The sound quality is much better after exporting, I assume this is likely due performance issues when creating sounds on real time using JS, so maybe one could use most of the same exporting logic to internally save a cached version of the sound (instead of always generating it on real time) to avoid such issues.

Very nice! Reminds me of loglo, a similar app posted a few weeks ago for spreadsheet geometry: https://news.ycombinator.com/item?id=23542876

Is there a button to play the sounds on the site?

Just click any cell

This was my issue as well.

I thought I was looking at something like Ableton Live's session view, where each cell could be a mathematical function or any instruction a spreadsheet offers.

I clicked only on the A1 "$t"-cell, so obviously I didn't hear anything.

Yep, and the cell furthest down in any column contains the loop that makes the sound repeat.

What about the whole composition? Or is that not what this is about?

Is there a light mode?