scholarly journals Seismic sensitivity and bone conduction mechanisms enable extratympanic hearing in salamanders

2020 ◽  
Vol 223 (24) ◽  
pp. jeb236489
Author(s):  
G. Capshaw ◽  
D. Soares ◽  
J. Christensen-Dalsgaard ◽  
C. E. Carr
Keyword(s):  
Sound Pressure ◽  
Bone Conduction ◽  
Low Frequency ◽  
Threshold Level ◽  
Auditory Brainstem ◽  
Common Mechanism ◽  
Experimental Conditions ◽  
Airborne Sound ◽  
Sound Detection ◽  
Brainstem Response

ABSTRACTThe tympanic middle ear is an adaptive sensory novelty that evolved multiple times in all the major terrestrial tetrapod groups to overcome the impedance mismatch generated when aerial sound encounters the air–skin boundary. Many extant tetrapod species have lost their tympanic middle ears, yet they retain the ability to detect airborne sound. In the absence of a functional tympanic ear, extratympanic hearing may occur via the resonant qualities of air-filled body cavities, sensitivity to seismic vibration, and/or bone conduction pathways to transmit sound from the environment to the ear. We used auditory brainstem response recording and laser vibrometry to assess the contributions of these extratympanic pathways for airborne sound in atympanic salamanders. We measured auditory sensitivity thresholds in eight species and observed sensitivity to low-frequency sound and vibration from 0.05–1.2 kHz and 0.02–1.2 kHz, respectively. We determined that sensitivity to airborne sound is not facilitated by the vibrational responsiveness of the lungs or mouth cavity. We further observed that, although seismic sensitivity probably contributes to sound detection under naturalistic scenarios, airborne sound stimuli presented under experimental conditions did not produce vibrations detectable to the salamander ear. Instead, threshold-level sound pressure is sufficient to generate translational movements in the salamander head, and these sound-induced head vibrations are detectable by the acoustic sensors of the inner ear. This extratympanic hearing mechanism mediates low-frequency sensitivity in vertebrate ears that are unspecialized for the detection of aerial sound pressure, and may represent a common mechanism for terrestrial hearing across atympanic tetrapods.

scholarly journals Bone conduction pathways confer directional cues to salamanders

2021 ◽  
Author(s):  
G. Capshaw ◽  
J. Christensen-Dalsgaard ◽  
D. Soares ◽  
C. E. Carr
Keyword(s):  
Evolutionary History ◽  
Sound Pressure ◽  
Bone Conduction ◽  
Auditory Brainstem ◽  
Directional Hearing ◽  
Sound Detection ◽  
Brainstem Response ◽  
Sound Reception ◽  
Detection And Localization ◽  
Mechanical Disturbances

Sound and vibration are generated by mechanical disturbances within the environment, and the ability to detect and localize these acoustic cues is generally important for survival, as suggested by the early emergence of inherently directional otolithic ears in vertebrate evolutionary history. However, fossil evidence indicates that the water-adapted ear of early terrestrial tetrapods lacked specialized peripheral structures to transduce sound pressure (e.g., tympana). Early terrestrial hearing therefore should have required nontympanic (or extratympanic) mechanisms for sound detection and localization. Here we used atympanate salamanders to investigate the efficacy of extratympanic pathways to support directional hearing in air. We assessed peripheral encoding of directional acoustic information using directionally-masked auditory brainstem response recordings. We used laser Doppler vibrometry to measure the velocity of sound pressure-induced head vibrations as a key extratympanic mechanism for aerial sound reception in atympanate species. We found that sound generates head vibrations that vary with the angle of the incident sound. This extratympanic pathway for hearing supports a figure-eight pattern of directional auditory sensitivity to airborne sound in the absence of a pressure-transducing tympanic ear.

