Intelligibility measurements in speech disorders: a critical review of the literature.
BACKGROUND
the reduction in speech intelligibility is considered one of the main characteristics of individuals with speech disorders, and is an important issue for clinical and research investigation. In spite of its relevance, the literature does not present a consensus on how to measure speech intelligibility. Besides the diversity of existent methods, another important issue refers to the influence of certain variables on these measurements and, consequently, on the interpretation of the results.


OBJECTIVE
to investigate evidence on the agreement between speech intelligibility measurements, obtained through different methods, used in the assessment of speech disorders, and to identify the effect of variables related to assessment procedures or to the listener. A critical review of articles indexed in the databases Medline, Web of Science, Lilacs and Scielo, until October 2007, was carried out. The key-word used to perform the search was speech intelligibility.


CONCLUSIONS
there was no evidence of agreement between the speech intelligibility measurements obtained through different methods in the investigated literature. This fact limits the comparison between clinic and research results on speech intelligibility of individuals with speech disorders. Besides that, it was observed that some variables can interfere in these measurements, such as: type of task and speech stimulus, signal presentation mode, type of required answer and listener's experience with the speaker. These must be considered when interpreting the results of speech intelligibility tests.
Barreto
Simone dos Santos
Sdos S
Universidade Federal de São Paulo, São Paulo, Brasil. simone_barret@hotmail.com
Ortiz
Karin Zazo
KZ
D000161:Acoustic Stimulation; D006801:Humans; D010700:Phonetics; D013060:Speech / Q000502:physiology*; D013064:Speech Disorders / Q000503:physiopathology*; D013065:Speech Intelligibility / Q000502:physiology*; D013067:Speech Perception; D013068:Speech Production Measurement / Q000379:methods*; D013647:Task Performance and Analysis