At the top-left are the meters:
There are as many meters as the PSG used by the song has channels (3 for most 8-bits, or more if using specific hardware such as PlayCity, Darky, SpecNext, etc.).
The meters show the waveform of each channel.
The only interactions are:
- Left-click to mute/unmute a channel.
- Right-click to solo/unsolo a channel.