Proper understanding of the time domain finds that equalization introduces time smear .
Time vs. Phase
Another noteworthy aspect of phase, timing and polarity is you cannot compensate a time delay with any amount of phase shift.
Time delay represents an infinite number of phase shifts at an infinite range of frequencies. Similarly, a waveform cannot be truly
out of phase unless it’s a single frequency (think sine or cosine wave). Therefore, the terms “reverse polarity” and “180 degrees
out of phase” are not interchangeable when discussing music waveforms.
Music Reproduction: It’s all in the Timing
The stereo effect is a fragile illusion based on the interference of the acoustic arrivals at the left and right ear. Timing and
amplitude differences over the audible frequency bandwidth for the arrival to each ear is the basis of the head related
transfer function (HRTF).
The brain has an uncanny ability to process and triangulate acoustic source locations from these combined arrivals.
However, this is not the only way that we localize sounds. In fact, completely covering one ear does not prevent you
from localizing sound. Give it a shot.
However, the perception of sound from only one ear will radically reduce one’s ability to the map out the acoustic
environment and will make speech seemingly less articulate in even a moderately reverberant environment. It is key to
have sound arrive to both ears for the brain to selectively focus on a source and while working to subjectively reduce the
masking background noise.
There are some often misunderstood aspects of phase, polarity and time. We know we can hear the acoustic cancellations and
summations that occur when soundwaves interfere in space on the path to our ears. This interference introduces frequency
response changes. However, put on a set of headphones and flip polarity on one channel and you might be in for a surprise.
You might logically expect the bass to become thin or weak. But the brain does not process this phase difference in the way that
you might think when the waveforms have not interfered acoustically. No audible comb filtering is introduced.
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