Tympanometric gradient measured from normal preschool children.

Tympanometric gradient is a quantitative expression of the shape of a tympanogram in the vicinity of the peak. Previous work suggests that gradient measures may be diagnostically and prognostically useful in the assessment and management of middle ear disease. However, since almost all previous work on the subject was performed on tympanograms recorded in 'arbitrary compliance units' which are not comparable to the physical admittance units provided by currently available instrumentation, at this point the tympanometric gradient can only be viewed to be a potentially-useful clinical measure. In this investigation, eight tympanometric gradient measures were calculated from tympanograms obtained from normal preschool age children. The measures were evaluated on the basis of distribution characteristics, relation to static admittance, and effect of pump speed. One of the measures--the pressure interval defined by a 50% reduction in peak eardrum admittance--appears to be the procedure of choice. Measurements obtained from abnormal ears are needed to evaluate the clinical utility of this measurement.

Recognition masking-level differences for 10 CID W-1 spondaic words.

Psychometric functions for the S omicron N omicron and S pi N omicron conditions and masking level differences were obtained for a subgroup of 10 words having the largest masking-level differences of 36 CID W-1 spondaic words. The mean masking-level difference obtained from 36 young normal adults was 9.4 dB with a standard deviation of 1.2 dB. The smallest masking-level difference of 7.4 dB was suggested as the low cut-off for normalcy. A shorter version of the masking-level difference procedure was suggested for clinical implementation. The subgroup of 10 words may permit a wider separation between normal and abnormal performance, and thus may enhance the clinical utility of the masking-level difference task for speech recognition. Because the magnitude of the masking-level difference will vary with the materials and procedures used, each clinic must establish its own norms.