Average Sound Absorption per Person at Octave Band Frequencies Between 125Hz And 4000Hz in an Enclosure

Abstract

The audience constitutes the major sound absorbent materials in most church auditoria and, non-inclusion of the sound absorbed by the audience in the determination of the optimum reverberation time from the design stage accounts for the problem of poor sound quality in such church auditoria. To address this problem, this research was carried out to provide designers with data on sound absorption by an individual at some octave band frequencies important for understanding speech. The work utilized the Sabine’s formula for Reverberation Time to determine the sound absorption per person at Octave band frequencies of 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz and 4000Hz.  Data which included the volume, sitting capacity of persons and reverberation time of eight (8) churches were obtained when the churches were occupied and when unoccupied.  These data gave the calculated average sound absorption per person of 0.29, 0.43, 0.51, 0.68, 0.71 and 0.73 at these octave band frequencies respectively, all showing that the average sound absorption by an individual increases with frequency within this octave band frequency range.

Key Words: Reverberation Time, Sound Absorption, Octave Band Frequency.