scholarly journals Functional Analyses of Peripheral Auditory System Adaptations for Echolocation in Air vs. Water

2021 ◽  
Vol 9 ◽  
Author(s):  
Darlene R. Ketten ◽  
James A. Simmons ◽  
Hiroshi Riquimaroux ◽  
Andrea Megela Simmons
Keyword(s):  
Auditory System ◽  
Basilar Membrane ◽  
Round Window ◽  
Low Frequency ◽  
Radius Of Curvature ◽  
Width Ratio ◽  
Membrane Thickness ◽  
Ultrasonic Frequency ◽  
Harbor Porpoise ◽  
Peripheral Auditory System

The similarity of acoustic tasks performed by odontocete (toothed whale) and microchiropteran (insectivorous bat) biosonar suggests they may have common ultrasonic signal reception and processing mechanisms. However, there are also significant media and prey dependent differences, notably speed of sound and wavelengths in air vs. water, that may be reflected in adaptations in their auditory systems and peak spectra of out-going signals for similarly sized prey. We examined the anatomy of the peripheral auditory system of two species of FM bat (big brown bat Eptesicus fuscus; Japanese house bat Pipistrellus abramus) and two toothed whales (harbor porpoise Phocoena phocoena; bottlenose dolphin Tursiops truncatus) using ultra high resolution (11–100 micron) isotropic voxel computed tomography (helical and microCT). Significant differences were found for oval and round window location, cochlear length, basilar membrane gradients, neural distributions, cochlear spiral morphometry and curvature, and basilar membrane suspension distributions. Length correlates with body mass, not hearing ranges. High and low frequency hearing range cut-offs correlate with basilar membrane thickness/width ratios and the cochlear radius of curvature. These features are predictive of high and low frequency hearing limits in all ears examined. The ears of the harbor porpoise, the highest frequency echolocator in the study, had significantly greater stiffness, higher basal basilar membrane ratios, and bilateral bony support for 60% of the basilar membrane length. The porpoise’s basilar membrane includes a “foveal” region with “stretched” frequency representation and relatively constant membrane thickness/width ratio values similar to those reported for some bat species. Both species of bats and the harbor porpoise displayed unusual stapedial input locations and low ratios of cochlear radii, specializations that may enhance higher ultrasonic frequency signal resolution and deter low frequency cochlear propagation.

Influence of ossicular chain malformation on the performance of round-window stimulation: A finite element approach

2019 ◽  
Vol 233 (5) ◽  
pp. 584-594 ◽  
Author(s):  
Houguang Liu ◽  
Hu Zhang ◽  
Jianhua Yang ◽  
Xinsheng Huang ◽  
Wen Liu ◽  
...  
Keyword(s):  
Finite Element ◽  
Middle Ear ◽  
Basilar Membrane ◽  
Round Window ◽  
Low Frequency ◽  
Element Model ◽  
Ossicular Chain ◽  
Asymmetric Structure ◽  
Low Frequencies ◽  
Stapes Fixation

As a novel application of implantable middle ear hearing device, round-window stimulation is widely used to treat hearing loss with middle ear disease, such as ossicular chain malformation. To evaluate the influence of ossicular chain malformations on the efficiency of the round-window stimulation, a human ear finite element model, which incorporates cochlear asymmetric structure, was constructed. Five groups of comparison with experimental data confirmed the model’s validity. Based on this model, we investigated the influence of three categories of ossicular chain malformations, that is, incudostapedial disconnection, incus and malleus fixation, and fixation of the stapes. These malformations’ effects were evaluated by comparing the equivalent sound pressures derived from the basilar membrane displacement. Results show that the studied ossicular chain malformations mainly affected the round-window simulation’s performance at low frequencies. In contrast to the fixation of the ossicles, which mainly deteriorates round-window simulation’s low-frequency performance, incudostapedial disconnection increases this performance, especially in the absence of incus process and stapes superstructure. Among the studied ossicular chain malformations, the stapes fixation has a much more severe impact on the round-window stimulation’s efficiency. Thus, the influence of the patients’ ossicular chain malformations should be considered in the design of the round-window stimulation’s actuator. The low-frequency output of the round-window simulation’s actuator should be enhanced, especially for treating the patients with stapes fixation.

