https://support.garmin.com/de-CHAudio output for zumo devices on the motorbike
The following items can be used to obtain audio output on a zumo device on a motorbike:
A Bluetooth headset
Only usable if your device is Bluetooth enabled.
A wired headset
You can run an audio cable from the cradle or audio output directly to a helmet or headset.
A 3.5mm audio cable
You can connect an audio cable from the Zumo audio output to the motorbike's speakers.
The connectors on the side of the Zumo motorbike mount are a standard 3.5mm audio out connector and a 2.5mm microphone connector.