Works with most hot liquids with powders, I think I first noticed it in a mug of instant hot cider......

https://en.m.wikipedia.org/wiki/Hot_chocolate_effect

The hot chocolate effect, also known as the allassonic effect, is a phenomenon of wave mechanics first documented in 1982 by Frank Crawford, where the pitch heard from tapping a cup of hot liquid rises after the addition of a soluble powder. It was first observed in the making of hot chocolate or instant coffee, but also occurs in other situations such as adding salt to supersaturated hot water or cold beer. Recent research has found many more substances which create the effect, even in initially non-supersaturated liquids.
It can be observed by pouring hot milk into a mug, stirring in chocolate powder, and tapping the bottom of the mug with a spoon while the milk is still in motion. The pitch of the taps will increase progressively with no relation to the speed or force of tapping. Subsequent stirring of the same solution (without adding more chocolate powder) will gradually decrease the pitch again, followed by another increase. This process can be repeated a number of times, until equilibrium has been reached. Upon initial stirring, entrained gas bubbles reduce the speed of sound in the liquid, lowering the frequency. As the bubbles clear, sound travels faster in the liquid and the frequency increases

What he neglected to say, and would be important, is at 25% higher it is loud enough to cause permanent deafness, <50% higher, around 180, that's loud enough to kill a human. I wish he had asked the witness if he would sit for double the original volume, would that be disruptive? Now ask Trump.
16000 times louder....16000 times, when 2 times louder is well beyond the level that is deadly. Let that sink in. 8000 times louder than deadly. That's not only deafening for hundreds or thousands of miles in every direction (sound travels farther with less loss under water), it's undeniably deadly for miles....every time they ping it....to nearly everything. That level of sonic energy can shatter stone, what would one expect it to do to a tissue paper thin swim bladder?

I am astonished they're still trying this tech after the outrage at the hundreds or thousands of dolphins and whales it killed early on, years ago.

>> ^Tokoki:

Woah...mind blown (twice). I mean, I knew that light was slower in air, but ~1M m/s slower? Crazy...
And the "speed of push" being the speed of sound? Love these types of videos...


Ya, I have known forever that sound traveled in water faster than air...but I didn't think of the larger implications of what this meant in reality. And just like light, there is a formula for calculating the speed of sound in objects, which by conscience is also the speed of change in the object, something I never placed in the same realm before (sound was related to motion in my mind, but in reality sound IS MOTION).

It's scientific! But wrong. Sound travels faster in gasses with lower molecular weight, rather than lower density. Most people will tell you it's to do with density because of wrongness like this, but science is about facts, not popular opinion.

^Are you a sound engineer? If so, maybe you should read John Huntington's blog and learn a few things. Here's what he had to say:

"And so, when we have a sound system where we want people to hear some distance away from the stage, sound system engineers have to take this into account. Speakers at a distance from the stage (like at the concert pictured in the video) must be intentionally delayed to get them to line up in time with the sound emanating from the stage. This happens because the electrons in the cables transfer the audio signal out to the delay speaker positions effectively, for our purposes, "instantly", while the sound waves, vibrating air molecules, can take many seconds to travel. And if the "delay" speakers, remote from the stage, are not aligned in time (even milliseconds matter), the audience will hear either destructive interference called "comb filtering", or perceive an echo. (Interestingly, from what I saw on screen, it appears that the large video displays on the mall were actually delayed to match the slowness of the sound.)"

adn here are some of the comments on the thread. (some of these are really cool)

-"Very cool way to show this "lag".

To geek you out further. Since heat rises, many sports arenas can have a 10degree or greater temperature difference from floor to ceiling during a show. Sound traveling through the top of the room to the balcony's gets to the last row before the sound on the floor.

This is not a constant. During sound check the room is much more balanced. But put 5,000 excited dancing people in the room. Now try and calculate your delays."

and

-"I know the effect well. When I mixed sound for outdoor rock festivals and they'd often times have the mixing booth a 200 - 300' from the stage.
I'd always have to slip the headphones on and mix that way when timing was critical. It was the only way you could time changes properly.

Most sound engineers didn't know this trick and they would always screw up the timing and couldn't figure out why.
The same engineers used to criticize my use of the headphones as they said you have to mix for the audience not for the headphones.
Well you can't mix for the audience if you have a 1/4 second time delay."