Galaxy S4 w/ Sena SHM10 BT headset - music vs. nav instructions

What I am trying to do  is use my S4 as an all-in-one music/nav/phone solution via BT when I ride my motorcycle (and later when I get a A2DP equipped car).

Currently, I am using a Garmin motorcycle GPS and my S4 for music/phone and paired with my Sena SHM10 BT headset.  Everything works well.  Music plays via phone to BT, phone calls (directly from S4) and Nav instructions (direct from Garmin) perfectly interface.  Music stops promptly, call or directions come through and music picks right back up.

I am using your newest Beta version (.02).  Music is playing through Share Music 2.1.0.  For Nav, I have tried Sygic, CoPilot, & Google Maps.  I am running Android 4.3 on the S4.

When trying to use S4 to do Nav (and music/phone), I run into the following problem.  Music plays, music stops when the Nav app signals a voice direction (audible "thud or bump" when music stops), there is a ~3.5 sec pause, another audible "thud or bump" as the Nav voice kicks in, and only the last word or two of the Nav directions are heard, then it quickly switches back to music audio.  

I have tried the directions in other posts (setting TTS delay (have tried up to 6 sec), upgrading to the new Beta, BT mono, BT A2DP, etc) and none seem to work.  The sequence above is always the same.

This issue is also present when the BT connects to car audio in Acuras and Toyotas (rentals that were BT equipped), not just the Sena SMH10.

If I am not playing music, Nav voice over BT works flawlessly.  Immediately kicks in, gives directions and kicks off.  

It seems to be some embedded in how the S4 internally switches between BT outputs.  Music vs. phone switches work perfectly.  Throw a Nav app into the mix and the S4 BT has problems.

If one uses the the phone's speakers, then everything works smoothly.

Any thoughts would be most welcome.

Thanks.

As a follow-up, I have played more with the S4 today. Basically, if I force Media Audio into Bluetooth Mono, then the Nav apps will integrate smoothly with the audio output. It will seamlessly switch between music and Nav directions and will do so immediately. Any adjustment to TTS delay has no effect in either mono or A2DP. The nav voice engages immediately regardless of TTS delay. Any other combination of mono/A2DP/Let-App-Decide results in the delay issues noted in my last post. Unfortunately BT mono destroys the music quality.

Any thoughts on how to get A2DP (music) and Nav voice (mono) to work together would be great.

Thanks.

There were some changes in Android 4.3 that affected regular non-phone call audio to Bluetooth mono. When trying to send audio to Bluetooth mono, the older Android 4.2.2 and earlier would simulate a phone call. That was changed in 4.3, so that it send raw Bluetooth audio without simulating a phone call.

Try the latest Beta and see if the Text-To-Speech option works better.
They are a work in progress, Beta version downloads are located here:
https://soundabout.forumotion.com/f8-download-beta-versions