Bone conduction auditory brainstem responses in infants

2004 ◽  
Vol 118 (2) ◽  
pp. 117-122 ◽  
Author(s):  
P. E. Campbell ◽  
C. M. Harris ◽  
S. Hendricks ◽  
T. Sirimanna
Keyword(s):  
Hearing Loss ◽  
Dynamic Range ◽  
Bone Conduction ◽  
Low Frequency ◽  
Paediatric Population ◽  
Auditory Brainstem ◽  
Sensorineural Hearing ◽  
Auditory Brainstem Responses ◽  
Brainstem Response ◽  
Narrow Dynamic Range

The contribution of air conduction auditory brainstem response (AC-ABR) testing in the paediatric population is widely accepted in clinical audiology. However, this does not allow for differentiation between conductive and sensorineural hearing loss. The purpose ofthis paper is to review the role of bone conduction auditory brainstem responses (BC-ABR). It is argued that despite such technical difficulties as a narrow dynamic range, masking dilemmas, stimulus artifact and low frequency underestimation of hearing loss, considerable evidence exists to suggest that BC-ABR testing provides an important contribution in the accurate assessmentof hearing loss in infants. Modification of the BC-ABR protocol is discussed and the technical difficulties that may arise are addressed, permitting BC-ABR to be used as a tool in the differential diagnosis between conductive and sensorineural hearing. Two relevant case studies are presented to highlight the growing importance of appropriate management in early identification of hearing loss. It can be concluded that BC-ABR should be adopted as a routine clinical diagnostic tool.

scholarly journals Earless toads sense low frequencies but miss the high notes

2017 ◽  
Vol 284 (1864) ◽  
pp. 20171670 ◽  
Author(s):  
Molly C. Womack ◽  
Jakob Christensen-Dalsgaard ◽  
Luis A. Coloma ◽  
Juan C. Chaparro ◽  
Kim L. Hoke
Keyword(s):  
High Frequency ◽  
Species Differences ◽  
Low Frequency ◽  
Auditory Brainstem ◽  
Low Frequencies ◽  
Hearing Sensitivity ◽  
Sensory Pathways ◽  
Airborne Sound ◽  
Vibrational Sensitivity ◽  
Species Specific

Sensory losses or reductions are frequently attributed to relaxed selection. However, anuran species have lost tympanic middle ears many times, despite anurans' use of acoustic communication and the benefit of middle ears for hearing airborne sound. Here we determine whether pre-existing alternative sensory pathways enable anurans lacking tympanic middle ears (termed earless anurans) to hear airborne sound as well as eared species or to better sense vibrations in the environment. We used auditory brainstem recordings to compare hearing and vibrational sensitivity among 10 species (six eared, four earless) within the Neotropical true toad family (Bufonidae). We found that species lacking middle ears are less sensitive to high-frequency sounds, however, low-frequency hearing and vibrational sensitivity are equivalent between eared and earless species. Furthermore, extratympanic hearing sensitivity varies among earless species, highlighting potential species differences in extratympanic hearing mechanisms. We argue that ancestral bufonids may have sufficient extratympanic hearing and vibrational sensitivity such that earless lineages tolerated the loss of high frequency hearing sensitivity by adopting species-specific behavioural strategies to detect conspecifics, predators and prey.

Low-Frequency Auditory Brainstem Response Threshold

1988 ◽  
Vol 17 (3) ◽  
pp. 171-178 ◽  
Author(s):  
E. Laukli ◽  
O. Fjermedal ◽  
I. W. S. Mair
Keyword(s):  
Auditory Brainstem Response ◽  
Low Frequency ◽  
Auditory Brainstem ◽  
Response Threshold ◽  
Brainstem Response

Hearing thresholds of small native Australian mammals – red-tailed phascogale (Phascogale calura), kultarr (Antechinomys laniger) and spinifex hopping-mouse (Notomys alexis)

2020 ◽  
Vol 190 (1) ◽  
pp. 342-351 ◽  
Author(s):  
Julie M Old ◽  
Carl Parsons ◽  
Melissa L Tulk
Keyword(s):  
Sound Pressure ◽  
Dynamic Range ◽  
Auditory Brainstem ◽  
Natural Environments ◽  
Predator Detection ◽  
Future Studies ◽  
Hearing Thresholds ◽  
Brainstem Response ◽  
Hearing Range ◽  
High Range

