Spatial distribution of sound pressure and energy flow in the ear canals of cats

1994 ◽  
Vol 96 (1) ◽  
pp. 170-180 ◽  
Author(s):  
Michael R. Stinson ◽  
Shyam M. Khanna
Keyword(s):  
Spatial Distribution ◽  
Energy Flow ◽  
Sound Pressure ◽  
Ear Canals

scholarly journals A System for Acoustic Field Measurement Employing Cartesian Robot

2016 ◽  
Vol 23 (3) ◽  
pp. 333-343 ◽  
Author(s):  
Maciej Szczodrak ◽  
Adam Kurowski ◽  
Józef Kotus ◽  
Andrzej Czyżewski ◽  
Bożena Kostek
Keyword(s):  
Acoustic Field ◽  
Energy Flow ◽  
Velocity Vector ◽  
Sound Pressure ◽  
Sound Field ◽  
Acoustic Energy ◽  
The Other ◽  
Object Shape ◽  
Movement Path ◽  
Optimum Path

AbstractA system setup for measurements of acoustic field, together with the results of 3D visualisations of acoustic energy flow are presented in the paper. Spatial sampling of the field is performed by a Cartesian robot. Automatization of the measurement process is achieved with the use of a specialized control system. The method is based on measuring the sound pressure (scalar) and particle velocity(vector) quantities. The aim of the system is to collect data with a high precision and repeatability. The system is employed for measurements of acoustic energy flow in the proximity of an artificial head in an anechoic chamber. In the measurement setup an algorithm for generation of the probe movement path is included. The algorithm finds the optimum path of the robot movement, taking into account a given 3D object shape present in the measurement space. The results are presented for two cases, first without any obstacle and the other - with an artificial head in the sound field.

The spatial distribution of sound pressure within the human ear canal

2005 ◽  
Vol 117 (4) ◽  
pp. 2564-2564
Author(s):  
Michael R. Stinson ◽  
Gilles A. Daigle
Keyword(s):  
Spatial Distribution ◽  
Sound Pressure ◽  
Ear Canal ◽  
Human Ear

scholarly journals Sound pressure distribution within natural and artificial human ear canals: Forward stimulation

2014 ◽  
Vol 136 (6) ◽  
pp. 3132-3146 ◽  
Author(s):  
Michael E. Ravicz ◽  
Jeffrey Tao Cheng ◽  
John J. Rosowski
Keyword(s):  
Pressure Distribution ◽  
Sound Pressure ◽  
Ear Canals ◽  
Human Ear

Using Average Correction Factors to Improve the Estimated Sound Pressure Level Near the Tympanic Membrane

2012 ◽  
Vol 23 (09) ◽  
pp. 733-750
Author(s):  
Karrie LaRae Recker ◽  
Tao Zhang ◽  
Weili Lin
Keyword(s):  
Tympanic Membrane ◽  
Sound Pressure Level ◽  
Hearing Aids ◽  
Best Practice ◽  
Sound Pressure ◽  
Pressure Level ◽  
Correction Factors ◽  
Ear Canal ◽  
Frequency Components ◽  
Ear Canals

Background: Sound pressure-based real ear measurements are considered best practice for ensuring audibility among individuals fitting hearing aids. The accuracy of current methods is generally considered clinically acceptable for frequencies up to about 4 kHz. Recent interest in the potential benefits of higher frequencies has brought about a need for an improved, and clinically feasible, method of ensuring audibility for higher frequencies. Purpose: To determine whether (and the extent to which) average correction factors could be used to improve the estimated high-frequency sound pressure level (SPL) near the tympanic membrane (TM). Research Design: For each participant, real ear measurements were made along the ear canal, at 2–16 mm from the TM, in 2-mm increments. Custom in-ear monitors were used to present a stimulus with frequency components up to 16 kHz. Study Sample: Twenty adults with normal middle-ear function participated in this study. Intervention: Two methods of creating and implementing correction factors were tested. Data Collection and Analysis: For Method 1, correction factors were generated by normalizing all of the measured responses along the ear canal to the 2-mm response. From each normalized response, the frequency of the pressure minimum was determined. This frequency was used to estimate the distance to the TM, based on the ¼ wavelength of that frequency. All of the normalized responses with similar estimated distances to the TM were grouped and averaged. The inverse of these responses served as correction factors. To apply the correction factors, the only required information was the frequency of the pressure minimum. Method 2 attempted to, at least partially, account for individual differences in TM impedance, by taking into consideration the frequency and the width of the pressure minimum. Because of the strong correlation between a pressure minimum's width and depth, this method effectively resulted in a group of average normalized responses with different pressure-minimum depths. The inverse of these responses served as correction factors. To apply the correction factors, it was necessary to know both the frequency and the width of the pressure minimum. For both methods, the correction factors were generated using measurements from one group of ten individuals and verified using measurements from a second group of ten individuals. Results: Applying the correction factors resulted in significant improvements in the estimated SPL near the TM for both methods. Method 2 had the best accuracy. For frequencies up to 10 kHz, 95% of measurements had <8 dB of error, which is comparable to the accuracy of real ear measurement methods that are currently used clinically below 4 kHz. Conclusions: Average correction factors can be successfully applied to measurements made along the ear canals of otologically healthy adults, to improve the accuracy of the estimated SPL near the TM in the high frequencies. Further testing is necessary to determine whether these correction factors are appropriate for pediatrics or individuals with conductive hearing losses.

