Reverberation and pitch

[duncan]

This might seem a bit off the wall -- ahem, so to speak -- but it's been bugging me for a while.

I'm listening to acoustic music recorded in a concert hall, typically classical. The last chord is played, the musicians stop, and it's time for that glorious moment when the reverberations slowly die out around the hall. But the pitch isn't quite steady: it rises subtly and gradually, maybe a quarter tone, before it's gone.

Although I don't always hear this, it happens often enough to make me wonder if my experience is unique, and if there's anything behind it. It can't be a true Doppler effect, because I'm sitting still, and it's not like the walls of the auditorium are rigged to move inwards on hydraulics like the garbage mashers on the detention level of the Death Star. So what the heck is this? It seems like the broad possibilities are,

1. An acoustic phenomenon that there's some obscure explanation for
2. Something psychoacoustic that is recognized but might have no good explanation yet
   
3. Evidence of something uniquely wrong with duncan's head.

 

[Artie]

I'm not sure if I'm off track with what you're saying, but I've noticed, (for several decades), that the pitch of a song seems to rise right at the end of a record. Just as it's fading out. It's a weird phenomenon.

 

[duncan]

That sounds right to me. If we're talking about the same thing, it must be something more directly related with volume level, and not reverberation per se.

 

[toddalin]

This might seem a bit off the wall -- ahem, so to speak -- but it's been bugging me for a while.

I'm listening to acoustic music recorded in a concert hall, typically classical. The last chord is played, the musicians stop, and it's time for that glorious moment when the reverberations slowly die out around the hall. But the pitch isn't quite steady: it rises subtly and gradually, maybe a quarter tone, before it's gone.

Although I don't always hear this, it happens often enough to make me wonder if my experience is unique, and if there's anything behind it. It can't be a true Doppler effect, because I'm sitting still, and it's not like the walls of the auditorium are rigged to move inwards on hydraulics like the garbage mashers on the detention level of the Death Star. So what the heck is this? It seems like the broad possibilities are,

1. An acoustic phenomenon that there's some obscure explanation for
2. Something psychoacoustic that is recognized but might have no good explanation yet
   
3. Evidence of something uniquely wrong with duncan's head.

Can you provide a YouTube example?

 

[Lavane]

Maybe the walls, etc. in the environment absorb the lower frequencies quicker?
That's all I got.

 

[twiiii]

I know one thing pitch seems to change as you increase and decrease the volume. I heard it first when my dad would play music on his mothers grand piano. . I know musicians can change pitch on purpose with the breath support pressure and throat changes playing wind instruments. I have also heard speakers change pitch with different volume levels thanks to friends of mine and my DAD who all had perfect pitch who pointed out the issue. He said some times he had to change his finger on his violin at different volumes but that he thought that was do to the pressure and speed of the bow across the string. What blew me away was you could hear the pitch changes my Altec speakers made at different levels that my Bozaks didn't do to the same degree. All this is just observations on my part I don't know why. Even a tuning forks struck next to the ear seem to change pitch as it is pulled away from the ear and the pitch becomes less intense.

 

[automojo]

I know one thing pitch seems to change as you increase and decrease the volume. I heard it first when my dad would play music on his mothers grand piano. . I know musicians can change pitch on purpose with the breath support pressure and throat changes playing wind instruments. I have also heard speakers change pitch with different volume levels thanks to friends of mine and my DAD who all had perfect pitch who pointed out the issue. He said some times he had to change his finger on his violin at different volumes but that he thought that was do to the pressure and speed of the bow across the string. What blew me away was you could hear the pitch changes my Altec speakers made at different levels that my Bozaks didn't do to the same degree. All this is just observations on my part I don't know why. Even a tuning forks struck next to the ear seem to change pitch as it is pulled away from the ear and the pitch becomes less intense.

That's interesting-I have also heard the same thing with speakers.
I have spent the last couple of years working on being a better listener, and really hear all the cool things that are in a live performance or recording.
It's really been a amazing journey so far.
I have always liked pretty much a genre's-but find my self really enjoying those I didn't prefer so much more.
Lot's of things I missed!

 

[duncan]

Wooo... I'm glad to have it confirmed it's not just me being strange. Thanks all.

Once thinking about it in terms of volume difference instead of echoes, I was able to find this summary on stackexchange -- the gist of which is, perceived pitch varies almost exactly with frequency but slightly with volume too, that variance being at most about 1%. So it's definitely a known psychoacoustic thing.

 

[toddalin]

Simple enough to test, though the OP has provided no examples for us to listen too thereby making it difficult for us to hear what he is hearing.

Just take an RTA or o-scope and watch the display as you turn up the volume and see it the frequency shifts.