Speech audiometry: digitization effects and the non-equivalence of isophonemic word lists

Phonetically balanced word lists have many applications, including the field of audiometric testing, as equivalent test material. An experiment designed to assess the effects of digitizing parameters on speech intelligibility has shown, following detailed analysis, that the lists show a degree of non-equivalence. The reasons for this are explored and questions asked about the fundamental principles involved in describing speech forms. Other approaches to this kind of assessment are discussed.