Speech intelligibility depends on which frequency bands matter for specific materials.

Evidence

The SII assumes that different frequency bands contribute different amounts to the ultimate ability to understand speech, and these differences are characterized via frequency importance functions. When a listener has a hearing loss in one of the more important bands, his perception of speech would be affected more than a listener who has a hearing loss in one of the less important bands. Different speech materials have different SII functions, and so one needs to know the testing materials as well as the degree and configuration of hearing loss to predict how much speech will be audible to a listener. The SII is convenient, and using the count-the-dot audiogram, one can quickly calculate and visualize the amount of audible speech information (e.g., Mueller & Killion, 1990). — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1690

Categorization

• DEFINE: Explains how the Speech Intelligibility Index weights frequency bands and how count-the-dot audiograms visualize audible speech.