Effects of stimulus rate and noise on speech-evoked auditory brainstem responses

Objective: To evaluate the effects of two auditory stressors, fast stimulus rate and/or addition of white noise, on auditory processing of speech in normal hearing subjects. Design: Speech-evoked auditory brainstem responses (ABR) were collected using a 300 ms formant-synthesized /a/ vowel presented in four conditions: slow stimulus rate of 1.6/s in quiet, fast stimulus rate of 3.1/s in quiet, slow stimulus rate of 1.6/s with continuous white noise, fast stimulus rate of 3.1/s with continuous white noise. Study sample: Twelve subjects (25 to 35 years old) with normal hearing thresholds. Results: A fast stimulus rate in quiet reduced amplitude response corresponding to F1 but not to F0. The addition of white noise at the slow stimulus rate reduced amplitude of wave V and response amplitude at F1 but increased response amplitude at F0. Changing from quiet-slow to noise-fast increased response amplitude at F0 by 2.9 dB (p