$expr .= "(\$f0 >= $freq[$i] && \$f0 <= $freq[$i+1]) ||";
my $r = Spot::ftor($freq[$i], $freq[$i+1]);
# $hint .= "m{$r\\.} ||" if $r;
$expr .= "(\$f0 >= $freq[$i] && \$f0 <= $freq[$i+1]) ||";
my $r = Spot::ftor($freq[$i], $freq[$i+1]);
# $hint .= "m{$r\\.} ||" if $r;