The parentheses grab into $1, but grep works with $_.

Also, there is a problem with your regular expression. It will match any file containing .ram, not just files ending in this extension.

Be aware that as you are matching case insensitively, your regexp will also match files containing the string .RAM or .rAm. I'm assuming this is okay. Try:

my @audiofiles = grep { s/\.ram$//i } readdir DH;
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