Beards of similar length and greyness to mine might remember this was a project, probably from the brow of R. A Penfold posted in a monthly electronics magazine. Damnit, I can still recall a schematic: ORP12 and LED + lens broken beam detector, 555 timer as clock, 74590 binary counter, an EEPROM, 8 bit DAC and push-pull power amplifier based on TIP30/31 transistors. IIRC the crazy part was you needed to build an EEPROM programmer as step one, and hand program the sound sample using a BBC micro parallel port. Digitised dog barks were available by floppy disk in the mail.