Bluetooth notification beeps too loud

2012 Mazda3 sport skyactiv
I have a 2012 Mazda3, with an Iphone 6 connected to Bluetooth. The system produces a deafening double beep when a call comes in, or a call ends, or after Google maps gives a message. The volume of the notification beeps is constant, regardless of the volume setting on the car radio or the iphone.

Is there a way to modify or eliminate the notification beeps?