Norms for disproportionate loss in speech intelligibility

The audiometric records of 324 subjects with sensorineural hearing loss, presumed to be cochlear, were analyzed in order to develop norms for 'disproportionate loss' in speech intelligibility. From the scatterplot relating PB(max) to PTA₂ (average of HTLs at 1000, 2000 and 4000 Hz), and the scatterplot relating SSI(max) to PTA₁ (average of HTLs at 500, 1000, and 2000 Hz), linear boundaries were constructed encompassing approximately 98% of observed values. A speech intelligibility score (PB or SSI) may be considered 'disproportionately poor' if it falls below this empirically derived boundary.