For positions along the center aisle of a rectangular hall, the ratio of travel times of early reflections from the ceiling and walls is approximately equal to 2H/W, where H is the height and W is the width of the hall. This ratio was determined for 38 concert halls and opera houses and the results were compared with the subjective categories compiled in Beranek's extensive investigation [L. L. Beranek, Music, Acoustics and Architecture (John Wiley & Sons, Inc., New York, 1962)]. The correlation coefficient for 2H/W and a numerical scale of the subjective categories is 0.71. Thus it appears that this ratio, which determines the relative arrival times of early lateral and vertical reflections, accounts for a major portion of the subjective ratings. The importance of lateral versus vertical reflections has been substantiated by laboratory experiments conducted in an anechoic chamber, using delayed speech and music signals played through loudspeakers.