AirPods out of paired iPhone range chime?

[CrankinJland]

I'm using AirPods Pro 3 hearing assist mode.
They work great!
Yesterday I was wearing them when I left my apartment to dispose of the garbage. I didn't take the charging case nor the iPhone that the pods are paired to with me. I was about ten yards from home and heard a chime play just once on the AirPods.
On my return upon entering the apartment the same chime played on the AirPods.
I'm wondering if the chime is a normal function or have I messed with the setup (all the menus and different icons for the same functions was a bit confusing)

 

[CrankinJland]

After repeated testing, I have come to the conclusion that the chime is a normal feature whereby when the AirPods lose their Bluetooth connection by being too distant from the paired device they try to reconnect and emit the chime, when they are close enough to reconnect they do so and again emit the chime. I guess it's an undocumented feature.