Derivation of frequency importance functions for the AzBio sentences

Although the AzBio test is well validated, has effective standardization data available, and is highly recommended for Cochlear Implant (CI) evaluation, no attempt has been made to derive a Frequency Importance Function (FIF) for its stimuli. This study derived FIFs for the AzBio sentence lists using listeners with normal hearing. Traditional procedures described in studies by Studebaker and Sherbecoe [(1991). J. Speech. Lang. Hear. Res. 34, 427-438] were applied for this purpose. Participants with normal hearing listened to a large number of AzBio sentences that were high- and low-pass filtered under speech-spectrum shaped noise at various signal-to-noise ratios. Frequency weights for the AzBio sentences were greatest in the 1.5 to 2 kHz frequency regions as is the case with other speech materials. A cross-procedure comparison was conducted between the traditional procedure [Studebaker and Sherbecoe (1991). J. Speech. Lang. Hear. Res. 34, 427-438] and the nonlinear optimization procedure [Kates (2013). J. Acoust. Soc. Am. 134, EL459-EL464]. Consecutive data analyses provided speech recognition scores for the AzBio sentences in relation to the Speech Intelligibility Index (SII). The findings of the authors provide empirically derived FIFs for the AzBio test that can be used for future studies. It is anticipated that the accuracy of predicting SIIs for CI patients will be improved when using these derived FIFs for the AzBio test.