Defect Detector doppler

[AV3]

So I've noticed that in my copy of TRS22PE, the JR defect detector seems to like to give a doppler effect on the sounds when a train has passed. Is that supposed to happen or is it something one of the service packs has caused? I don't remember if I had this happen in TRS19 but as far as I remember, it wouldn't do that with Trainz A New Era.