Abstract: Based on the results of the impulse measurement, using electric spark as a sound source, and the subjective evaluation of the acoustical quality of ten halls, this paper has investigated some relations between the echo diagrams and the loudness, the intelligibility, and the fullness.
The informations contained in the echo diagrams can be expressed in three values-"a", "b" and "c", and it has been found that the value "a" is related with the fullness, and the value "b" with the loudness and the intelligibility.The value "c" indicates the relative energy density of the reflective sounds occurring within a certain time interval, and it depends on the dimensions and the shape of the hall.
This paper has also investigated the distribution of the value "c" in the halls of different dimensions and shapes, discussed its satisfactory distribution for good acoustical quality, and made suggestions for the hall design.