Applying a combined metric based on fluctuation characteristics to outline the impact of noises in the classrooms

In a companion paper by the same authors (N. Prodi and C. Visentin, "Revising fluctuation noise characteristics for describing the reception of speech in rooms with a combined metric", Proc. of INTERNOISE2013, Innsbruck 15-18 September 2013) a novel combined objective metric for assessing the role of noise fluctuations on word recognition in rooms was presented and discussed. The parameter is termed "speech fluctuation quality index" SFQI and includes both an indirect evaluation of the noise modulations on the signal plus noise combination and a loudness discrimination correction. The approach, matched to closed set DRT tests, allows to evaluate each noise separately and this feature is mostly relevant in classrooms, where the disturbances are of various nature and each has its own fluctuation attributes. In the present work it is shown how the SFQI is able to segregate the noises, and works when STI substantially fails. The pupils' performance is thus much better depicted especially when the "listening efficiency" subjective data are considered in the analysis. Applications of this objective/subjective approach will be fostered in other contexts too