Abstract:
Sufficiently fast periodic amplitude or frequency variations of sounds may lead to roughness sensations with a negative effect on the perceived acoustic quality. That is a reason why roughness investigations gain much attention in sound quality research. Roughnesses of modulated synthesized sounds and technical noises are assessed by Japanese listeners in a classroom and in a laboratory experiment with a combined method of scaling and intermittent thinking aloud (ITA). Seventy-five short noises are presented in three consecutive blocks of 25 each, with long pauses between the blocks. The test subjects are asked to categorically assess the roughness of the sounds presented after they have been introduced to the concept of roughness by examples of typical rough sounds. After 25 noises are presented, the subjects are asked to write down what is going through their minds at that moment (ITA). At the end of the noise presentations the subjects answer an additional questionnaire concerning the sounds and the experimental situation. In the classroom experiment 202 students perform the difficult experimental tasks. Ten subjects repeat identical tasks in the laboratory when assessing roughness and pleasantness.