As an old-time networker, this sounds like a classic usage for an SNMP Trap.

Your web page (perl code) will need to generate the trap (A simple UDP packet), and send it to a pre-configured Trap receiver (Possibly in a different state or planet).

The trap receiver (There are many standard ones, and is is simple to write a UDP receiver for this special case) will take action (such as playing an audio file) when a trap is received.

Typical usage for SNMP traps is network device related alarm conditions.

Perl modules beginning with "Net::SNMP" are your friends.