Acoustical Properties of the Salt Lake Tabernacle

Abstract

Prof. Wallace Sabine's method of determining reverberation periods was used. Organ pipes in the tabernacle organ served as the source of sound. By opening and closing doors and windows the absorbing power of the building was found to be 630 open window units. The period of reverberation increased from 1.63 seconds for a note of 16 v.p.s. to a maximum of 5.21 seconds for 348 v.p.s. thence decreasing to 0.97 seconds for 8368 v.p.s. The constant of decay of sound, the mean free path, the paramoter k, and the volume of the building were determined by observing the variations produced in the reverberation by variations in the intensity of the sound. The intensity of the sound was determined throughout the building and expressed in terms of the intensity meter from the source. It was found to vary from 100 per cent at near stations to 4.2 per cent at remote distances. Articulation tests showed the percentage of syllables accurately received varied from 39 per cent for normal conversation voice to 59 per cent for preaching voice, to 80 per cent for electrically amplified voice. When the reverberation was reduced from 5 seconds for the empty building to 2.3 seconds when 3100 people were present good hearing increased from 52 per cent to 59 per cent for preaching voice in spite of presence of additional noises caused by audience.