I found this video which at around the 5 minute mark the lead singer asks the crowd to jump. The crowd obliges and jumps. A few seconds the camera angle changes, and again the singer asks the crowd to jump. From this different angle I noticed a wave ripple through the crowd.

Well that's interesting, I thought. I wonder if this is wave is caused by the speed of sound. After all if you ask someone to jump from different distances they will jump at different times.

At 05:06,314 the wave has well begun at the front, the back still preparing for the J- in jump to hit them.

At 05:06,314 the wave has well begun at the front, the back still preparing for the J- in jump to hit them.

At 05:06,564 the first fists start to go up at the back of the crowd.

At 05:06,564 the first fists start to go up at the back of the crowd.

This gives us around 250 miliseconds for the wave to start at the podium, and end up at where the crowd is. Sound travels at room temperature at around 340.29 meters per second. This comes down to .34029 meters per milisecond, multiplied by 250 miliseconds is 85 odd meters. Now to determine where the crowd starts and where the camera is we need to find some archive footage that gives us an overview of what is happening.

Using aerial footage of Rock in Japan, where this footage comes from, we can accurately determine where the festivities took place.

https://s3-us-west-2.amazonaws.com/secure.notion-static.com/e5506588-5dc6-4067-966a-298625d2eada/Untitled.png

It's easy to spot where the stage would've been if we explore the world on Google Maps. In fact I found out this picture was taken from a ferris wheel

https://s3-us-west-2.amazonaws.com/secure.notion-static.com/fac318d8-f6b8-49b3-b478-0e3a85bf9534/Untitled.png

Enhance! Overlay! Do everything!

https://s3-us-west-2.amazonaws.com/secure.notion-static.com/10017582-6f28-4e30-836e-3b01aa1dcb0b/Untitled.png

Now regretably I cannot get an angle as acute as the one but with some cropping and skewing you can make a reasonable approximation. As you can see there are two white dots on the picture, which is where I approximated the stage and the camera viewpoint to be. After adjusting it a bit, taking into account zoom angles, looking from above it looks like this:

https://s3-us-west-2.amazonaws.com/secure.notion-static.com/0899a2f3-65b8-4e6a-b5d9-25ebbd38d43b/Untitled.png

246 feet is 75 meters. If the people did indeed form a wave simulating the speed of sound our target would've been at 85 meters. That said, 75 meters is pretty close especially give how little data I have to work with. An of course people don't just jump based on sound. They see the crowd in front of them jump and might jump before they've heard the beginning of the word jump.

So, does this prove my idea that you can meassure the speed of sound at a babymetal concert?

Maybe?