Adaptive measurement of speech intelligibility with the use of the maximum likelihood procedure

An adaptive maximum-likelihood procedure (MLP), typically used for threshold measurements in psychoacoustics, was adopted for the measurement of speech intelligibility, with the use of the modified rhyme test (MRT) [1]. The advantage of the MLP over the fixed step up-down adaptive procedures usually employed in adaptive speech intelligibility tests is that the MLP imposes no restrictions on the selection of the target percent-correct word score. An adaptive test based on the MLP permits quick estimation of the S/N ratio at any word score, pre-selected as an input parameter. Owing to its high efficiency, the MLP is a useful tool for rapid assessment of the S/N ratio of communication systems. As an example of such an application of the MLP–MRT adaptive test presented are preliminary measurements of speech intelligibility conducted on listeners wearing hearing protectors.