Abstract Hearing is essential for communication, to locate prey and to avoid predators. We addressed the paucity of information regarding hearing in Australian native mammals by specifically assessing the hearing range and sensitivity of the red-tailed phascogale (Phascogale calura), the kultarr (Antechinomys laniger) and the spinifex hopping-mouse (Notomys alexis). Auditory brainstem response (ABR) audiograms were used to estimate hearing thresholds within the range of 1–84 kHz, over a dynamic range of 0–80 dB sound pressure level (SPL). Phascogales had a hearing range of 1–40 kHz, kultarrs 1–35 kHz and hopping-mice 1–35 kHz, with a dynamic range of 17–59 dB SPL, 20–80 dB SPL and 30–73 dB SPL, respectively. Hearing for all species was most sensitive at 8 kHz. Age showed no influence on optimal hearing, but younger animals had more diverse optimal hearing frequencies. There was a relationship between males and their optimal hearing frequency, and greater interaural distances of individual males may be related to optimal hearing frequency. Because nocturnal animals use high-range hearing for prey or predator detection, our study suggests this may also be the case for the species examined in this study. Future studies should investigate their vocalizations and behaviour in their natural environments, and by exposing them to different auditory stimuli.

Normal Brief-Tone Bone-Conduction Behavioral Thresholds Using the B-71 Transducer: Three Occlusion Conditions

2003 ◽  
Vol 14 (10) ◽  
pp. 556-562 ◽  
Author(s):  
Susan A. Small ◽  
David R. Stapells
Keyword(s):  
Auditory Brainstem Response ◽  
Pure Tone ◽  
Bone Conduction ◽  
Auditory Brainstem ◽  
Behavioral Thresholds ◽  
Brainstem Response ◽  
Occlusion Effect ◽  
Response Testing ◽  
Brief Tones ◽  
Air Conduction

Behavioral thresholds were measured from 31 adults with normal hearing for 500, 1000, 2000, and 4000 Hz brief tones presented using a B-71 bone oscillator. Three occlusion conditions were assessed: ears unoccluded, one ear occluded, and both ears occluded. Mean threshold force levels were 67, 54, 49, and 41 dB re:1μN peak-to-peak equivalent in the unoccluded condition for 500, 1000, 2000, and 4000 Hz, respectively (corrected for air-conduction pure-tone thresholds). A significant occlusion effect was observed for 500 and 1000 Hz stimuli. These thresholds may be used as the 0 dB nHL (normalhearing level) for brief-tone bone-conduction stimuli for auditory brainstem response testing.

scholarly journals Better Understanding of Direct Bone-Conduction Measurement: Comparison with Frequency-Specific Bone-Conduction Tones and Brainstem Responses

2020 ◽  
Vol 24 (2) ◽  
pp. 85-90
Author(s):  
Yeoju Kim ◽  
Woojae Han ◽  
Sihun Park ◽  
Sunghwa You ◽  
Chanbeom Kwak ◽  
...  
Keyword(s):  
Bone Conduction ◽  
Pure Tone Audiometry ◽  
Large Data ◽  
Tone Burst ◽  
Auditory Brainstem ◽  
Current Data ◽  
Data Set ◽  
Low Frequencies ◽  
High Frequencies ◽  
Brainstem Response

Background and Objectives: The present study aimed to compare thresholds of direct bone-conduction (BC direct) with those of behaviorally measured BC pure-tone audiometry (PTA) and objectively measured BC auditory brainstem response (ABR) to confirm the clinical feasibility of their relationships.Subjects and Methods: Young adults with normal hearing participated in the study to determine the thresholds from three measurements at four testing frequencies. In the BC direct, the vibrator of a bone-anchored hearing aid softband was placed on the right mastoid of each subject. In both PTA and ABR, a B71 bone oscillator was placed on the subject’s right mastoid. While the subject’s thresholds of BC direct and BC PTA were determined with a clinically routine 5-dB step procedure, BC ABR was conducted to determine the individual’s hearing sensitivity by a peak V of the waveform using tone-burst and click stimuli.Results: The BC direct showed a different pattern between low and high frequencies. Precisely, its thresholds were 13.25 and 12.25 dB HL at 0.5 and 1 kHz, respectively, but 19 and 19.75 dB HL at 2 and 4 kHz, respectively. A significant positive correlation existed between BC direct and PTA at 1 kHz, which was also correlated with ABR.Conclusions: Based on the current data, the thresholds of BC direct were similar to BC PTA at low frequencies and BC ABR at high frequencies. The thresholds of BC direct might be predictable at approximately 5 dB higher (or lower) than that in PTA, although a large data set is required for standardization.

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