Masking of the non-test ear in tone decay, Békésy audiometry, and SISI tests

Masking of the non-test ear is frequently required in tone decay, Békésy audiometry and SISI tests; without it, serious misdiagnoses can result. Methods are given for calculating the dial levels of masking noises to be delivered and the extent of possible cross-masking. The methods are subdivided according to whether the tests to be employed are fixed-frequency or sweep-frequency, and to whether masking function data are available from previous use of shadow masking. In difficult cases, careful preliminary shadow-masking procedures and subsequent use of fixed-frequency tests is recommended.