To change the volume of a sound we need to use the snack::filter command. The snack::filter command is similar to the snack::sound command. The snack::sound command creates a new command to play sounds. The snack::filter command creates a new argument you can use with the command that snack::sound created. The snack::filter command has a lot of arguments. One that's useful for making games is the map argument. The map argument creates a filter that changes the volume of a sound being played. A filter that will make a sound quieter looks like this:

set quiet [snack::filter map .3]

Once you've created a filter argument, you can use it to play background music like this:

# Create a new sound command named music snack::sound music # Read the background music into the music command music read background.mp3 -fileformat mp3 # Create a filter - save the new filter argument # in a variable named quiet set quiet [snack::filter map .3] # Play the music, using the quiet argument music play -filter $quiet

The snack package can do many things with sounds. Here's a link to the full documentation for the package.