Validation of Count-the-Dots audiogram approaches to calculating speech intelligibility indices

Abstract

This study evaluates Count-the-Dots Audiogram approaches as a simplified clinically viable method to closely estimate the American National Standards Institute [ANSI (1997). S3.5-1997) Speech Intelligibility Index (SII)] standard in quiet environments. We compared audibility calculations and predicted intelligibility scores between Count-the-Dots methods and multiple ANSI [(1997). S3.5-1997)] SII variants, using eight frequency Band Importance Functions (BIF) for 14 776 audiograms from the National Health and Nutrition Examination Survey dataset. Results showed that Count-the-Dots methods closely approximate the ANSI [(1997). S3.5-1997)] SII model as long as the speech levels and the BIF used for calculations were equivalent between the two methods. This was true for audibility calculations and speech intelligibility predictions. However, deviations occurred at higher speech levels [≥65 dB sound pressure level (SPL)] because of differences in how masking is modeled. Count-the-Dots audiogram approaches offer a clinically viable, intuitive alternative for counseling purposes in quiet settings, particularly at natural speech levels (about 55 dB SPL). However, for speech-in-noise conditions, high-level speech, or aided speech inputs, the ANSI [(1997). S3.5-1997)] SII remains the preferred model because of its more detailed acoustic modeling.