Methodological problems in the determination of homolateral stapedius reflex threshold.

Generally, a bilateral symmetry of the acoustic stapedius reflex is assumed. But a homolaterally higher sensitivity has been described. We examined 71 patients with complete unilateral deafness. With a TDH 39 headphone, stimuli of intensities up to 133 dB were conveyed to the deaf ear. A fairly accurate estimate of the normal homolateral threshold is obtained by correcting for the cross-hearing loss and by mathematical consideration of the relative probabilities of the positive and negative cases. Methodology-specific influences are discussed and a correction made for them. The homolateral reflex threshold is 9-14 dB lower than the contralateral reflex threshold.