STI and RASTI

STI and RASTI, the original versions, which are based on weighted sums of modulation transfer function (MTF) values [T. Houtgast and H.J.M. Steeneken, "A review of the MTF concept in room acoustics and its use for estimating speech intelligibility in auditoria," J. Acoust. Soc. Am., vol. 77, pp. 1069-1077 (1985), and IEC-60268-16 1.ed].

RASTI is included in WinMLS only for historic reasons. It was developed to reduce measurement time for room acoustic use. Using WinMLS, the measurement time will be the same for STI and RASTI. STI is the better measure, and should therefore be the choice of preference between the two unless the RASTI value is required.