<Li> Massive experiments demonstrate that ITD relates to the signal frequency f . Suppose the angular position of the acoustic source is θ, the head radius is r and the acoustic velocity is c, the function of ITD is given by: I T D = (300 × r × sin ⁡ θ / c, if f ≤ 4000Hz 200 × r × sin ⁡ θ / c, if f> 4000Hz (\ displaystyle ITD = (\ begin (cases) 300 \ times (\ text (r)) \ times \ sin \ theta / (\ text (c)), & (\ text (if)) f \ leq (\ text (4000Hz)) \ \ 200 \ times (\ text (r)) \ times \ sin \ theta / (\ text (c)), & (\ text (if)) f> (\ text (4000Hz)) \ end (cases))). In above closed form, we assumed that the 0 degree is in the right ahead of the head and counter-clockwise is positive . </Li> <Li> Interaural Intensity Difference (IID) or Interaural Level Difference (ILD) Sound from the right side has a higher level at the right ear than at the left ear, because the head shadows the left ear . These level differences are highly frequency dependent and they increase with increasing frequency . Massive theoretical researches demonstrate that IID relates to the signal frequency f and the angular position of the acoustic source θ . The function of IID is given by: I I D = 1.0 + (f / 1000) 0.8 × sin ⁡ θ (\ displaystyle IID = 1.0 + (f / 1000) ^ (0.8) \ times \ sin \ theta) </Li> <Li> For frequencies below 1000 Hz, mainly ITDs are evaluated (phase delays), for frequencies above 1500 Hz mainly IIDs are evaluated . Between 1000 Hz and 1500 Hz there is a transition zone, where both mechanisms play a role . </Li> <Li> Localization accuracy is 1 degree for sources in front of the listener and 15 degrees for sources to the sides . Humans can discern interaural time differences of 10 microseconds or less . </Li>

In order to localize the source of low frequency sounds the human auditory system uses