The effects of stage absorption on reverberation times in opera house seating areas.

The effects of stage absorption on reverberation times in opera houses were investigated using computer simulations and scale model measurements. The reverberation time (RT) was measured in stalls seating with and without variable stage elements (e.g., fly curtains, side curtains, cycloramas, and stage sets). The absorption coefficients of the walls and ceiling of the stage houses were varied accordingly. It was found that variable stage elements have a significant influence on reverberation times in seating areas, particularly for a reverberant stage house, due to the low absorption of the walls and ceiling in the stage house. It was also found that the absorption coefficients of the walls and ceiling should be over 0.5 to avoid RT decreases of over 10% due to the absorption of the variable stage elements. In addition, coupled room effects were investigated both with and without variable stage elements and the results show that double slope was not found in the opera houses investigated in this study.

Effect of temporal decay on perception of heavy-weight floor impact sounds.

This study investigates the effect of temporal decay on perception of heavy-weight floor impact sounds through auditory experiments. Heavy-weight impact sounds were recorded in apartment buildings with a box-framed type reinforced concrete structure using a rubber ball. Temporal decay was quantified by using the decay rate (DR), defined as the sound pressure level (SPL) decrease per second [dB/s], and the distribution of DR for heavy-weight impact sounds was calculated. An auditory experiment was conducted in order to examine the just noticeable difference (JND) of DR, which was determined by the criteria of 75% correct answers by subjects. It was found that the JND of DR is around 11 dB/s. Based on the distribution and JND of DR, another experiment was conducted to investigate the effect of DR on annoyance perception of heavy-weight floor impact sounds in relation to the level differences. The results indicate that SPL and DR significantly influence annoyance perception; the scale value of annoyance increases with decreasing DR and increasing SPL. It was also found that the degree of satisfaction with regards to impact sounds can be improved by increasing DR, by controlling the sound field of the receiving room.

Subjective and objective evaluations of a scattered sound field in a scale model opera house.

Scattered sound fields in an opera house were objectively and subjectively evaluated through acoustical measurements in a 1:10 scale model and through auditory preference tests. Acoustical characteristics were measured in the stalls area with and without diffusers, both on the sidewalls close to the proscenium and in the soffit of the side balcony. Installed diffusers reduced the initial time delay gap and amplitude of the first reflected sound, and decreased sound pressure level (SPL), reverberation time (RT), and early decay time (EDT) at most seats due to the increased scattering and absorption. After diffuser installation, C(80) and 1-IACC(E3) increased at the front seats and decreased at the rear seats. Subjective evaluations showed that the preference of scattered sound fields correlates highly with loudness and reverberance. It was also found that EDT and SPL are dominant parameters describing subjective preference for scattered sounds in this experimental condition.