Distortion of averaged post-auricular muscle responses due to system bandwidth limits

Substantially different waveform details have been reported in various studies of the post-auricular muscle (PAM) response. By examining the high frequency limits of the pass-bands used to record the response it would appear that the system bandwidth limits have affected the waveform. Recordings were made using a very wide bandwidth, and were used to obtain power spectra of these PAM responses. These determined the minimum bandwidth requirements to avoid distortion of the waveform. It seems clear that a substantial proportion of the differences reported have been due to the use of a recording bandwidth which has distorted the response.