Bone-conduction force values for the sensorineural acuity level (SAL) test.

The sensorineural acuity level (SAL) test has the advantages of eliminating the questions of when to mask and how much masking to use in audiometry, greater efficiency in assessing cochlear sensitivity than conventional bone-conduction (bc) testing, and fewer and less serious errors in measuring cochlear sensitivity. However, a major limitation of the SAL test is that norms are generally determined using the time-consuming real-ear calibration method. A more satisfactory procedure is to establish normative force levels using an artificial mastoid. Normal-hearing young adults (N:18) were tested with pure tones and with spondees, in the presence of bc white noise delivered to a Radioear B-70-AA vibrator and calibrated with a Bruel & Kjaer 4930 artificial mastoid. Force levels in db re 1 mu Newton found to produce a 30-db HTL in bc white noise were: 104, 94, 94, 94, and 100 for tones of .5, 1, 2, and 4 kc/s, and for spondees, in that order. Force levels for narrow bands of noise centered at .5, 1, 2, and 4 kc/s were 104, 84, 76, and 86 db in that order. Clinicians are cautioned to use these force values with reservation unless their bone vibrator, artificial mastoid, and noise spectra are similar to those used in the present study. If clinics choose to obtain their own baseline data, artificial mastoid measures can still serve as a convenient reference to monitor equipment stability. The use of the SAL is urged as part of a test battery for assessing the presence and degree of conductive pathology.