Bluetooth – Why Only Hear Sound from Speakers with A2DP Headset Connected

You could try using the hcidump utility from the package bluez-hcidump to monitor your bluetooth devices and gain in-depth information:

sudo apt-get install bluez-hcidump

In the package description, it is noted that:

The hcidump utility allows the monitoring of Bluetooth activity. It provides a disassembly of the Bluetooth traffic and can display packets from higher level protocols such as RFCOMM, SDP and BNEP.

You can use the utility to log the output from your device to screen or file; where hciX is your own bluetooth device (hci0 is the default and used if you don't specify anything with -i), you can run:

sudo hcidump -x -i hciX

You can save the dump to file by appending to the command -w ~/output, and if you specifically want to know about the audio data you can use the -A switch and thereby extract SCO audio data, although in this case you must always specify an output file:

sudo hcidump -x -A -i hciX -w ~/output

You can view a saved dump file by using

sudo hcidump -r ~/output

There are a lot more specific options that you might want to investigate; you can filter by packet type if you want, as by default all packets are dumped. Please see man hcidump or the Ubuntu manpages online for more information.

The only other option is to install wireshark and see if it can detect your devices; if it can, it will be able to analyse usb and bluetooth traffic, as noted here, but hcidump should give better results.

I too do have the same JBL flip as yours and I do face the same issue, sometimes we dont hear any sound after pairing.

I am not an expert but after hit and trial: I realized you need to click on the "bluetooth" icon on top right and choose "JBL FLIP" under scroll down and move tab to "Connection ON" and then test it by clicking on sound settings

** Short flow:

*blue-tooth icon>> JBL flip (after pairing)>> move tab to COnnection ON>> sound settings>> choose JBL flip>> Choose the mode HIGH Fidelity Playback (A2DP)>> "Test Sound"

You see a "Speaker Testing for headset" window. Test it by hitting on the left and right (Front left and Front Right). You can hear the sounds on the JBL speaker.*

Note: Sometimes when you play Videos through VLC player and if you pause it for a short-while to take a break like say ten minintes. When you come back and hit play: you might not hear the sound on the JBL nor the computer speakers (Sometimes). I just UN-pair and pair speakers: Do the same test. It works! :)

This is just a workaround.

Same problem when you connect a headphones- it doesn’t automatically detect, you will have to manually select it by the above path(** Short flow)- instead of option JBL Flip, select wired headset/headphones.

Hope this helps.