[Stopping criteria for averaging the multiple auditory steady-state response].

INTRODUCTION AND OBJECTIVES The aim of this study was to examine the efficiency of the averaging technique for estimating multiple auditory steady state responses in normal hearing subjects and to provide quantifiable stopping criteria at near-threshold intensities. METHODS Multiple amplitude-modulated (89-115 Hz) tones (500, 1,000, 2,000 and 4,000 Hz) were simultaneously presented to both ears at a fixed intensity of 40 dB HL. A total of 128 data epochs were averaged (23.9 minutes). RESULTS The results showed that "classic" ensemble averaging, although accurate and time-efficient in most cases, could not extract all near-threshold MSSR from noise, even after recording a considerable number of sweeps. The present study also proposed a different approach to evaluate the background noise based on evaluating the mean of the variance close to the signal. CONCLUSIONS The study proposed quantitative parameters to establish stopping criteria during auditory steady-state recordings.