Sound Pressure in Ear Canals Modified by Surgery

1970 ◽  
Vol 13 (2) ◽  
pp. 400-417
Author(s):  
William Melnick
Keyword(s):  
Sound Pressure ◽  
Sound Field ◽  
Effective Length ◽  
Radical Mastoidectomy ◽  
Type Iii ◽  
Sharp Minimum ◽  
Main Effect ◽  
Ear Canals ◽  
Lower Frequencies

This two-part study measured sound pressure using a probe tube microphone in normal and surgically altered ear canals. In the first study sound was generated by a TDH-39 earphone in 24 normal ears and 21 ears exposed to radical mastoidectomy and Type III or IV tympanoplasty. Considered as groups the two types of ears showed little difference in measured sound pressure. The most remarkable observation was a sharp minimum in sound pressure which occurred at the 2000–3000 Hz range in the surgically altered ears but was not seen in the normal ears. The second study measured sound pressure deep in the canal and also at the canal entrance of 20 normal ears and 20 surgical ears in a sound field. The main effect was a shift in observed maxima and minima of sound pressure to lower frequencies in the surgically altered ears indicating an increase in the effective length of the canal. Changes in sound pressure were difficult to isolate audiometrically. The effects of surgery might be expected to influence audiometric results at frequencies above 2000 Hz.

Virtual-space receptive fields of single auditory nerve fibers

1993 ◽  
Vol 70 (2) ◽  
pp. 667-676 ◽  
Author(s):  
P. W. Poon ◽  
J. F. Brugge
Keyword(s):  
Spatial Distribution ◽  
Auditory Nerve ◽  
Sound Pressure ◽  
Nerve Fibers ◽  
Virtual Space ◽  
Acoustic Properties ◽  
High Background ◽  
Single Fibers ◽  
Auditory Nerve Fibers ◽  
Acoustic Space

1. Sounds reaching the tympanic membranes are first modified by the acoustic properties of the torso, head, and external ear. For certain frequencies in the incident sound there results a complex, direction-dependent spatial distribution of sound pressure at the eardrum such that, within a sound field, localized areas of pressure maxima are flanked by areas of pressure minima. Listeners may use these spatial maxima and minima in localizing the source of a sound in space. The results presented describe how information about this spatial pressure pattern is transmitted from the cochlea to the central auditory system via single fibers of the auditory nerve. 2. Discharges of single fibers of the auditory nerve were studied in Nembutal-anesthetized cats [characteristic frequencies (CFs) ranged from 0.4 to 40 kHz]. Click stimuli were derived from sound-pressure waveforms that were generated by a loudspeaker placed at 1,800 locations around the cat's head and recorded at the tympanic membrane with miniature microphones. Recorded signals were converted to acoustic stimuli and delivered to the ear via a calibrated and sealed earphone. The full complement of signals is referred to as "virtual acoustic space," and the spatial distribution of discharges to this array of signals is referred to as a "virtual-space receptive field" (VSRF). 3. Fibers detect both pressure maxima and pressure minima in virtual acoustic space. Thus VSRFs take on complex shapes. 4. VSRFs of fibers of the same or similar CF having low spontaneous rates had the same overall pattern as those from high-spontaneous rate (HSR) fibers. For HSR fibers, the VSRF is obscured by the high background spike activity. 5. Comparison of the VSRF and isolevel contour maps of the stimulus derived at various frequencies revealed that auditory nerve fibers most accurately extract spectral information contained in the stimulus at a frequency close to or slightly higher than CF.

Sign in / Sign up

Export Citation Format

Share Document