Recently, Klein-Hennig et al. (J Acoust Soc Am 129:3856-3872, 2011) suggested a design for envelope waveforms that allows for independent setting of the duration of the four segments of an envelope cycle - pause, attack, sustain, and decay. These authors conducted psychoacoustic experiments to determine the threshold interaural time differences (ITDs) for different waveforms and revealed that a steep attack flank and at least 4 ms of pause duration prior to the attack are optimal for discrimination performance, whilst sustained and decay durations were of only minor influence. The current study tests the sharpness of rate-ITD-functions recorded in the inferior colliculus of guinea pigs in response to a similar set of waveforms, examining their relationship to the psychoacoustic data. Particular focus is applied to temporally asymmetric envelope waveforms: a long 15-ms attack and a short 1.5-ms decay envelope and the temporally inverted envelope with a short 1.5-ms attack and a long 15-ms decay.