A series of experiments was conducted to evaluate the effects of certain procedural variables on SAL audiometry and to compare SAL and BC threshold hearing levels in subjects with both conductive and sensori-neural hearing loss.

Procedural variables included the force of application of the bone vibrator, the duration of bone-conducted noise exposure, the direction of frequency change of the Bekesy audiometer, the linearity of masking functions for air-conducted tones in bone-conducted noise, the masking level difference phenomenon, the acoustic reflex, and the effect of occlusion.

SAL and BC threshold hearing levels were then compared in 10 subjects with asymmetrical conductive loss and 10 subjects with asymmetrical sensori-neural loss. In all subjects the presence of a severe or total sensori-neural loss on the non-test ear permitted the valid measurement of bone-conduction thresholds without the use of masking on the non-test ear.