Why do your ears have no problem distinguishing a sound located above your head from a sound located at your feet, even though horizontal timing cues are completely identical? The human brain decodes vertical elevation by tracking microscopic frequency notches carved by the pinna's upper folds. The Acoustic Physics of Vertical Elevation Perception In three-dimensional … [Read more...] about Interaural Spectral Pinna Cues: Vertical Elevation Perception
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Masking Threshold Dynamics: Critical Bands and Audio Compression
How can lossy audio codecs throw away 80% of an audio file's digital data without most listeners noticing any change in sound quality? The secret lies in psychoacoustic masking threshold dynamics and the 24 critical frequency bands of the human cochlea. The Physiology of Cochlear Critical Bands In human auditory physiology, the inner ear's basilar membrane acts as a … [Read more...] about Masking Threshold Dynamics: Critical Bands and Audio Compression
Binaural Beats Neurological Entrainment: Psychoacoustic Phase Tracking
Why does playing a 440 Hz tone in your left ear and a 450 Hz tone in your right ear create the perception of a pulsating 10 Hz rhythm inside your brain—even though that 10 Hz tone exists nowhere in physical acoustic reality? The phenomenon is binaural beating, born inside the brainstem's superior olivary complex. The Neurobiology of Binaural Beat Generation Unlike … [Read more...] about Binaural Beats Neurological Entrainment: Psychoacoustic Phase Tracking
Precedence Effect (Haas Effect): Echo Suppression in Headphones
Why does your brain completely ignore early room reflections arriving within 30 milliseconds, merging them into a wider, richer soundstage rather than hearing a distinct echo? The phenomenon is the Precedence Effect (Haas Effect)—the neurological master switch of spatial audio perception. The Neurological Physics of the Precedence Effect In natural acoustic spaces, sound … [Read more...] about Precedence Effect (Haas Effect): Echo Suppression in Headphones
Cone of Confusion Localization: High-Frequency Pinna Filtering
Why do sounds coming directly in front of you produce the exact same timing and volume differences as sounds directly behind you? The phenomenon is known as the Cone of Confusion—and only the intricate acoustic filtering of your outer ear pinna allows your brain to tell front from back. The Geometry of the Cone of Confusion In spatial psychoacoustics, human horizontal … [Read more...] about Cone of Confusion Localization: High-Frequency Pinna Filtering