Loudness and the acoustic reflex: normal-hearing listeners.

The relationships among most comfortable listening level (MCL), loudness discomfort level, and the acoustic reflex to speech were studied on normal-hearing listeners using earphones and sound field test conditions. Recorded sentence materials were presented monaurally in quiet and, in the sound field, in the presence of 55 dB SPL cafeteria noise. The results indicate the MCL in the quiet sound field at approximately 70 dB SPL with the acoustic reflex occurring at 16 dB higher intensity. The earphone MCL was 7 dB lower than in the sound field, a finding that may reflect a real reverse in usual earphone/sound field results or simply calibration factors particular to the speakers and test room used in this study. The AR to speech seems to occur at approximately equal intensities between the MCL and LDL tested in quiet. The MCL is elevated by noise whereas the acoustic reflex remains at a constant level, indicating that no absolute relationship exists between loudness and the AR.