Tawfik, S.,Sadek, I. and Wael, M., 1999
Objective:
The purpose of this study was to address the issues linking the Articulation Index (AI) to the process of predicting hearing aid performance relative to the Arabic speech perception tests.
Design:
Thirty patients (ten 20- to <30-yr-olds; eight 30- to 40-yr-olds; twelve 40- to <50-yr-olds) with bilateral flat symmetrical sensorineural hearing loss (better ear average four-frequency hearing loss = 54.5 dB HL;range: moderate to moderately severe) were included in the study. They all were required to have almost fully developed speech and language. The selected hearing aid (Philips S 47 I) was fitted monaurally to the better ear and adjusted according to the NAL-R formula by the help of a probe tube set. Testing was completed with the patient seated in a conventional audiologic test suite with the non-test-ear plugged. Functional gain was measured using warble tones delivered through a loudspeaker located at 0 azimuth. Speech perception tests' materials were then presented at a fixed signal level (60 dB HL). SNR was +10 (noise was delivered from a back loudspeaker at a fixed level; 50 dB HL) for speech in noise tests. Finally, the AI was calculated according to the unweighted formula of Pavlovic (1988).
Results:
Both the degree and relative duration of hearing loss were negatively correlated with the speech perception tests' scores . However , significant effects of the degree of hearing loss on the speech recognition abilities were revealed by the analysis of variance. The relative ability of the AI to predict hearing aid performance was exhibited by the stepwise regression procedure. The AI was less successful in the prediction of the speech recognition in adverse listening situations.
Conclusions:
This investigation revealed that the degree of hearing loss had a more prominent effect on the speech recognition abilities than the relative duration of hearing loss . The AI was a relative rather than an absolute predictor of speech intelligibility in aided conditions .