Computer Noise

<?php
    /* A.B. Carroll ben@hl9.net */
    /* I don't know what I'm doing, but try this. */

    function beep($frequency, $duration) {
        shell_exec("beep -f $frequency -l $duration");
    }
    beep(440, 100);
    for($x = 1; $x <= 50; $x++) {
        if( ($x % 3) == 0) {
            continue;
        }
        $y = $x % 4;
        $y = $y * 440;
        echo " > $y\n";
        $z = floor($x / 16);
        $y = $y + ($z * 220);
        beep($y, 100);
     }