Haas effect

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The brain uses not just volume differences but also the time difference between the ears to calculate the position of the object emitting sound. Thus, normal panning is not an entirely natural way for the brain to pinpoint the location of a sound source. The interesting thing is that even though you use speakers, imposing a delay in one side still creates an impression of position. This is know as "The Haas effect ".

When two identical sounds come from two sources at different distances from the listener, the sound created at the closest location arrives first. To the listener, this creates the impression that the sound comes from that location alone due to a phenomenon that might be described as "involuntary sensory inhibition" in that one's perception of later arrivals is suppressed.

Now, because the speed of sound is appx. 343 meters/sec (or 34.3 cm/ms) at normal listening conditions, the distance between the ears, approximately 12 cm, takes 0.35 ms to travel, when the sound is coming straight from the side. So if the audio is hitting us in a 45 degree angle, pythagoras dictates that the delay is only 0.35 ms * sqr(1/2) = 0.25 ms. Sound coming from the front hits both ears simultaneously. This contradicts wikipedia which states the values to be 30-40 ms. Someone should test this.

The Haas effect improves stereo perception greatly on both headphones and even speakers despite obvious problems here. The only real downside is that mono compatibility is lost. Comb filter phasing occurs if you merge left and right into mono.

Availability in Buzz

The Haas effect is currently available in the following Buzz machines:

  • Joachim's DeepPan
  • Joachim's PowerPan
  • Joachim's ChannelStrip