I was able to throw this together after taking a gander at the link provided by Anonymous Monk in this thread:

use strict;
use warnings;

use FileHandle;
use IPC::Open2;

my $pid = open2(*Reader, *Writer, "perl dialog.pl");

print Writer "42\n";
chomp( my $got = <Reader> );
print $got, $/;
[download]

Notice the explicit use of chomp() as well as terminating the sent string with a newline. I recommend you alter your dialog.pl script to chomp() user input:

chomp( my $age = <> );
[download]

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)