{"id":{"repo_id":"umn","oai_identifier":"oai:conservancy.umn.edu:11299/278801"},"canonical_url":"https://search.dev.ndltd.org/etd/umn/oai:conservancy.umn.edu:11299/278801","repository":{"repo_id":"umn","name":"University of Minnesota","base_url":"https://conservancy.umn.edu/server/oai/request"},"display":{"title":"Investing the effects of body-coupled ultrasound on the auditory system for a novel hearing aid","abstract":"Ultrasound stimulation (US) is a popular therapeutic tool that has been shown to induce auditory perceptions when coupled to the mastoid of human subjects. This technology has the potential to create new hearing devices that provide benefits that traditional hearing prosthetics are not able due to the higher stimulation frequencies of ultrasound. However, there are no studies that investigate in depth how the activation of ultrasound influences the neural activity and how encoding information in US manifests in the central nucleus of the inferior colliculus (ICC). Numerous studies that have investigated ultrasound perception (USP) attribute this perceptual effect to a bone conduction pathway, even though further studies in animal subjects have demonstrated that the fluids in the cochlea are a central component in the activation of the auditory system. Here, we present research in which we stimulated guinea pigs with US and performed invasive extracellular recordings to identify the relationship between US and evoked neural activity. The stimuli consisted of simple unmodulated ultrasound waveforms, to identify the relationship between ultrasound intensity and neural activity, as well as modulated ultrasound waveforms, to investigate how encoding meaningful information manifests in the neural rate code. We also tested how the presence of the skull and ultrasound transducer placement affect the neural response to understand the role of the skull as a transmission pathway for ultrasound. We observed that unmodulated ultrasound primarily activates the high-frequency regions of the cochlea, and that at low levels of ultrasound the evoked activity is comparable to conversational sound levels in these regions. These results suggest that high-level ultrasound can induce wide activation of the auditory system, and potentially drive startle responses often thought of as direct activation of motor circuits. We also observed that removing the skull or placing the transducer closer to the target cochlea increases the overall evoked neural activity, suggesting that ultrasound activation of the auditory system differs from bone conduction in significant and meaningful ways. Modulating ultrasound with simple tones reliably activates the auditory system in a similar way to pure tones presented via traditional air conduction mechanisms particularly in cochlear regions below 20 kHz, even at low ultrasound pressures. When ultrasound is modulated with more complex waveforms, such as guinea pig vocalizations, the ICC responds in similar temporal patterns as when the vocalizations are presented in traditional ways. We developed generalized linear models (GLMs) to capture these neural dynamics and compared the spike rates when evoked via different modalities. Finally, our studies demonstrate different response patterns when the vocalizations were presented via bone conductor or ultrasound stimulation, further suggesting that ultrasound transducers differ from traditional bone conductors in the method they activate the cochlea, suggesting that a high frequency ultrasound hearing aid can provide therapeutic benefits that differ from traditional hearing aid devices. Further understanding on how high frequency ultrasound activates the auditory system can help clarify the perceptual properties of ultrasound as well as the mechanisms by which this technology interacts with the rest of the nervous system.","abstract_html":"Ultrasound stimulation (US) is a popular therapeutic tool that has been shown to induce auditory perceptions when coupled to the mastoid of human subjects. This technology has the potential to create new hearing devices that provide benefits that traditional hearing prosthetics are not able due to the higher stimulation frequencies of ultrasound. However, there are no studies that investigate in depth how the activation of ultrasound influences the neural activity and how encoding information in US manifests in the central nucleus of the inferior colliculus (ICC). Numerous studies that have investigated ultrasound perception (USP) attribute this perceptual effect to a bone conduction pathway, even though further studies in animal subjects have demonstrated that the fluids in the cochlea are a central component in the activation of the auditory system. Here, we present research in which we stimulated guinea pigs with US and performed invasive extracellular recordings to identify the relationship between US and evoked neural activity. The stimuli consisted of simple unmodulated ultrasound waveforms, to identify the relationship between ultrasound intensity and neural activity, as well as modulated ultrasound waveforms, to investigate how encoding meaningful information manifests in the neural rate code. We also tested how the presence of the skull and ultrasound transducer placement affect the neural response to understand the role of the skull as a transmission pathway for ultrasound. We observed