Influence of classroom acoustics on student presentations

Teachers are better speakers when compared to students with oracy built into their professional experience over a period of time. Students' perception and judgement of teachers' speech intelligibility has been reported abundantly in literature. However, teachers' perception of students' speech intelligibility has been rarely studied in the context of classroom acoustics. Graduate students deliver presentations and talks regularly in classrooms and are assessed and also graded based on their communication skills and delivery. Vowel space area (VSA) is an objective metric to evaluate the talker speech intelligibility and articulation. From recorded presentations, VSA has been evaluated from the first two formant frequencies, F1 and F2 measured from speech waveforms of words containing the corner vowels. VSA analysis was done in two different classroom acoustical conditions. Acoustical conditions were characterized for the two classrooms by measuring octave band reverberation times and background noise levels. This was used to evaluate the room average useful-to-detrimental energy ratio (U50), an objective metric to evaluate intelligibility in rooms for speech. Influence of classroom acoustical characteristics on students' speech intelligibility was studied by comparing VSA's for all student talkers and the classroom average U50 metric. The results indicate that teachers' judgment of students' speech and delivery could very well be influenced by classroom acoustical conditions.