France is using only two tone sounds but have five different sounds.
One for the Police, one for the Gendarmerie, one for the Fire Service, one for the UMH/SAMU ( mobile hospitals/emergency ambulances) and one for the private ambulances/medical transports).
It is the latter one that use two tones in sequence of three with a gap between these groups of sounds.
420hz + 516hz + 420hz + 1,5 second gap.
I can agree of that this siren sounds stupid but these ambulances are not emergency ambulances and have not the same priority in traffic.
Probably because of the lower priority the siren sound different than high priority vehicles.
Michael