As a member of a committee of the State of South Australia to discover cases of hearing loss in children up to age 16 in the State, I visited the audiology clinic of Professor Henk C. Huizing in The Netherlands. His method of testing babies and young infants was so impressive and simple that a similar apparatus was constructed for the Deafness Guidance Clinic in Adelaide by the sound engineers of Philips Electrical Industries. It is called an AudioFrequency Wobbulator.
This instrument differs from a pure-tone audiometer in that the sound emitted has not a set frequency but, by frequency modulation, "warbles" to and fro above and below the chosen frequency. In addition the rate of modulation can be varied. By combining these two methods of varying the sound a very great variety of "warbles" can be produced. The range of the instrument coincides with that of the conventional pure-tone