This research investigates the human observer's ability to discriminate difference in duration for noise bursts and gated sinusoids. Two observers compared two durationsTandT+ΔTin a two‐alternative forced‐choice procedure. The value ofTranged from 0.16 to 960 msec. For eachTthe value of ΔTfor 75% discrimination was determined. The results showed that for most of the range investigated ΔTwas proportional toT12. Performance was not affected by a change in bandwidth from 3500 to 200 Hz. Values of ΔTfor 75% correct did decrease, however, when the observers were given audible spectral cues from very short pulsed sinusoids. The theory best describing the results was the neural counter model proposed by Creelman [J. Acoust. Soc. Amer.34, 582–593 (1962)].