The Case Of The Missing Audio in CV3

Both of Medusa's attacks and the teeter-totter obstacle have missing audio data. You can verify this by setting a breakpoint on $E249(j)/$E25F(u) when encountering either of those.  The audio track data for each of them is partially set. The teeter-totter was intended to use a single square channel, while Medusa's attacks seemingly were intended to use a square channel and the noise channel. I say "seemingly" because the setup for Medusa's attacks is the same as the silencer for the water droplets.

So were the water droplets using removed audio? It's difficult to say. The silencer seems to do exactly what it's supposed to. In CV3u they remapped Medusa's attacks to the silencer, so it would seem that was intentional. Except... The water droplet sound effect uses two square channels, not the noise channel. So why would the silencer halt the noise channel? 

There is some unused audio data (at least in CV3j) with an odd feature. The first byte was #ff (undefined). Ignoring that it was undefined, the obvious thing was that there was an unused audio data pair. I remapped Medusa's attacks to it and tested the results.

It sounded like the throwing axe sound. I copied the audio data and tried searching the ROM for other occurrences of it. Sure enough, it was the throwing axe sound. I was equally disappointed and thrilled. If I am correct, Medusa's arrow simply used the same sound effect as the throwing axe. It fit pretty well.

I tried remapping the teeter-totter to it, but the resulting square channel audio was clearly unintended. 

If I remapped the water droplet silencer to the unused audio data, it seemed to work well initially. The whishy-whooshy sound played when the block dissolved. However, within seconds audio artifacts started appearing. This could have just been a bug in my emulator, but it was reminiscent of a an audio bug I used to hear in Top Players Tennis on my NES hardware. So my money's on Medusa's arrow was supposed to use a modified throwing axe sound.

Unfortunately, there was no other unused audio data to work with.