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Notes -
Medical/neuroscience question for those of you with domain expertise.
It's well-established that the "clock speed" of a person's brain runs very quickly in their youth and slows down as they get older. This is why children's perceived sense of time is so much longer than adults': I'm sure you remember sitting in the back of class in primary school willing the clock to tick just a little faster, but nowadays you sit down at your desk at 9 a.m. and before you know it it's already lunchtime. Many people independently report a sensation of perceived "slow motion" when they find themselves in intense life-or-death situations, which is likely due to the same effect: your body produces massive amounts of adrenaline which temporarily jacks up your brain's clock speed.
Years ago I noticed a potentially related phenomenon. Back when I was a much more avid listener than I used to be, I would often listen to music first thing after waking up, before I'd even finished drinking a cup of tea. I noticed that songs I listened to at this time of day would sound like they were being played at a higher tempo, compared to listening to the same song later on when I'd woken up fully. My theory is that, as my brain hasn't fully woken up yet, its clock speed is marginally reduced (compare an old computer which runs a little slowly for a few minutes after a reboot), causing my perceived sense of time to temporarily speed up until I've fully woken up. The effect is subtle enough that I wouldn't really notice it unless being exposed to a stimulus whose perceived duration I'm already familiar with (i.e. a song I've already heard). And sometimes I get the opposite effect, where a song I've heard before sounds slower than I expect it to. Maybe this is a product of my brain's clock speed having increased, if I'm exerting myself physically?
Is this theory in any way neurologically plausible?
I've noticed a different one recently. The Doppler effect is caused when a moving object emits waves, and the position of the object (and hence the changing position of the source of those waves over time) causes the wave's perceived frequency to change over time. The pitch of a motorcycle engine appears to rise as it drives towards you, then falls as it drives away from you; the light of stars moving away from the earth exhibit a redshift.
On Saturday morning I woke up at 8 a.m. to run a half-marathon. I was tired and hungover, and listening to a favourite album I'd listened to several dozens of times before. In addition to changes in perceived tempo I described above, I noticed certain points in the album where the music actually sounded out of tune. (For reference, I have perfect pitch and can reliably identify the pitch of an individual note, play a song by ear or identify the key of a piece of music.) This definitely wasn't an error on the part of the artist, nor an encoding artefact (it's the same set of FLAC files I've been listening to this album on for nearly a decade, and I've never noticed anything sounding out of tune before). Any disruptions to perceived tonality had dissipated by the time I got to the halfway mark and began my return journey. This suggests it's a psychoacoustic effect caused by fatigue or being hungover.
The "changes to perceived tempo" thing is straightforward: reduced neural clock speed -> time seems to pass faster (and vice versa). But this change in perceived tonality is much odder. Why would a reduced clock speed affect the perceived pitch of a note, in addition to its duration? A computer that's running slowly takes longer to carry out computations (up to and including the display's frame and refresh rate), but it doesn't systematically make every pixel a few shades darker. And it isn't even happening globally: it's not as though the song was recorded in E major, but subjectively sounds as if it was recorded in E-flat until I've woken up fully. It sounds out of tune, meaning my brain is misinterpreting the pitches of certain notes but not others.
Any ideas?
The Doppler effect occurs due to wave peaks/troughs arriving at your sensor faster or slower. It’s only going to be affected by starting frequency and relative motion.
I think it’s more likely that you have some other sensory interference, like rushing blood or ringing, which changes during the day. For all I know the water content of your skull changes its frequency response. If your sinuses are stuffed you’re gonna get some weirdness.
I know the phenomenon I'm describing isn't actually caused by the Doppler effect, I was just using that as an example of changes to perceived pitch.
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