Spooky Sounds Solution

How It Works

Gather the data.
Notice that there is exactly one timestamp during which every speaker plays something (This is time 0), and further note that the sounds coming from each speaker are unique and encompass all sounds that are ever played which is immediately following beeps that sound like a race start (it should be quite clear). This both gives you a sync/starting point (that is time slice 0, and the next set of sounds are the first real data), and gives you a unique assignment of a sound to each speaker: 4. During each subsequent time slice, various speakers will be playing various sounds, or a short click indicating a "null". Each of these sounds indicates that you should draw a line between this speaker and the speaker assigned to that sound. Each time slice will spell out a letter.
Spelling out all letters in order yields the phrase "FOLLOW THE BLACK CAT".
Follow the cat sound around the speakers, ignoring the index time slice (if you don't, you get an extra unnecessary line, which thankfully doesn't interfere with the solve) and any time slices where the cat isn't played (these exist largely to dissuade teams from doing this until they have the explicit instruction to do so.
Look at what you've drawn.

Example Time Slice

For example, in time slice one, the following sounds can be heard on the following speakers.

Connecting the speakers that the sounds are playing from with the speakers that are assigned those sounds yields the following.

This should hopefully be easily recognizable as the letter "F".

Solution

PENTAGRAM

Design Notes

Construction Notes

This puzzle was originally designed to be done using separate speakers with individual media players attached, started at synchronized times. It turns out that different media devices, no matter how similar, end up drfiting by little amounts, enough to throw off the puzzle substantially over the course of minutes and hours.