Neurophysiological Correlates of Auditory Maturation

1980 ◽  
Vol 89 (5_suppl) ◽  
pp. 103-113 ◽  
Author(s):  
Eric Javel
Keyword(s):  
Auditory System ◽  
Cochlear Nucleus ◽  
Physiological Response ◽  
Time Course ◽  
Low Frequency ◽  
Developmental Time ◽  
Response Property ◽  
Central System ◽  
Response Properties ◽  
Peripheral Auditory System

At the time of its birth, the auditory system of the cat is not completely developed. Anatomic maturity of the peripheral auditory system, ie, the cochlea, auditory nerve and cochlear nucleus, is attained at about two or three weeks of age. Physiological response properties of neural elements of the peripheral auditory system change radically during the first few weeks of life, with most measures of responsiveness to acoustic stimuli reaching adult status by the end of the third or fourth postnatal week. The physiological maturation of neural responses correlates well with the anatomic maturation of the auditory structures. At least one physiological response property, namely the ability of cochlear nucleus neurons to time their discharges in response to low-frequency tones, is not fully achieved until the sixth postnatal week or later. Although considerably less is known about the development of the central auditory system, it appears that it is in part dependent upon the maturation of more peripheral elements. Auditory evoked responses, for example, follow roughly the same developmental time course as do the majority of response properties of peripheral neurons. This implies that the central system is ready to function at birth, but that it must await the maturation of more peripheral elements before it can function properly. In contrast to that of the cat and other mammals, the auditory system of the human is relatively well advanced at birth. Certain aspects of brain development, such as dendritic aborization and axonal myelination, undergo considerable change postnatally. How these factors influence hearing is not known.

Post-Metamorphic Development of the Frequency Selectivities and Sensitivities of the Peripheral Auditory System of the Bullfrog, Rana Catesbeiana

1981 ◽  
Vol 93 (1) ◽  
pp. 181-196
Author(s):  
WILLIAM P. SHOFNER ◽  
ALBERT S. FENG
Keyword(s):  
Auditory System ◽  
Rana Catesbeiana ◽  
Morphological Changes ◽  
Low Frequency ◽  
Functional Changes ◽  
Tuning Curves ◽  
Response Characteristics ◽  
Metamorphic Development ◽  
Frequency Selective ◽  
Peripheral Auditory System

Acoustic response characteristics of single fibres were studied in the VIIIth cranial nerve of adult and early post-metamorphic bullfrogs (Rana catesbeiana). Based on the distribution of units' best excitatory frequencies, three populations of auditory fibres were found in each group of frogs. The sharpness of the tuning curves and temporal firing patterns of primary fibres were similar in both adults and froglets. However, the distributions of the populations were different between the two groups, and it was found that froglets responded to higher frequencies than did adults. There were also differences in the distributions of thresholds of excitation between the froglets and adults. The excitation thresholds of low-frequency selective and high-frequency selective fibres tended to be higher in froglets. Low-frequency selective fibres in both groups of frogs exhibited two-tone inhibition, and the best inhibitory frequencies were higher in froglets than in adults. These results demonstrate that changes in the response properties of primary auditory fibres occur during the development of the bullfrog. These functional changes presumably reflect morphological changes which may occur in the peripheral auditory system. Note:

Coding of sounds in lower levels of the auditory system

1972 ◽  
Vol 5 (1) ◽  
pp. 59-155 ◽  
Author(s):  
Aage R. Møller
Keyword(s):  
Auditory System ◽  
Basilar Membrane ◽  
Spatial Differentiation ◽  
Sound Intensity ◽  
Sensory Cells ◽  
Tone Frequency ◽  
Tuning Curves ◽  
Quantitative Measurements ◽  
Peripheral Auditory System ◽  
Line Organ

