Syph79 wrote:

Jeez, Reg, that’s not a fun situation. Is there any explanation as to why the op was only a temporary fix, and why it wouldn’t work if you went through it (or something else) again?

acemuzzy wrote:

Yeah I was trying to figure that out too. Can reach ear with the direction out? I thought it was mainly the relative time of the she sound arriving at each ear? In which case hard to fake from speakers, easier from headphones??

Similar to stereoscopy, stereophony is based on combining information in the brain from the two ears, creating a robust illusion that confers the stimulus a special character of perspective known as three-dimensional (3D) depth and localisation. Both in the visual and auditory modalities, this character contributes to creating ‘objects', which are easier to segregate and identify than what would have happened if a single receiver had been available. For example, sound coming from a source on the right side of a subject reaches the left ear later than the right ear, as it has to travel further, and it reaches it with a lower intensity, as it has experienced the head shadow effect. The further to the right the source is located, the larger the interaural differences. If the two ears process sound in such a way that interaural differences are accurately encoded in the volleys of auditory-nerve action potentials in response to the sound, two complementary tasks are left to the brain: to detect that particular patterns of action potentials from the right and left side correlate so well that they can be ascribed to a single, definite object, and from the asymmetries between the two correlated inputs, to localise this object in some horizontal direction. These tasks are strongly frequency dependent, because the head shadow effect hardly affects low frequencies that experience diffraction by the head; conversely, timing differences are less efficiently encoded at high frequencies because the auditory neurons cannot encode the fine structure of high-frequency stimuli, but only their envelopes. The duplex theory of Lord Rayleigh [1907] was brought forth to account for the need for the brain to switch from timing to intensity cues, i.e. from interaural time differences (ITD) to interaural level differences (ILD) to locate sound sources with increasing frequencies.

Thus, when submitted to this analysis, competing activities will be identified as separate objects located in different directions to which it will be much easier to pay (or not pay) attention than it would have been with a monaural input providing a flat, 2D sound landscape.