Using listening effort assessment in the acoustical design of rooms for speech

Abstract

This study addresses the issue of an enhanced acoustical design of rooms for speech, which besides targeting high speech intelligibility also ensures minimal effort in speech reception. Speech-in-noise tests in the Italian language were proposed to normal-hearing young adults, both in situ, within an existing university classroom, and via headphones, using auralized signals obtained from acoustic simulations of the same environment. Later, auralization was used to investigate the effect of realistic modifications to the room acoustics (acoustical treatment of a wall, change of the room size) by altering the virtual model of the classroom. The speech reception performance was characterized by using both the number of words correctly recognized (speech intelligibility, IS) and two estimates of listening effort: the behavioral measure of response time (RT) and a subjective judgement on a rating scale (LE). Firstly, the correspondence between the IS, RT and LE results in situ and in auralized conditions was considered and discussed. Then, the effectiveness of the three metrics in outlining the effect of the acoustic changes of the room was analyzed. The results showed that there were no differences between the compared acoustic conditions in terms of IS. The effects of the characteristics of the room acoustics were instead discriminated when RT and LE were considered, with the greatest number of significant differences observed by using RT. Using RT therefore seems to be an effective and promising strategy to better discern the effects of the room acoustics and to enhance the acoustical design of rooms for speech.

Classroom acoustics: Listening problems in children

“…The design of places in which it is important to ensure good speech and listening conditions should include a measure of objective acoustical parameters, such as RT and STI (as a measure for speech transmission quality), and a measure of speech reception performance, for example, through the speech intelligibility score. 37 In this respect, regarding Italy, the new Italian standard on acoustics for schools introduces significant improvements. All the parameters linked to the quality of listening were evaluated, and the attention was focused on specific predicting and practical verification methods.…”

“…On the whole, children performed worse in noisy condition, and greater response time values were found compared with those achieved in quiet condition. Visentin et al 37 analysed two behavioural parameters involved in listening effort: the measure of response time and a subjective judgement on a rating scale (LE). The response time was found to be a more sensitive measure in order to analyse the effects of the different listening conditions.…”

“…The response time evaluation can, therefore, provide useful information which needs to be assessed in discerning the effects of the room acoustics and improving the acoustical design of rooms for speech. 37 It has been shown that also dysphonic teachers, speakers with a weak voice, fast-talking or low fluency, may imply higher level of children listening effort and cognitive load, but only few countries provide training courses on the use of voice for teachers. 38 There are also several factors which can make the difficulty in listening and understanding in noisy environments an even greater problem, for certain categories of children.…”

Speech intelligibility and listening effort in university classrooms for native and non-native Italian listeners

“…Thus, the decrease in intelligibility in the present case can be ascribed to a longer reverberation time ( T = 0.83 s) or to the type of material used here, whose lack of context and syntax may result in a more difficult task. However, the type of presentation should not bias the data, as demonstrated in Visentin et al 23…”

“…This study was part of a broader research program conceived to enhance the acoustical design of rooms for speech, which, besides targeting high SI, also ensures minimal processing effort in speech perception (see Visentin et al 23 for an overview). In this study, the results of the experimental session consisting of listening tests inside a university classroom are considered.…”