Clarity & Strength in non-diffuse fields: comparison with diffuse field models
Invited paper
Apex Acoustics Ltd
Tuesday 2 june, 2015, 09:20 - 09:40
0.9 Athens (118)
Abstract:
Clarity, C50, and the useful to detrimental ratio, U50, have been proposed by Pelegrin
et al in models for determining room requirements that meet both listeners’ and
talkers’ needs in rooms for speech, such as classrooms. The models are based on
diffuse field assumptions; however, it is well known that rooms where the majority of
absorption is on the ceiling exhibit reverberation times that can significantly exceed
values that are calculated assuming diffuse field conditions.
Preliminary measurements in rooms with adverse acoustic conditions suggest that
excessive reverberation times do not necessarily imply that measured values of Clarity
and Strength are reduced from those calculated assuming diffuse field conditions.
Hence it may be considered that the quantity of absorption in the room is more
important than the measured reverberation time in determining the room response in
terms of Clarity and Strength. Thus while it is still important to limit
reverberation, small exceedences of reverberation time criteria may not be detrimental
to achieving the control of reverberant noise and Clarity in practice.