Binaural effect, (from the Latin bini — pair, two, and auris — ear), a psychophysiological phenomenon consisting in the fused perception of the sounds received by the right and the left ear. Under natural conditions the signals differ in the time of arrival of the sound (the difference in arrival times Δt), in intensity (the difference in intensities ΔI) and in its spectral “colouring”. The sound reaches the ear turned towards the source earlier and with greater intensity. The difference in spectral “colouring” is caused by the fact that the diffraction of sound at the head and the pinnae depends on the angle at which the sound arrives. The binaural effect underlies the ability of humans and animals to determine the direction of a source of sound, and also the stereophonic effect. At frequencies below 1.5 kHz this ability depends mainly on Δt, and at frequencies above 3 kHz — on ΔI. Errors in determining direction in the horizontal plane are about 3°. When there are several sources separated in space, the binaural effect makes it possible to perceive them independently, and so increases the resistance of auditory perception to interference.