The NSMRL tri-word test of intelligibility (TTI)

Abstract

A version of Griffiths’s Diagnostic Articulation Test (DAT) using three-word items is described. The test is applicable where monosyllabic words or sentence lists are undesirable or inappropriate. Each word of an item is drawn from a separate set of five monosyllabic real words differing only in the initial or final element. For each item, subjects underline one word in each of the three sets of words for that item on the answer sheet. The test examines reception of 150 words in 7 min as compared with 50 words in 5 min by the usual single-word format and preserves, moreover, the effects of gross temporal distortions and masking that occur within and between words in consecutive discourse. Discrimination scores for the tri-word test of intelligibility (TTI) as compared with the Modified Rhyme Test (MRT) and the C. I. D. sentence lists all taped with the same talker were lower when tested in quiet and even relatively lower in noise. The multiple-choice closed-set response permits easy administration, scoring, and analysis of confusions; enunciation of three semantically unrelated words in coarticulatory succession preserves interword transitions while limiting the effects of memory and linguistic redundance. The use of the DAT lists permits a somewhat more detailed analysis of errors than use of the three-word formant with the MRT as proposed by Williams et al. (Aviat. Space and Environm. Med. 47, 154–158 (1976). The NSMRL TTI is proposed as a relatively ease of administration and scoring are desirable.