Stability of Auditory Steady State Responses Over Time.

Area of Science:

• Neuroscience
• Audiology
• Signal Processing

Background:

• Auditory steady state responses (ASSRs) are crucial for objective hearing assessments.
• ASSRs are assumed to be stable due to periodic stimuli, but loudness adaptation is a known behavioral response.
• This study examines ASSR amplitude stability and its relation to loudness adaptation.

Purpose of the Study:

• To investigate the temporal stability of auditory steady state response (ASSR) amplitudes within recordings.
• To determine if loudness adaptation, a behavioral phenomenon, is reflected in ASSRs.
• To validate the use of ASSRs in clinical audiology.

Main Methods:

• ASSRs were recorded from 14 normal-hearing participants using specific modulated sinusoidal stimuli.
• Two analysis methods, Fast Fourier Transform and Kalman filtering, were employed to assess amplitude changes over 92-second recordings.
• Correlation analysis was performed between ASSR amplitudes and behavioral loudness adaptation ratings.

Main Results:

• ASSR amplitudes demonstrated overall stability, with a median change of -0.0001 μV/s.
• A statistically significant but very small decrease in amplitude over time was observed (-0.0002 μV/s).
• Correlations between ASSR amplitudes and behavioral loudness adaptation were significant but low to moderate (r=0.27-0.39).

Conclusions:

• The minor decrease in ASSR amplitude over short durations supports their clinical utility.
• No additional correction factors are necessary for objective hearing assessments using ASSRs.
• Loudness adaptation is unlikely to be significantly reflected in ASSRs due to the small amplitude changes observed.