The Football Park Siren

Just finished watching another great video from the SAFootbaall Archive, the 1974 State match. I noticed that a more conventional lower pitch siren was used. But I know the next season had the car siren. This was used up until 1991, when the current siren replaced it. An extra tone was added to it in 2003, I think I recall some problems with the volume, so another tone was added to it to be heard better.
The car siren has to be the most distinct siren used at a major football venue. I wouldn't mind knowing who came up with the siren; why the 1974 one wasn't kept; and was it an AFL directive to replace it. Seeing as it lasted one season into the Crows foray into the AFL.
The car siren has to be the most distinct siren used at a major football venue. I wouldn't mind knowing who came up with the siren; why the 1974 one wasn't kept; and was it an AFL directive to replace it. Seeing as it lasted one season into the Crows foray into the AFL.