Further evidences of the contribution of the ear canal to directional hearing: Design of a compensation filter

2013 ◽  
Vol 133 (5) ◽  
pp. 3516-3516
Author(s):  
Andrea Martelloni ◽  
Davide A. Mauro ◽  
Antonio Mancuso
Keyword(s):  
Directional Hearing ◽  
Ear Canal

Directional Hearing in the Japanese Quail (Coturnix Coturnix Japonica): II. Cochlear Physiology

1980 ◽  
Vol 86 (1) ◽  
pp. 153-170
Author(s):  
R. B. COLES ◽  
D. B. LEWIS ◽  
K. G. HILL ◽  
M. E. HUTCHINGS ◽  
D. M. GOWER
Keyword(s):  
Pressure Gradient ◽  
Free Field ◽  
Directional Hearing ◽  
Directional Sensitivity ◽  
Ear Canal ◽  
Directional Information ◽  
Cochlear Physiology ◽  
Directivity Patterns ◽  
The Difference ◽  
Sound Diffraction

The directional sensitivity of cochlear microphonics (CM) was studied inthe quail by rotating a free-field sound source (pure tones, 160-10 kHz)through 360° in the horizontal plane, under anechoic conditions. Sound diffraction by the head was monitored simultaneously by a microphone at the entrance to the ipsilateral (recorded) ear canal. Pressure-field fluctuations measured by the microphone were non-directional (≤ 4 dB) up to 4 kHz; the maximum head shadow was 8 dB at 6.3 kHz. In comparison, the CM sensitivity under went directional fluctuations ranging up to 25 dB for certain low, mid and high frequency band widths. There was noticeable variation between quail for frequencies producing maximum directional effects, although consistently poor directionality was seen near 820 Hz andto a lesser extent near 3.5 kHz. Well-defined CM directivity patterns reflected the presence of nulls (insensitive regions) at critical positions around the head and the number of nulls increased with frequency. Five major types of directivity patterns were defined using polar co-ordinates: cardioid, supercardioid, figure-of-eight, tripartite and multilobed. Such patterns were largely unrelated to head shadow effects. Blocking the ear canal contralateral to there corded ear was shown to effectively abolish CM directionality, largely by eliminating regions of insensitivity to sound. It is inferred that the quail ear functions as an asym metrical pressure gradient receiver, the pressure gradient function being mediated by the interauralcavity. It is proposed that the central auditory system codes directional information by a null detecting method and computes an unambiguous (i.e.intensity independent) directional cue. This spatial cue is achieved by the difference between the directional sensitivities of the two ears, defined as the Directional Index (DI). The spatial distribution of DI values (difference pattern) demonstrated ranges and peaks which closely reflected the extent and position of nulls determined from monaural directivity functions. Large directional cues (up to 25 dB) extended throughout most of the audible spectrum of the quail and the sharpness of difference patterns increased with frequency. Primary ‘best’ directions, estimated from peaks in difference patterns, tended to move towards the front of the head at higher frequencies; rearward secondary peaks also occurred. From the properties of directional cues it is suggested that the ability of birds to localize sound need not necessarily depend on frequency; however, spatial acuity may be both frequency and direction dependent, and include the possibility of front-torearerrors. The directional properties of bird vocalizations may need to bere assessed on the basis of the proposed mechanism for directional hearing.

scholarly journals A narrow ear canal reduces sound velocity to create additional acoustic inputs in a microscale insect ear

2021 ◽  
Vol 118 (10) ◽  
pp. e2017281118
Author(s):  
Daniel Veitch ◽  
Emine Celiker ◽  
Sarah Aldridge ◽  
Christian Pulver ◽  
Carl D. Soulsbury ◽  
...  
Keyword(s):  
Tympanic Membrane ◽  
Sound Velocity ◽  
Three Dimensional ◽  
Numerical Data ◽  
Directional Hearing ◽  
Ear Canal ◽  
Tracheal System ◽  
Free Air ◽  
Human Ear ◽  
Main Factor

