Title

The use of the acoustic stapedial reflex as an indicator of high level noise exposure

Presentation Type

Poster

Abstract

The middle ear primarily provides an impedance matching of air-born sounds to the fluid medium of the inner ear by providing an amplification factor. It also acts as a system to protect the inner from loud sounds by invoking the action of the stapedius muscle. The stapedius muscle is a middle ear muscle that is part of the stapedius reflex. Whenever a sound reaches a level between 75-85 dB the stapedius muscle contracts with minimal latency (<1 msec) between the onset of the sound stimulus and the stapedial response. Both stapedius muscles will contract when a single ear is stimulated. Previous investigations of the stapedius reflex have always used pure tones or broadband noise as the source stimulus. Recording the reflex in the contralateral ear is readily accomplished by measuring the amplitude changes of a probe tone in that ear. This research has implemented a digital means for detecting the amplitude modulation of the probe tone to stimuli in the opposite ear. The very novel feature of this research is to measure the contraction of the stapedius muscle using a digital amplitude demodulation technique as a function of a varying stimulus. The stimulus in for this research was a popular music song played through an iPod. Subjects passively listened while recordings of stapedius contractions were obtained. Measures of the duration of the stapedius contraction and time histograms were obtained and will be discussed.

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Apr 13th, 3:00 PM Apr 13th, 4:00 PM

The use of the acoustic stapedial reflex as an indicator of high level noise exposure

UC Ballroom

The middle ear primarily provides an impedance matching of air-born sounds to the fluid medium of the inner ear by providing an amplification factor. It also acts as a system to protect the inner from loud sounds by invoking the action of the stapedius muscle. The stapedius muscle is a middle ear muscle that is part of the stapedius reflex. Whenever a sound reaches a level between 75-85 dB the stapedius muscle contracts with minimal latency (<1 >msec) between the onset of the sound stimulus and the stapedial response. Both stapedius muscles will contract when a single ear is stimulated. Previous investigations of the stapedius reflex have always used pure tones or broadband noise as the source stimulus. Recording the reflex in the contralateral ear is readily accomplished by measuring the amplitude changes of a probe tone in that ear. This research has implemented a digital means for detecting the amplitude modulation of the probe tone to stimuli in the opposite ear. The very novel feature of this research is to measure the contraction of the stapedius muscle using a digital amplitude demodulation technique as a function of a varying stimulus. The stimulus in for this research was a popular music song played through an iPod. Subjects passively listened while recordings of stapedius contractions were obtained. Measures of the duration of the stapedius contraction and time histograms were obtained and will be discussed.