William D. Voiers
Dynastat, Inc., P.O. Box 388, Eureka Springs, AR 72632
In one form or another, the diagnostic rhyme test (DRT) has been in use for 30 years. This paper describes the latest version of the DRT, DRT-V, and two other diagnostic intelligibility tests based on the same principles and having the same general format as the DRT. These are the diagnostic medial consonant test (DMCT) and a new version of the diagnostic alliteration test (DALT-II). All three tests use the two-alternative, forced-choice paradigm to measure the discriminability of six distinctive features in consonant phonemes. They differ in the position of the equivocal phoneme, which, respectively, occurs initially, intervocalically, and terminally. In all three tests, vowel environment is systematically varied, and the discriminability of each critical feature is tested under systematically varied conditions of other, noncritical, features in the equivocal phoneme. These design characteristics provide a diversity of diagnostic scoring options. Comparative results are presented for selected types of speech degradation.