Good! I added Audio::DSP, and it works, provided that you give it a specfic file to read.

#!/usr/bin/perl

use strict;
use warnings;
use Gtk2 '-init';
use IO::File;
use Audio::DSP;

$|=1;

my $mw = Gtk2::Window->new('toplevel');

my $t = Gtk2::Table->new(1, 2, 0);
$mw->add($t);

my $label = Gtk2::Label->new('Example');
$t->attach_defaults($label, 0, 1, 0, 1);
$label->show;

my $button = Gtk2::Button->new('foo');
$t->attach_defaults($button, 0, 1, 1, 2);
$button->signal_connect( 'clicked' => sub { exit } );
$button->show;

$mw->show_all;

my $dsp = new IO::File("</dev/dsp");
my $event_source_tag = Glib::IO->add_watch(
  fileno($dsp),
  'in',
  sub {
    my ($buf, $chan, $fmt, $rate)  = (4096, 1, 8, 8192);
    $dsp = new Audio::DSP(buffer   => $buf,
                          channels => $chan,
                          format   => $fmt,
                          rate     => $rate);
    my $seconds = 5;
    my $length  = ($chan * $fmt * $rate * $seconds) / 8;
    
    $dsp->init() || die $dsp->errstr();
    for (my $i = 0; $i < $length; $i += $buf) {
        #records
        $dsp->read() || die $dsp->errstr();
    for (;;) {
        #playback
        $dsp->write() || last;
        }
    $dsp->close();
    }
});

Gtk2->main;
0;
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