verifit 1 and Verifit 2 fitting systems, followed by measurements in the respective couplers.Twenty-one adults (mean age = 67 yr, range = 19–78) with typical aural anatomy (as determined by measures of impedance and otoscopy) participated in this study, leading to a sample size of 42 ears.Repeatability within RECD and wRECD was assessed for each coupling configuration using a repeated-measures analysis of variance (ANOVA) with test–retest and frequency as within-participants factors. Repeatability between the RECD and wRECD was assessed within each configuration using a repeated-measures ANOVA with test–retest, frequency, and coupler type as within-participants factors. Agreement between the RECD and wRECD was assessed for each coupling configuration using a repeated-measures ANOVA with RECD value, coupler type, and frequency as within-participants factors. Post hoc comparisons with Bonferroni corrections were used when appropriate to locate the frequencies at which differences occurred. A 3-dB criterion was defined to locate differences of clinical significance.Average absolute test–retest differences were within ±3 dB within each coupler and coupling configuration, and between the RECD and wRECD. The RECD and wRECD were in absolute agreement following HA-1-referenced transforms, with most frequencies agreeing within ±1 dB, except at 0.2 kHz for the earmold, and 0.2–0.25 kHz for the foam tip, where the average RECD exceeded the average wRECD by slightly >3 dB.Test–retest repeatability of the RECD (up to 8 kHz) and wRECD (up to 12.5 kHz) is acceptable and similar to previously reported data. The RECD and wRECD are referenced to different couplers, but can be rendered comparable with a simple transform, producing values that are in accordance with the ANSI S3.46-2013 standard.

Extra-High-Frequency Auditory Thresholds: Fine Structure, Reliability, Temporal Integration and Relation to Ear Canal Resonance

1985 ◽  
Vol 24 (2) ◽  
pp. 92-103 ◽  
Author(s):  
Kenneth R. Henry ◽  
Gary A. Fast ◽  
Hanh H. Nguyen ◽  
Marcie C. Paolinelli ◽  
Natalie M. Ayars
Keyword(s):  
Fine Structure ◽  
High Frequency ◽  
Temporal Integration ◽  
Ear Canal ◽  
Auditory Thresholds ◽  
Structure Reliability

scholarly journals Effect of Middle-Ear Pathology on High-Frequency Ear Canal Reflectance Measurements in the Frequency and Time Domains

2019 ◽  
Vol 20 (6) ◽  
pp. 529-552 ◽  
Author(s):  
Gabrielle R. Merchant ◽  
Jonathan H. Siegel ◽  
Stephen T. Neely ◽  
John J. Rosowski ◽  
Hideko H. Nakajima
Keyword(s):  
Middle Ear ◽  
High Frequency ◽  
Ear Canal ◽  
Time Domains ◽  
Reflectance Measurements
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