The great number of investigations and advanced developments in neurophysiology and psychoacoustics during recent years have extensively increased our knowledge about the frequency analysis of simple sounds in the peripheral auditory system.New methods have facilitated quantitative measurements of the amplitude of the submicroscopic vibration of a narrow segment of the basilar membrane in anaesthetized animals at physiological sound intensities. The results of these studies have quantitatively confirmed the results of past studies by showing that the basilar membrane has a selectivity with regard to tone frequency. In addition to this, the recent studies have increased our knowledge about the finer details of vibration of the basilar membrane. At the lowest levels used in the recent investigations, i.e. about 70 dB SPL, the selectivity in the 7 kHz region of the basilar membrane was found to be greater than expected on the basis of extrapolation of older data. Moreover, the high frequency slope of the tuning curves of the basilar membrane was found to be particularly steep. The results of these recent studies, furthermore, showed that the basilar membrane vibrates in a non-linear way at intensities within the physiological range. This non-linearity results in a broadening of the selectivity curves of a narrow segment of the basilar membrane when the sound intensity is increased.Little is known as to how the motion of the basilar membrane is transformed to excitation of the cochlear sensory cells, i.e. the haircells. The excitation may be related to displacement, spatial differentiation or other transformations of the basilar membrane motion. Recording from the interior of mammalian haircells has so far been unsuccessful, and the neural excitatory process within the haircells in the cochlea is as yet practically unknown. Studies of the haircells in the lateral line organ of fish have provided fundamental knowledge about their excitation; since they in many respects resemble those in the mammalian cochlea, the results very probably can be applied to the excitatory process in the mammalian cochlea.

Stochastic resonance in the peripheral auditory system

2014 ◽  
Vol 2 ◽  
pp. 417-420
Author(s):  
Florian Gomez ◽  
Stefan Martignoli ◽  
Ruedi Stoop
Keyword(s):  
Stochastic Resonance ◽  
Auditory System ◽  
Peripheral Auditory System

scholarly journals Auditory and Vestibular Functioning in Individuals with Type-2 Diabetes Mellitus: A Systematic Review

2021 ◽  
Author(s):  
Prawin Kumar ◽  
Niraj Kumar Singh ◽  
Kumari Apeksha ◽  
Vipin Ghosh ◽  
Raveendran Rajesh Kumar ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Systematic Review ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Auditory System ◽  
Microvascular Complications ◽  
Data Synthesis ◽  
Vestibular Tests ◽  
Peripheral Auditory System

Abstract Introduction Diabetes mellitus is a metabolic disease associated with a rise in the level of blood glucose. Individuals with diabetes mellitus are more likely to develop hearing loss, tinnitus, and dizziness due to macro- and microvascular complications. The extent to which auditory and vestibular functions are impaired in individuals with type-2 diabetes mellitus is still under debate. Objective To systematically review studies focusing on auditory and vestibular functions in individuals with type-2 diabetes mellitus. Data Synthesis A search was conducted in the PubMed, MedlinePlus, Ingenta Connect and Google Scholar databases for articles published until June 2019. A total of 15,980 articles were primarily retrieved, 33 of which were shortlisted based on the inclusion criteria set by the investigators for the systematic review. Out of 33 full-length articles, 26 evaluated the functioning of the auditory system, while 7 evaluated the functioning of the vestibular system. Most studies related to auditory functioning reported a significant effect of type-2 diabetes mellitus on the peripheral auditory system, whereas studies on vestibular functioning reported no significant effect of diabetes mellitus on the functioning of the peripheral vestibular end-organ. Conclusion Overall, the results of various audiological and peripheral vestibular tests reveal distinctive peripheral and/or central auditory and vestibular end-organ impairments in individuals with type-2 diabetes mellitus.

scholarly journals Hearing at threshold intensities: by slow mechanical traveling waves or by fast cochlear fluid pressure waves

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Haim Sohmer
Keyword(s):  
Soft Tissue ◽  
Hair Cells ◽  
Traveling Wave ◽  
Basilar Membrane ◽  
Fluid Pressure ◽  
Low Frequency ◽  
Frequency Discrimination ◽  
Outer Hair Cells ◽  
Common Mechanism ◽  
Frequency Stimulation

