Magnitude of the acoustic reflex for either homophasic (0 degrees) or antiphasic (180 degrees) binaural activating signals presented in a background of noise.

The threshold of the acoustic reflex (TAR) and the magnitude of middle-ear muscle response were measured for a homophasic (0 degrees) and an antiphasic (183 degrees) 550-Hz tone in a background of in-phase noise. Signal-to-noise ratio ranged from - 20 dB to 5 dB. Whereas previously reported data shows an effect of phase on the percept of loudness, no evidence of a phase effect was measured for acoustic-reflex responses. These results are interpreted as evidence against a relation between loudness and acoustic reflex for binaurally presented signals.