We feel there has been an increased use of American style “wailing” sirens on our emergency service vehicles. We think this is a mistake, and that these are less safe. We believe they also represent a loss of a small but important bit of cultural capital.
A wailing siren's constantly changing pitch can disguise Doppler effects and interaural timing cues, which can make it difficult to discern the direction and distance.
We think a two-tone siren provides more predictable and consistent auditory cues that the brain can use for localisation.
Also, we want our emergency personnel to behave - and be treated like - British bobbies, not American cops. We view the siren an important subconscious nudge as to who we are and how we should behave.