Some experiments are performed to test the influence of rise time on loudness of a 750-cps sinusoid and a broad-band noise. Rise times, defined for a 50-dB exponential variation in sound pressure level, were applied in the interval 0.025–1.6 sec. Maximum sound pressure level was 70–100 dB with duration 0.6 and 1.3 sec. A “paired comparison” method was used, and a decrease in loudness corresponding to approximately 3 dB in sound-pressure level was found for the broad-band noise. A smaller change was found for the 750-cps sinusoid.