The three modes of auditory stimulation (air, bone and soft tissue conduction) at threshold intensities are thought to share a common excitation mechanism: the stimuli induce passive displacements of the basilar membrane propagating from the base to the apex (slow mechanical traveling wave), which activate the outer hair cells, producing active displacements, which sum with the passive displacements. However, theoretical analyses and modeling of cochlear mechanics provide indications that the slow mechanical basilar membrane traveling wave may not be able to excite the cochlea at threshold intensities with the frequency discrimination observed. These analyses are complemented by several independent lines of research results supporting the notion that cochlear excitation at threshold may not involve a passive traveling wave, and the fast cochlear fluid pressures may directly activate the outer hair cells: opening of the sealed inner ear in patients undergoing cochlear implantation is not accompanied by threshold elevations to low frequency stimulation which would be expected to result from opening the cochlea, reducing cochlear impedance, altering hydrodynamics. The magnitude of the passive displacements at threshold is negligible. Isolated outer hair cells in fluid display tuned mechanical motility to fluid pressures which likely act on stretch sensitive ion channels in the walls of the cells. Vibrations delivered to soft tissue body sites elicit hearing. Thus, based on theoretical and experimental evidence, the common mechanism eliciting hearing during threshold stimulation by air, bone and soft tissue conduction may involve the fast-cochlear fluid pressures which directly activate the outer hair cells.

Finite Element Model of Human Cochlea Considering of the Helicotrema Size

2013 ◽  
Vol 456 ◽  
pp. 576-581 ◽  
Author(s):  
Li Fu Xu ◽  
Na Ta ◽  
Zhu Shi Rao ◽  
Jia Bin Tian
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Basilar Membrane ◽  
Round Window ◽  
Element Model ◽  
Oval Window ◽  
Fe Model ◽  
Cochlear Duct ◽  
Human Cochlea ◽  
Set Up

A 2-D finite element model of human cochlea is established in this paper. This model includes the structure of oval window, round window, basilar membrane and cochlear duct which is filled with fluid. The basilar membrane responses are calculated with sound input on the oval window membrane. In order to study the effects of helicotrema on basilar membrane response, three different helicotrema dimensions are set up in the FE model. A two-way fluid-structure interaction numerical method is used to compute the responses in the cochlea. The influence of the helicotrema is acquired and the frequency selectivity of the basilar membrane motion along the cochlear duct is predicted. These results agree with the experiments and indicate much better results are obtained with appropriate helicotrema size.

Optimization of Chlorella pyrenoidosa Removal by Low Frequency Ultrasonic Irradiation Using Response Surface Design

2011 ◽  
Vol 295-297 ◽  
pp. 1860-1865 ◽  
Author(s):  
Zhi Zhang ◽  
Chao Liu ◽  
Gong Duan Fan ◽  
Jing Luo ◽  
Yan Dong Wang
Keyword(s):  
Response Surface ◽  
Irradiation Time ◽  
Removal Rate ◽  
Low Frequency ◽  
Chlorella Pyrenoidosa ◽  
Ultrasonic Frequency ◽  
Ultrasonic Power ◽  
Control Parameters ◽  
Single Factor ◽  
Surface Design

The control parameters of the removal of Chlorella pyrenoidosa, which was irradiated by low frequency ultrasonic, is optimized by using single factor experiments and response surface methodology (RSM). First of all, the approximate ranges of the ultrasonic frequency, the ultrasonic power and the irradiation time were estimated with single factor experiments for the further experiments. And then the optimized values of the three control parameters were determined, which were analyzed by using central composite design (CCD) and RSM. The results showed that the removal rate of chlorophyll-a could reach to 64.1% after the irradiation for 6.34min by using ultrasonic of 77.7 kHz and 250W. Ultrasonic technology can remove Chlorella pyrenoidosa cells in water quickly and effectively, so as to achieve the purpose of water purification.

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