The same reverberation time in two identical rooms does not necessarily mean the same levels of speech clarity and sound levels when we look at impact of different ceiling and wall absorbers

摘要

It is common to only use Reverberation Time (RT) for setting the acoustic conditions in a classroom for teaching and learning activities. To calculate the RT in rooms with ceiling absorption is common but this data can also be misleading. Indeed, we measured the same RT values in two identical rooms with different acoustic treatment, even though the calculations predicted significant differences and interestingly the rooms are also be perceive quite differently in reality. Assuming that the user perceptions are valid, the measured RT data alone leaves us in the dark when seeking to explain the difference in human user perception. Measuring additional room acoustic parameters such as speech clarity and the difference in sound levels, identifies other differences between the two rooms with the same RT and points to why only one of the two rooms seems fit for purpose as a group activity room. We will discuss how to achieve acoustic comfort in classrooms; low RT, low sound levels and high speech clarity. In addition to commonly accepted low RT values we will discuss recommended objective values for good Speech Clarity to support good speech communication activities in typical teaching and learning rooms in real life situations.