Lance Nizami

Learn More
Internal noise is often inferred from the difference between observed performance and optimum performance in detection and discrimination tasks. It can be measured directly in some cases by observing the extent to which a change in external variability impacts performance. In the studies reported here, external variability was added to an intensity(More)
Detection thresholds were gathered for a 2 kHz Gaussian-shaped probe (standard deviation = 0.5 ms), centered at intervals of as little as half a millisecond over 0-30 ms following a 200 ms, 97 dB SPL, 2 kHz tone. Surprisingly, there were small, sudden rises and falls superimposed on each subject's generally smooth recovery. Even more obvious were(More)
Dynamic range is one of four attributes typically assigned to the plot of firing rate vs. stimulus level of an auditory primary afferent. Dynamic range is generally understood to be the contiguous range of sound-pressure-level over which the neuron can indicate some small level change. Typically, however, dynamic range has been quantified as the width in(More)
K.H. Norwich et al. used Shannon Information Theory to derive their Entropy Theory of Perception (1975-present). The Entropy Theory produces the Entropy Equation, which relates the strength of sensation (represented by magnitude estimates) to the intensity of the sensory stimulus. At “high” intensities, the relation is approximately logarithmic, which(More)
Shortening the duration of a Gaussian-shaped 2-kHz tone-pip causes the intensity-difference limen (DL) to depart from the "near-miss to Weber's law" and swell into a mid-level hump [Nizami et al., J. Acoust. Soc. Am. 110, 2505-2515 (2001)]. For some subjects the size of this hump approaches or exceeds the size reported for longer tones under forward(More)
Psychometric functions (PFs) for forward-masked tones were obtained for conditions in which signal level was varied to estimate threshold at several masker levels (variable-signal condition), and in which masker level was varied to estimate threshold at several signal levels (variable-masker condition). The changes in PF slope across combinations of masker(More)
The Entropy Theory of Perception of Professor K.H. Norwich and various collaborators spans 1975 to 2010. Thirty-five years is a surprisingly long publication life for a mathematical model of perception. Its longevity is no doubt related to its unusual ability to provide derivations, from pure theory, of a large cadre of well-established empirical relations(More)
The classical model of forward masking postulates that the detection threshold for a tone probe that follows a stimulus of similar frequency content is elevated relative to the quiet threshold because the probe must evoke a just-detectable increment in a decaying postmasker sensation. That postmasker decay is charted by probe-detection thresholds if the(More)
Detection thresholds were obtained for Gaussian-shaped tone-pips of 1, 2, 3, or 4 periods duration for 20 frequencies spanning 50-3,000 Hz, in quiet, and in high-pass noise, for a single exceptionally patient and experienced listener. Thresholds were fitted by straight lines in decibels SPL versus the logarithm of duration. Slopes fell into 3 distinct(More)