Located in the forelegs, katydid ears are unique among arthropods in having outer, middle, and inner components, analogous to the mammalian ear. Unlike mammals, sound is received externally via two tympanic membranes in each ear and internally via a narrow ear canal (EC) derived from the respiratory tracheal system. Inside the EC, sound travels slower than in free air, causing temporal and pressure differences between external and internal inputs. The delay was suspected to arise as a consequence of the narrowing EC geometry. If true, a reduction in sound velocity should persist independently of the gas composition in the EC (e.g., air, CO2). Integrating laser Doppler vibrometry, microcomputed tomography, and numerical analysis on precise three-dimensional geometries of each experimental animal EC, we demonstrate that the narrowing radius of the EC is the main factor reducing sound velocity. Both experimental and numerical data also show that sound velocity is reduced further when excess CO2 fills the EC. Likewise, the EC bifurcates at the tympanal level (one branch for each tympanic membrane), creating two additional narrow internal sound paths and imposing different sound velocities for each tympanic membrane. Therefore, external and internal inputs total to four sound paths for each ear (only one for the human ear). Research paths and implication of findings in avian directional hearing are discussed.

scholarly journals Further evidences of the contribution of the ear canal to directional hearing: design of a compensation filter

2013 ◽  
Author(s):  
Andrea Martelloni ◽  
Davide A. Mauro ◽  
Antonio Mancuso
Keyword(s):  
Directional Hearing ◽  
Ear Canal

Hearing Aid Amplification Reduces Communication Effort of People With Hearing Impairment and Their Conversation Partners

2020 ◽  
Vol 63 (4) ◽  
pp. 1299-1311 ◽  
Author(s):  
Timothy Beechey ◽  
Jörg M. Buchholz ◽  
Gitte Keidser
Keyword(s):  
Hearing Impairment ◽  
Hearing Aid ◽  
Normal Hearing ◽  
Referential Communication ◽  
Hearing Impaired ◽  
Directional Hearing ◽  
Acoustic Environment ◽  
Communication Task ◽  
Acoustic Environments ◽  
The Impact

Objectives This study investigates the hypothesis that hearing aid amplification reduces effort within conversation for both hearing aid wearers and their communication partners. Levels of effort, in the form of speech production modifications, required to maintain successful spoken communication in a range of acoustic environments are compared to earlier reported results measured in unaided conversation conditions. Design Fifteen young adult normal-hearing participants and 15 older adult hearing-impaired participants were tested in pairs. Each pair consisted of one young normal-hearing participant and one older hearing-impaired participant. Hearing-impaired participants received directional hearing aid amplification, according to their audiogram, via a master hearing aid with gain provided according to the NAL-NL2 fitting formula. Pairs of participants were required to take part in naturalistic conversations through the use of a referential communication task. Each pair took part in five conversations, each of 5-min duration. During each conversation, participants were exposed to one of five different realistic acoustic environments presented through highly open headphones. The ordering of acoustic environments across experimental blocks was pseudorandomized. Resulting recordings of conversational speech were analyzed to determine the magnitude of speech modifications, in terms of vocal level and spectrum, produced by normal-hearing talkers as a function of both acoustic environment and the degree of high-frequency average hearing impairment of their conversation partner. Results The magnitude of spectral modifications of speech produced by normal-hearing talkers during conversations with aided hearing-impaired interlocutors was smaller than the speech modifications observed during conversations between the same pairs of participants in the absence of hearing aid amplification. Conclusions The provision of hearing aid amplification reduces the effort required to maintain communication in adverse conditions. This reduction in effort provides benefit to hearing-impaired individuals and also to the conversation partners of hearing-impaired individuals. By considering the impact of amplification on both sides of dyadic conversations, this approach contributes to an increased understanding of the likely impact of hearing impairment on everyday communication.

Anatomical Study of the Modified Glasscock Approach with a Temporary Removal of the Bony Ear Canal

Skull Base ◽  
2007 ◽  
Vol 17 (S 1) ◽  
Author(s):  
H. Kunst ◽  
J. Lavieille ◽  
A. Devèze ◽  
K. Graamans ◽  
J. Magnan
Keyword(s):  
Anatomical Study ◽  
Ear Canal

Directional Hearing, Three Different Test-Methods

1973 ◽  
Vol 2 (3) ◽  
pp. 125-131
Author(s):  
R. Nilsson ◽  
G. Lidén ◽  
M. Rosén ◽  
M. Zöller
Keyword(s):  
Test Methods ◽  
Directional Hearing

Rhabdomyosarcoma of the External Ear Canal Treated with Brachytherapy

2016 ◽  
Vol 2016 (1) ◽  
Author(s):  
Mahvish Qureshi MD ◽  
◽  
Sana Farooki MD ◽  
Chibuzo O’Suoji MD ◽  
◽  
...  
Keyword(s):  
External Ear ◽  
Ear Canal ◽  
External Ear Canal
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