AA Locking Sounds Changed?

[serfma]

I used to fly trans a lot and I tried it again today for the first time in months and I realized the AA sound is a single toned sound. Does that mean there is someone locking on me and possibly a missile flying at my precious helicopter? I recall it used to be lower pitched for someone locking onto you and a higher pitched tone when there's a missile flying at you, so I'm making sure I'm not going crazy. So I'm not sure; AA lock sounds changed in one of the past patches?