A computational model for the lateralization of binaural stimuli, motivated by recent physiological findings in the literature and psychoacoustic data is presented. The model is based on the evaluation of the interaural phase difference (IPD). In the model, IPDs are separately assessed for the stimulus’ fine-structure and envelope. Psychoacoustic measurements were conducted and compared to mode...

The purpose of this investigation was to study the impact of spectral shape and content on thresholds of discomfort (TD) for listeners with normal hearing and listeners with hearing loss. Secondary to that purpose was to quantify binaural summation at high intensities across complex stimulus conditions for both groups of listeners. Forty subjects (20 with normal hearing, 20 with hearing loss) p...

The octave or Deutsch illusion occurs when two tones, separated by about one octave, are presented simultaneously but alternating between ears, such that when the low tone is presented to the left ear the high tone is presented to the right ear and vice versa. Most subjects hear a single tone that alternates both between ears and in pitch; i.e., they hear a low pitched tone in one ear alternati...

Research has shown that if two frequencies differing in 30Hz or less are presented in each ear, the brain will process these frequencies as an entirely separate third tone. This third frequency, or binaural beat, can stimulate production of brain waves if created in the correct frequency range. This study recruited 38 participants to determine if binaural beats in the beta range can increase at...

Recent magnetoencephalography (MEG) and functional magnetic resonance imaging studies of human auditory cortex are pointing to brain areas on lateral Heschl's gyrus as the 'pitch-processing center'. Here we describe results of a combined MEG-psychophysical study designed to investigate the timing of the formation of the percept of pitch and the generality of the hypothesized 'pitch-center'. We ...

Human listeners are sensitive to interaural time differences (ITDs) in the envelopes of sounds, which can serve as a cue for sound localization. Many high-frequency neurons in the mammalian inferior colliculus (IC) are sensitive to envelope-ITDs of sinusoidally amplitude-modulated (SAM) sounds. Typically, envelope-ITD-sensitive IC neurons exhibit either peak-type sensitivity, discharging maxima...

Neurons in the medial superior olive (MSO) are thought to encode interaural time differences (ITDs), the main binaural cues used for localizing low-frequency sounds in the horizontal plane. The underlying mechanism is supposed to rely on a coincidence of excitatory inputs from the two ears that are phase-locked to either the stimulus frequency or the stimulus envelope. Extracellular recordings ...

Human listeners, and other animals too, use interaural time differences (ITD) to localize sounds. If the sounds are pure tones, a simple frequency factor relates the ITD to the interaural phase difference (IPD), for which there are known iso-IPD boundaries, 90°, 180°… defining regions of spatial perception. In this article, iso-IPD boundaries for humans are translated into azimuths using a sphe...

The Mongolian gerbil (Meriones unguiculatus) has become a key species in investigations of the neural processing of sound localization cues in mammals. While its sound localization has been tested extensively under free-field stimulation, many neurophysiological studies use headphones to present signals with binaural localization cues. The gerbil's behavioral sensitivity to binaural cues, howev...

Passive sound-localization acuity and its relationship to vision were determined for the echolocating Jamaican fruit bat (Artibeus jamaicensis). A conditioned avoidance procedure was used in which the animals drank fruit juice from a spout in the presence of sounds from their right, but suppressed their behavior, breaking contact with the spout, whenever a sound came from their left, thereby av...