Do you mean when the sound is coming from the instrument cluster? There is a number of reasons why the car does that - the ACM or other modules are not booted/ready yet, the car has sat for a while, battery is low, and more.
The ACM and all other modules boot up every time you turn on the car... Regardless, there are a number of reasons the car changes the location where the sound comes from - many are known (such as the few I listed above), many scenarios can't be explained by users. The ACM could be busy reading other internal CAN-Bus network traffic when this happens as well. Either way, the car is designed to do this.