Yes, you need to send the "mute" information
for each part of your song. Storm uses the last
information (like channel 1 open, 2 = mute )
until some new information comes towards it.
When you heared all the song and return to start,
last information was "open all channels" and it stays
like that till "close channel 4" or similar.
So do like "EM-T Patrn" said, mark all parts that should
be quiet and use static mode to select an empty pattern.
Best regards,
Sven Basskilla