Anders Kjellberg

Poor Listening Conditions Impair Memory for Intelligible Lectures: Implications for Acoustic Classroom Standards

This paper reports two experiments on the effects of degraded speech signals on memory for spoken lectures. Experiment 1 showed that broadband noise impairs university students memory for a spoken lecture, even though the participants heard what was said. Experiment 2 showed that reverberation has detrimental effects to school adolescents memory for spoken lectures, similar to broadband noise. The results suggest that poor listening conditions (resulting from background noise and/or long reverberation time) impair memory and learning, even if the conditions allow the listeners to hear what is said. Since the goal for students and pupils attending to lectures is to remember the lecture rather than just hearing what is said, the results presented here indicate that standards for acceptable signal-to-noise ratios and reverberation times in buildings designed for learning should consider the distinction between speech intelligibility and memory. Standards should be based on memory criteria instead of intelligibility criteria.

Long Reverberation Time Decreases Recall of Spoken Information

The aim of the study was to explore if a long reverberation time has the same effect on recall of spoken words as background noise was shown to have in a previous study. A further aim was to study the influence of working memory capacity on performance in these conditions. Thirty-two subjects performed a word recall and a sentence recognition test. They repeated each word to ensure correct identification. A reading span test measured their working memory capacity. Performance of the word recall task was impaired by the long reverberation time. The effect was most evident in the primacy part of the word list. No correlation was found between reading span score and recall performance.