Formby et al.: Integration Without Absolute Energy Cues 1285 Journal of Speech, Language, and Hearing Research • Vol. 45 • 1285–1296 • December 2002 • ©American Speech-Language-Hearing Association 1092-4388/02/4506-1285 C. Formby Division of Otolaryngology–HNS University of Maryland School of Medicine Baltimore M. G. Heinz* Speech and Hearing Sciences Program Massachusetts Institute of Technology Cambridge I. V. Aleksandrovsky** Division of Otolaryngology–HNS University of Maryland School of Medicine Baltimore Temporal Integration of Sinusoidal Increments in the Absence of Absolute Energy Cues Classical temporal integration (TI) is often viewed as a frequency-dependent, energy-based detection process. Detection thresholds for brief sinusoidal incre- ments in either a fixed-level or a random-level broadband pedestal are reported that refute this traditional perspective of TI. Instead, evidence is presented that indicates (a) detection of absolute energy is not necessary for the TI effect and (b) the frequency dependence of TI is consistent with variations across frequency in peripheral auditory tuning, rather than the integration process per se. When peripheral frequency selectivity is controlled, TI can be explained by a frequency- invariant integration process over at least the frequency range from 500 to 4000 Hz. This process is characterized by threshold improvements of 8–9 dB per decade increase in duration for increment durations between 10 and 300 ms. KEY WORDS: temporal integration, energy detection, increment detection, roving-level paradigm, masked detection I nvestigators have known for at least 125 years that auditory detec- tion for brief signals improves as signal duration is increased (Exner, 1876). A number of different theories have been proposed to explain this perceptual effect (see reviews by Eddins & Green, 1995; Viemeister & Plack, 1993). One of the most prominent is classical energy detection theory, which assumes that threshold sensitivity between approximately 10 and 300 ms depends on the absolute energy content of the sinusoidal signal (Green, Birdsall, & Tanner, 1957). This means that for a decade increase in signal duration, signal power must be reduced by 10 dB to maintain constant energy, and thus constant detection. For signal dura- tions longer than about 300 ms, detection varies relatively little (or much less) as the signal duration is prolonged. This characteristic time- dependent pattern of sensitivity for tonal signals is commonly termed temporal integration (TI). The TI effect implies that, to a first approxi- mation, the ear acts as an energy-storing device and that the integration process of summing the signal power to generate the necessary energy for detection is complete for signal durations exceeding roughly 300 ms. Thus, for durations between about 10 and 300 ms, TI for sinusoidal sig- nals has historically been modeled as an absolute, energy-based detec- tion process. Over the past decade, this classical view of TI has been challenged on several fronts (e.g., Eddins & Green, 1995; Formby, Heinz, * Currently affiliated with Johns Hopkins University, Baltimore, MD ** Currently affiliated with Florida Medical Center and Nova Southeastern University, Ft. Lauderdale, FL