that unmodulated ultrasound primarily activates the high-frequency regions of the cochlea, and that at low levels of ultrasound the evoked activity is comparable to conversational sound levels in these regions. These results suggest that high-level ultrasound can induce wide activation of the auditory system, and potentially drive startle responses often thought of as direct activation of motor circuits. We also observed that removing the skull or placing the transducer closer to the target cochlea increases the overall evoked neural activity, suggesting that ultrasound activation of the auditory system differs from bone conduction in significant and meaningful ways. Modulating ultrasound with simple tones reliably activates the auditory system in a similar way to pure tones presented via traditional air conduction mechanisms particularly in cochlear regions below 20 kHz, even at low ultrasound pressures. When ultrasound is modulated with more complex waveforms, such as guinea pig vocalizations, the ICC responds in similar temporal patterns as when the vocalizations are presented in traditional ways. We developed generalized linear models (GLMs) to capture these neural dynamics and compared the spike rates when evoked via different modalities. Finally, our studies demonstrate different response patterns when the vocalizations were presented via bone conductor or ultrasound stimulation, further suggesting that ultrasound transducers differ from traditional bone conductors in the method they activate the cochlea, suggesting that a high frequency ultrasound hearing aid can provide therapeutic benefits that differ from traditional hearing aid devices. Further understanding on how high frequency ultrasound activates the auditory system can help clarify the perceptual properties of ultrasound as well as the mechanisms by which this technology interacts with the rest of the nervous system.","abstract_has_math":false,"creators":["Rodriguez Orellana, Gerardo"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2023,"date_issued":"2023-08","date_published":"2023-08","updated_at":"2026-07-24T05:19:48Z","subjects":["Auditory System","Bone conduction","Electrophysiology","Hearing devices","Ultrasound"],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/11299/278801","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Rodriguez Orellana, Gerardo"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2026-02-12T17:45:44Z"]},{"key":"dc:date.issued","label":"Date","values":["2023-08"]},{"key":"dc:type","label":"Dc Type","values":["Thesis or Dissertation"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Auditory System","Bone conduction","Electrophysiology","Hearing devices","Ultrasound"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/11299/278801"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["University of Minnesota Ph.D. dissertation. August 2023. Major: Biomedical Engineering. Advisor: Hubert Lim. 1 computer file (PDF); xxv, 183 pages."]},{"key":"dc:description.abstract","label":"Abstract","values":["Ultrasound stimulation (US) is a popular therapeutic tool that has been shown to induce auditory perceptions when coupled to the mastoid of human subjects. This technology has the potential to create new hearing devices that provide benefits that traditional hearing prosthetics are not able due to the higher stimulation frequencies of ultrasound. However, there are no studies that investigate in depth how the activation of ultrasound influences the neural activity and how encoding information in US manifests in the central nucleus of the inferior colliculus (ICC). Numerous studies that have investigated ultrasound perception (USP) attribute this perceptual effect to a bone conduction pathway, even though further studies in animal subjects have demonstrated that the fluids in the cochlea are a central component in the activation of the auditory system. Here, we present research in which we stimulated guinea pigs with US and performed invasive extracellular recordings to identify the relationship between US and evoked neural activity. The stimuli consisted of simple unmodulated ultrasound waveforms, to identify the relationship between ultrasound intensity and neural activity, as well as modulated ultrasound waveforms, to investigate how encoding meaningful information manifests in the neural rate code. We also tested how the presence of the skull and ultrasound transducer placement affect the neural response to understand the role of the skull as a transmission pathway for ultrasound. We observed that unmodulated ultrasound primarily activates the high-frequency regions of the cochlea, and that at low levels of ultrasound the evoked activity is comparable to conversational sound levels in these regions. These results suggest that high-level ultrasound can induce wide activation of the auditory system, and potentially drive startle responses often thought of as direct activation of motor circuits. We also observed that removing the skull or placing the transducer closer to the target cochlea increases the overall evoked neural activity, suggesting that ultrasound activation of the auditory system differs from bone conduction in significant and meaningful ways. Modulating ultrasound with simple tones reliably activates the auditory system in a similar way to pure tones presented via traditional air