Package: SII 1.3.0

SII: Calculate ANSI/ASA S3.5-1997 (R2024) Speech Intelligibility Index

Calculates the American National Standards Institute (ANSI) S3.5-1997 Speech Intelligibility Index (SII) (ANSI, 1997), a standard method for computing the intelligibility of speech from acoustical measurements of speech, noise, and hearing thresholds. This package includes data frames corresponding to Tables 1 - 4 in the ANSI standard as well as functions utilizing these tables and user-provided hearing threshold and noise level measurements to compute the SII score. The methods implemented here extend the standard computations to allow calculation of SII when the measured frequencies do not match those required by the standard by applying interpolation. The package also includes a native C++ implementation of the 'AUDMOD' specific loudness model for impaired hearing (Bramslow, 2004), ported from the 'bramslow2004' implementation in the Auditory Modeling Toolbox (AMT), to calculate loudness in sones. It provides methods to predict aided SII under hearing aid prescriptive rationales, including Open-NL (Open Non-Linear), a theoretical optimization framework that uses a Nelder-Mead simplex search to maximize the SII (by default with the Johnson and Dillon (2011) desensitization correction), subject to loudness penalties and simulated Maximum Power Output (MPO) constraints. Further functions calculate real-ear insertion gains, estimate maximum power output (SSPL90), and prescribe dynamic range compression. Open-NL and the prescription functions are research tools for theoretical modeling and simulation; they have not been clinically validated and are not intended for fitting hearing aids to patients. Development of this package was originally funded by the Center for Bioscience Education and Technology (CBET) of the Rochester Institute of Technology (RIT).

Authors:Gregory R. Warnes [aut, cph], Mark Shaver [cre, aut]