The Phase Matters

http://www.maximalsound.com
It seems usually admitted that the human hearing isn't sensible to the phase relation between frequencies. But since this phase relation also modifies the waveform, an attentive listening may detect variations. I've added allpass filters to create a phase shift at 400 Hz per 90° increments.
You can hear how reverberations and transients are affected by the phase shifting. The first 90° is obvious on the reverb, the stereo placement of the guitare and percussions. The following loops are differently affected by the phase variations. The guitar tone amost doesn't change while the percussions may vary.

Note also that a limiter inserted after an allpass filter or more will have a different behaviour because of the peak value modifications. In this demo the maximal peak values may change from -2.32 dB to +3.81 dB. Which is not a detail for human hearing nor for any downstream processor.

Category:

Education

Tags:

• audio
• mastering
• phase
• shifting
• maximalsound
• allpass
• filter
• maximal sound
• www.maximalsound.com

[LaurentMxSnd]

Sinus waves are meaningless since the have no harmonics. They're pure tones. So, no phase shift can be observed among the different frequencies. Music and sounds always contains different frequencies, so any phase shift affects the waveform.

Using a square wave produces the most obvious results on the waveform which was desirable for this demonstration.

[14wasp]

Click 0:07 and listen for a few seconds

Click 0:21 and listen for a few seconds

To me it sounds different

[Parkinson9999]

To see how a square wave appers after it's played back through a SUPPREME (and of course expensive) headphones, visit innerfidelity com website, they have conducted such tests. Though it looks like anything but a square, it still sounds like a square.

[socketryanist]

Of course it changes the waveform. However that has nothing to do with whether it is AUDIBLY DIFFERENT or not (it's not, phase changes are only audible WHILE they're changing because a sliding phase shift is the same as a slight pitchbend)

[metabog]

Very nice demo.

[Iwasaproblemchild]

Now do it on a sine wave...

[TigerLST]

I have always felt that phase coherence and impulse/transient behavior in audio gear and loudspeakers to be very important. A system capable of a clean phase/transient/impulse response just sounds right to me. Speaker systems that have higher order electrical filters typically sound unnatural to my ears. Most argue that the difference is inaudible but I can hear it under most circumstances. Someone should make a blind test! Thanks for posting this.

[triggr357]

can someone tab this out? its beautiful.