Transient response methods have been used for studying and evaluating loudspeakers at the Armour Research Laboratory since 1945. Other distortions, such as intermodulation, were found to give poor correlation with results from listening tests. The most convenient method for studying the transients has been to introduce an interrupted audio signal of varying frequency into the voice coil, pick up the effect in the sound field of the loudspeaker with a transient-free microphone, and connect this to an oscillograph for observation. Some of the techniques developed are similar to those described by Shorter. A Massa M-101 measurement standard microphone with resonant frequency above 20 kilocycles was found to be very suitable for this work. The use of a good anechoic room is also essential, since some of the pressure decay curves are similar to the reverberation decay of a room. An interruption rate of 20 per second was found to be convenient. Measurements with this experimental arrangement have shown that loudspeaker decay time (to 1/e) are often longer than 0.01 second. Since the system is three dimensional involving complicated resonances of the loudspeaker radiating elements, the on-transient is different from, and cannot in general be correlated with, the off-transient. The paper will be illustrated by several slides showing some of these phenomena and a short moving picture reel will be shown of the transients that occur in several types of loudspeakers as the frequency is varied. The chief psychological effect which can be correlated with the transient effects is the “cleanness” of response of the speaker. It should be emphasized that these effects are only one of the criteria of evaluation of a loud-speaker. Some other methods of evaluating speakers will be given in another paper.