Effects of High-Intensity Airborne Ultrasound Exposure on Behavioural and Electrophysiological Measures of Auditory Function

Abstract

Regulations on safe ultrasound exposure limits are based on a very limited number of studies, which have only considered audiometric threshold shifts as indicators of hearing deficits. The purpose of the current study was to assess the effects of exposure to high-intensity ultrasound on a range of measures of hearing function, which included audiometric thresholds, as well as subclinical measures of hearing deficits: speech-in-noise understanding, supra-threshold auditory brainstem response wave I amplitude and latency, and frequency following response levels to amplitude modulated (AM) tones. Changes in these measures were assessed before and after exposure of the left ear to high-intensity ultrasound in a group of nine young listeners. These changes were compared to those observed in a control group of nine young listeners. Exposure consisted in the presentation of a 40-kHz AM tone at levels of 105, 110, 115, and 120 dB SPL for 10 minutes at each level, plus an exposure to a 40-kHz unmodulated tone during an ultrasound detection task, for a total duration of 50 seconds. None of the measures of hearing function was found to change significantly more for the left compared to the right ear, for participants of the exposure group compared to control participants. Electroencephalographic recordings obtained during exposure to the AM tone did not show significant phase-locked activity at the modulation frequency or at low-frequency subharmonics of the ultrasound tone. One out of nine participants was able to perform the ultrasound detection task above chance level, although due to limitations of the experimental setup the mechanism by which she could detect the presentation of the tone remains unclear.

Effects of age on electrophysiological measures of cochlear synaptopathy in humans

“…Log wave amplitude was used as the dependent variable ( Bramhall, Konrad-Martin, McMillan, Griest, 2017 , Bramhall, McMillan, Gallun, Konrad-Martin, 2019 , Carcagno, Di Battista, Plack, 2019 ). Wave I and wave V amplitudes were modeled jointly.…”

A Survey of Mid-Air Ultrasound Haptics and Its Applications

“…A further study into the effects of 40 kHz ultrasound on human hearing [134] found no evidence of a threshold shift indicative of potential hearing loss. They also found no evidence of brain activity (through EEG) in response to the ultrasound frequency or its lower harmonics.…”

“…Unlike audible sound, extreme levels of ultrasound would not cause noticeable discomfort that warns the user that their hearing is at risk. The highest pressure in the sound field is within the focal point(s), which may be in excess of 140 dB [130], [131], [134]. This pressure is highly localized, attenuating away from the focal point(s).…”

Generating Airborne Ultrasonic Amplitude Patterns Using an Open Hardware Phased Array

“…Ultraleap (Bristol, UK) is a company that commercializes ultrasonic phased arrays for haptic applications related to automotive [31], digital signage [32], and AR/VR [33] applications. The company has also been exploring the effects on humans of high intensity ultrasound exposure [34] and has been releasing multiple prototypes that explore optimized array designs [35,36]. For example, transducer array in a Fibonacci spiral arrangement can suppress unwanted secondary focal points [37].…”