Comparative analysis of orbicularis oculi electromyogram and voice fundamental frequency variation in the context of acoustic startle response

This paper presents a comparison of two methods for measuring the acoustic startle response: orbicularis oculi (eyeblink) electromyogram (EMG), which is the conventional measure, and voice fundamental frequency (F₀) variations as a consequence of laryngeal muscle innervations. A comparative analysis of the two approaches was performed using statistical methods, as well as system identification modeling using ARX, ARMAX, Output Error and Box-Jenkins models. For this purpose, an experiment was designed in which fourteen participants sustained constant phonation and acoustic startle stimuli of varying parameters were delivered at random time points during the phonation. Physiological signals, including eyeblink EMG, were acquired in parallel to voice recording. The comparative analysis showed that by increasing intensity of acoustic stimulus, response peak amplitudes of both: F₀ variations and rectified and smoothed EMG responses increased as well. Therefore, voice F₀ may be useful for startle response analysis when eyeblink EMG measurement is unavailable or impractical.