Remove the door panel.
Front
Sliding door
Remove the bolt (A). Then lift the speaker (B) straight up to release the lower clips (C).
If you pull the speaker out too far from the door, you will damage the lower clips.
Honda Odyssey Service Manual > HondaVAC™ System Description: Sound Pattern of the Buzzer Pattern 1 ONOFF120±12 ms880±88 ms1000±100 ms Pattern 2 OFFON3000±300 ms ...