Kahn D W, Tichy J
J Acoust Soc Am. 1986 Sep;80(3):815-27. doi: 10.1121/1.393957.
Measurements of steady-state sound pressure levels above the audience in large lecture halls show that the classical equation for predicting the sound pressure level is not accurate. The direct field above the seats was measured on a 1:10 scale model and was found to be dependent on the incidence angle and direction of sound propagation across the audience. The reverberant field above the seats in the model was calculated by subtracting the direct field from the measured total field and was found to be dependent on the magnitude and particularly on the placement of absorption. The decrease of sound pressure level versus distance in the total field depends on the angle (controlled by absorption placement) at which the strong reflections are incident upon the audience area. Sound pressure level decreases at a fairly constant rate with distance from the sound source in both the direct and reverberant field, and the decrease rate depends strongly on the absorption placement. The lowest rate of decay occurs when the side walls are absorptive, and both the ceiling and rear wall are reflective. These consequences are discussed with respect to prediction of speech intelligibility.
对大型讲堂观众席上方稳态声压级的测量表明，用于预测声压级的经典方程并不准确。在一个1:10比例模型上测量了座位上方的直达声场，发现其取决于入射角和声音穿过观众席的传播方向。通过从测量的总声场中减去直达声场来计算模型中座位上方的混响声场，发现其取决于吸声量，尤其取决于吸声材料的布置。总声场中声压级随距离的降低取决于强反射声入射到观众区域的角度（由吸声材料布置控制）。在直达声场和混响声场中，声压级均随着与声源距离的增加以相当恒定的速率降低，且降低速率很大程度上取决于吸声材料的布置。当侧壁为吸声材料，天花板和后壁为反射材料时，衰减率最低。针对语音清晰度的预测对这些结果进行了讨论。
