The National Acoustic Laboratories' (NAL) CDs of speech and noise for hearing aid evaluation: Normative data and potential applications

This paper describes the speech and noise material on a new set of three CDs that is considered very suitable for hearing assessment and fine-tuning of hearing aids in audiological clinics. The material includes continuous discourses, various background noises, and three different speech test materials (BKB sentence test, four SPIN sentence lists, and Vowel-Consonant-Vowel (VCVs) nonsense syllables). All speech samples are recorded using native speakers of Australian English. Normative data in the form of the central part of performance-intensity functions are presented for the BKB sentences in babble-noise and for intelligibility rating of continuous discourse in nine background noises together with list-equivalence data for the BKB test. For each test, the critical difference that needs to be exceeded to obtain significantly different results is also presented. Applications for the material with respect to candidacy and hearing aid fine-tuning are discussed.