Numbered buttons correspond to keyboard shortcuts. Spacebar stops all currently playing sounds. The sound effects are place holders - if you remix the project it should be easy to swap them for whatever sound effects you'd prefer.
Base images: https://commons.wikimedia.org/wiki/File:Korg_Electribe_MX_(EMX-1).jpg By Ben and Kaz Askins. Used under Creative Commons Attribution-ShareAlike-3.0 https://www.flickr.com/photos/dominicotine/7862424222/ By Dominick. Used under Creative Commons Attribution-ShareAlike-2.0 Obviously the project itself is licensed under the usual CC license as required by Scratch for public projects: http://creativecommons.org/licenses/by-sa/2.0/deed.en