I found the "Greater Simple Sound Effects" circuit hiding away in Elektor magazine from May 1980 (p21, by H. Thienel). It was just a short article describing a small variation on the original "Simple Sound Effects" circuit published in Elektor May 1979.

The original "Simple Sound Effects" circuit is a clever use of the (at the time) new CMOS technology - a CD4040 12-Stage Ripple Counter, and CD4049 inverter.

More details of my investigation of the circuit and how it works can be found on the web page for the project repo here.