Browsing by Subject "sound localization"

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    Data supporting Lung-to-ear sound transmission does not improve directional hearing in green treefrogs (Hyla cinerea)
    (2020-09-04) Christensen-Dalsgaard, Jakob; Lee, Norman; Bee, Mark A; mbee@umn.edu; Bee, Mark A
    Amphibians are unique among extant vertebrates in having middle ear cavities that are internally coupled to each other and to the lungs. In frogs, the lung-to-ear sound transmission pathway can influence the tympanum’s inherent directionality, but what role such effects might play in directional hearing remain unclear. In this study of the American green treefrog (Hyla cinerea), we tested the hypothesis that the lung-to-ear sound transmission pathway functions to improve directional hearing, particularly in the context of intraspecific sexual communication. Using laser vibrometry, we measured the tympanum’s vibration amplitude in females in response to a frequency modulated sweep presented from 12 sound incidence angles in azimuth. Tympanum directionality was determined across three states of lung inflation (inflated, deflated, reinflated) both for a single tympanum in the form of the vibration amplitude difference (VAD) and for binaural comparisons in the form of the interaural vibration amplitude difference (IVAD). The state of lung inflation had negligible effects (typically less than 0.5 dB) on both VADs and IVADs at frequencies emphasized in the advertisement calls produced by conspecific males (834 Hz and 2730 Hz). Directionality at the peak resonance frequency of the lungs (1558 Hz) was improved by ≅ 3 dB for a single tympanum when the lungs were inflated versus deflated, but IVADs were not impacted by the state of lung inflation. Based on these results, we reject the hypothesis that the lung-to-ear sound transmission pathway functions to improve directional hearing in frogs.
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    The Relevance of the Inner Ear and Lateral Line System for Sound Localization in Fish
    (2017-02) Cardinal, Emily
    A long standing question in the field of neuroethology is how do fish localize sound? Fish are capable of detecting acoustic information through both an auditory system, the otolithic inner ear, and a mechanosensory system, the lateral line. Both systems are sensory hair cell based and exhibit directional sensitivity responses. Although the fundamental “auditory” anatomy is well characterized in fish, the physiological mechanism of how each system specifically aids in sound source detection is unknown. Using interaural time delays (ITDs) between sensory organs is the well characterized mechanism for terrestrial species sound localization; however, due to the rapid speed of sound underwater and the close proximity of otolithic organs in fish, using ITDs to localize sound is problematic. Alternatively, the conserved lateral line system in fish contains sensory organs located around the entire body, posing a potential sensory system capable of ITDs sufficient for sound localization. The inner ear also plays a dual role functioning in both the auditory and vestibular system, which further questions its potential for acute sound localization during self-induced movements, such as swimming and ventilation. Therefore, the lateral line system may provide additional information about the direction and distance of a sound source that the inner ear in fish cannot.
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    Sound Localization Data of 29 Participants in Bicycle Alarm Development Study collected in 2018 at the University of Minnesota
    (2020-02-26) Morris, Nichole L; Craig, Curtis M; nlmorris@umn.edu; Morris, Nichole L; University of Minnesota HumanFIRST Lab
    This data file represents de-identified raw data from a sound localization experiment with 29 participants. Participants heard an experimental sound (Sound A.wav) or a car horn sound (vehicle045.wav) and had to indicate which direction of the sound. Also included are the sound files used in the study.