Perception of time shifting

(This page comes as an appendix of the page Audio temporal alignment)

We provide here a simple example of slight temporal shifts between and original signal and an altered signal, in order to illustrate our assertions on the perception of such phenomena.

Please note that all the sound examples in this page should be played with headphones.

The original item, the altered occurrence, and the stereo mix with perfect synchronization are provided below.

Original Altered Stereo mix (no shift)
[dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_item.mp3] [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_oc.mp3] [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_0.mp3]

The following table shows the perceptual effect of slight time shifts (between 0.01 and 0.08 s), either positive (the occurrence, on the right, comes a little after the item, on the left) or negative (the occurrence is a little ahead of the item). One notes that below 0.03 s, a unique sound is heard, that is perceived as moving in the head. Over this approximate threshold, the sound progressively splits into two separated sounds.

Shift Negative Positive
0.01 s [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_-1.mp3] [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_1.mp3]
0.02 s [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_-2.mp3] [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_2.mp3]
0.03 s [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_-3.mp3] [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_3.mp3]
0.04 s [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_-4.mp3] [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_4.mp3]
0.05 s [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_-5.mp3] [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_5.mp3]
0.06 s [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_-6.mp3] [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_6.mp3]
0.07 s [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_-7.mp3] [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_7.mp3]
0.08 s [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_-8.mp3] [dewplayer:http://www.mathieuramona.com/uploads/Main/audioalign/deltaT_8.mp3]