It is not muted. Waze announcements pause Slacker and are played through car audio.
Because of the way BT works, perhaps it's better to turn off BT at the phone to achieve what you want.
I think that's because Waze may be set to send those announcements to the Bluetooth hands-free profile, rather than the Bluetooth audio profile (A2DP).
The iPhone, and Androids for the most part, direct their audio output to a device the presents the A2DP profile. The Model S presents the A2DP and headset profile. Model S tells the phone "Oh, hi, I'm an audio destination AND headset destination." When paired, the phone directs its audio to the device with the active audio profile. Only certain apps - for example, Waze, Google Now, and (gasp) the phone app choose to use the hands-free destination - this is sometimes user-selectable, sometimes not.
Reference:
http://en.wikipedia.org/wiki/List_of_Bluetooth_profiles#List_of_profiles
I think what HankLloydRight is asking for is a mixer of audio from the Model S' other media sources (radio, USB, or internet) with the Bluetooth A2DP paired device, so that the alert sounds, etc that are only sent by the phone to A2DP profile when connected can still be heard.
Example:
Model S turns on, pairs with iPhone. Model S tells iPhone it has Hands-Free and A2DP profiles available. iPhone connects to both, but routes its outgoing audio to the A2DP destination, since it's there.
Driver listens to favorite radio station or Slacker radio. A text comes in, and the alert is sent to the Model S A2DP profile - but not played on the speakers.
Model S tells the iPhone that the A2DP profile is still active, but it doesn't mix or interrupt the Slacker radio stream.
Driver never hears the text message alert tone.
In bollar's example, Waze "Uses Bluetooth if available" in its settings.... that means Waze tells the phone to pick up the HANDS FREE profile to send the audio alerts. Model S will then pause the current audio stream - even the A2DP from the phone, if playing! - and play the Waze alert.
bollar, try telling Waze to NOT use Bluetooth, then select your phone as the audio source, and get the Waze navigation. THEN select another source while you're driving, and see if you hear the alerts. Then you'll see what HankLloydRight (and I) are experiencing.
To fix this: Tesla firmware either needs to
- disable it's A2DP profile when that source is not selected.... but this is not preferable, since you won't be able to select the device if it's not connected using the A2DP profile, and not preferable since you won't hear your phone when listening to the other source at hgh volume
- MIX the A2DP input with the current audio source (radio or, Slackr, USB)