conduction mechanisms particularly in cochlear regions below 20 kHz, even at low ultrasound pressures. When ultrasound is modulated with more complex waveforms, such as guinea pig vocalizations, the ICC responds in similar temporal patterns as when the vocalizations are presented in traditional ways. We developed generalized linear models (GLMs) to capture these neural dynamics and compared the spike rates when evoked via different modalities. Finally, our studies demonstrate different response patterns when the vocalizations were presented via bone conductor or ultrasound stimulation, further suggesting that ultrasound transducers differ from traditional bone conductors in the method they activate the cochlea, suggesting that a high frequency ultrasound hearing aid can provide therapeutic benefits that differ from traditional hearing aid devices. Further understanding on how high frequency ultrasound activates the auditory system can help clarify the perceptual properties of ultrasound as well as the mechanisms by which this technology interacts with the rest of the nervous system."]},{"key":"dc:title","label":"Title","values":["Investing the effects of body-coupled ultrasound on the auditory system for a novel hearing aid"]}]}],"canonical_facts":{"dc:creator":["Rodriguez Orellana, Gerardo"],"dc:date.accessioned":["2026-02-12T17:45:44Z"],"dc:date.issued":["2023-08"],"dc:description":["University of Minnesota Ph.D. dissertation. August 2023. Major: Biomedical Engineering. Advisor: Hubert Lim. 1 computer file (PDF); xxv, 183 pages."],"dc:description.abstract":["Ultrasound stimulation (US) is a popular therapeutic tool that has been shown to induce auditory perceptions when coupled to the mastoid of human subjects. This technology has the potential to create new hearing devices that provide benefits that traditional hearing prosthetics are not able due to the higher stimulation frequencies of ultrasound. However, there are no studies that investigate in depth how the activation of ultrasound influences the neural activity and how encoding information in US manifests in the central nucleus of the inferior colliculus (ICC). Numerous studies that have investigated ultrasound perception (USP) attribute this perceptual effect to a bone conduction pathway, even though further studies in animal subjects have demonstrated that the fluids in the cochlea are a central component in the activation of the auditory system. Here, we present research in which we stimulated guinea pigs with US and performed invasive extracellular recordings to identify the relationship between US and evoked neural activity. The stimuli consisted of simple unmodulated ultrasound waveforms, to identify the relationship between ultrasound intensity and neural activity, as well as modulated ultrasound waveforms, to investigate how encoding meaningful information manifests in the neural rate code. We also tested how the presence of the skull and ultrasound transducer placement affect the neural response to understand the role of the skull as a transmission pathway for ultrasound. We observed that unmodulated ultrasound primarily activates the high-frequency regions of the cochlea, and that at low levels of ultrasound the evoked activity is comparable to conversational sound levels in these regions. These results suggest that high-level ultrasound can induce wide activation of the auditory system, and potentially drive startle responses often thought of as direct activation of motor circuits. We also observed that removing the skull or placing the transducer closer to the target cochlea increases the overall evoked neural activity, suggesting that ultrasound activation of the auditory system differs from bone conduction in significant and meaningful ways. Modulating ultrasound with simple tones reliably activates the auditory system in a similar way to pure tones presented via traditional air conduction mechanisms particularly in cochlear regions below 20 kHz, even at low ultrasound pressures. When ultrasound is modulated with more complex waveforms, such as guinea pig vocalizations, the ICC responds in similar temporal patterns as when the vocalizations are presented in traditional ways. We developed generalized linear models (GLMs) to capture these neural dynamics and compared the spike rates when evoked via different modalities. Finally, our studies demonstrate different response patterns when the vocalizations were presented via bone conductor or ultrasound stimulation, further suggesting that ultrasound transducers differ from traditional bone conductors in the method they activate the cochlea, suggesting that a high frequency ultrasound hearing aid can provide therapeutic benefits that differ from traditional hearing aid devices. Further understanding on how high frequency ultrasound activates the auditory system can help clarify the perceptual properties of ultrasound as well as the mechanisms by which this technology interacts with the rest of the nervous system."],"dc:identifier.uri":["https://hdl.handle.net/11299/278801"],"dc:language.iso":["en"],"dc:subject":["Auditory System","Bone conduction","Electrophysiology","Hearing devices","Ultrasound"],"dc:title":["Investing the effects of body-coupled ultrasound on the auditory system for a novel hearing aid"],"dc:type":["Thesis or Dissertation"]},"updated_at":"2026-07-24T05:19:48Z"}