Rate integration in click‐evoked acoustic reflex thresholds

Abstract

Effects of click repetition rates on acoustic reflex thresholds were investigated in 11 female subjects (total 22 ears) within the age‐range of 20 to 26 years. Acoustic reflexes were elicited in response to ipsilateral condensation clicks of 100‐μs duration at repetition rates of 50, 100, 150, 200, 250, and 300/s. The probe tone frequency was 226 Hz and the intensity was 85 dB SPL. Acoustic reflex thresholds were defined at the lowest intensity at which a minimum of 0.02‐ml change in admittance was evident on at least two of three trials. The thresholds became significantly better with increase in the repetition rates. The average threshold advantage for the 300/s‐click rate over the 50/s rate was 22.5 dB and that of the 100/s rate over the 50/s rate was 12.5 dB. Although such advantage with increase in stimulus repetition rates has been most commonly referred to as temporal integration, a more appropriate term for this phenomenon may be rate integration. Since the firing rates of auditory neurons are known to increase with increase in stimulus intensity, it is conceivable that stimuli presented at higher repetition rates are perceived as being louder. [Work supported by Bloomsburg University Grants for Research and Creative Projects and State System of Higher Education Minority Faculty Development Fund, Pennsylvania.]