I have an Amazon Echo and a laptop running Ubuntu 16.04.1. I can successfully pair the device via Bluetooth (the Echo says Now connected to <my machine's name>), but when I test the sound, nothing is heard. The volumes are high enough and other devices can connect to the Echo just fine.
Here's the dmesg output:
$ dmesg | grep -i blue
[ 12.419477] Bluetooth: Core ver 2.21
[ 12.419491] Bluetooth: HCI device and connection manager initialized
[ 12.419494] Bluetooth: HCI socket layer initialized
[ 12.419497] Bluetooth: L2CAP socket layer initialized
[ 12.419502] Bluetooth: SCO socket layer initialized
[ 12.473236] Bluetooth: hci0: read Intel version: 370810011003110e00
[ 12.480889] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[ 12.839251] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[ 13.386452] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[ 13.386456] Bluetooth: BNEP filters: protocol multicast
[ 13.386460] Bluetooth: BNEP socket layer initialized
[ 16.473284] Bluetooth: RFCOMM TTY layer initialized
[ 16.473292] Bluetooth: RFCOMM socket layer initialized
[ 16.473297] Bluetooth: RFCOMM ver 1.11
[10944.651128] Bluetooth: hci0: read Intel version: 370810011003110e00
[10944.651133] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[10944.977821] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[24061.878085] Bluetooth: hci0: read Intel version: 370810011003110e00
[24061.887184] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[24062.211121] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[24072.874829] Bluetooth: hci0: read Intel version: 370810011003110e00
[24072.874835] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[24073.196858] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[45209.076985] iwlwifi videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 serio_raw videobuf2_core btrtl btbcm btintel input_leds bluetooth snd_hda_codec_realtek(OE) snd_hda_codec_generic(OE) snd_hda_codec_hdmi(OE) v4l2_common snd_seq_midi joydev cfg80211 snd_seq_midi_event videodev media snd_hda_intel(OE) snd_hda_codec(OE) snd_hda_core(OE) snd_hwdep lpc_ich snd_pcm snd_rawmidi shpchp snd_seq mei_me mei snd_seq_device snd_timer snd elan_i2c int3403_thermal 8250_fintek soundcore 8250_dw i2c_designware_platform dw_dmac snd_soc_sst_acpi i2c_designware_core dell_smo8800 dw_dmac_core processor_thermal_device spi_pxa2xx_platform int3402_thermal int3400_thermal int340x_thermal_zone acpi_thermal_rel intel_soc_dts_iosf dell_rbtn acpi_als mac_hid acpi_pad kfifo_buf industrialio parport_pc ppdev lp parport autofs4
[55174.636122] Bluetooth: hci0: read Intel version: 370810011003110e00
[55174.646073] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[55174.970198] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[55181.295879] Bluetooth: hci0: read Intel version: 370810011003110e00
[55181.295922] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[55181.670006] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[56551.946597] Bluetooth: hci0: read Intel version: 370810011003110e00
[56551.955475] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[56552.282610] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[98502.038807] Bluetooth: hci0: read Intel version: 370810011003110e00
[98502.038816] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[98502.356833] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[107908.657215] Bluetooth: hci0: read Intel version: 370810011003110e00
[107908.657298] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[107908.985251] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[109042.464364] Bluetooth: hci0: read Intel version: 370810011003110e00
[109042.464372] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[109042.782838] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[109052.807963] Bluetooth: hci0: read Intel version: 370810011003110e00
[109052.807968] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[109053.127969] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[127570.876446] Bluetooth: hci0: read Intel version: 370810011003110e00
[127570.953632] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[127571.270715] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
I also have this problem. Pairing and sending audio to other bluetooth speakers works. Pairing works to Amazon Echo but no sound is ever heard. I am using Ubuntu 16.04 LTS (Xenial), which was upgraded from 15.10 today (Wily) which in turn was upgraded from 14.04 LTS (Trusty). (I mention this as I wonder if the problem may be specific to upgrade paths vs. fresh installs.)
I believe the problem is related to the fact that pulseaudio pairs the device as a headset rather than just a speaker. This requires a2dp, and that, for me, appears to be where the failure is occurring.
For example, when I pair to my Bose SoundLink II (which works and has since 14.04), dmesg shows:
HOWEVER, when I pair to my Amazon Echo, dmesg reports:
The key line in the above output is the first one, where a2dp reports that the device or resource is busy.
I've hunted around to find a resolution, but so far no luck. The answer proposed by MrUser in discussion found at Question #440386 suggests that the problem may be related to "...a2dp was moved out of the BlueZ stack and into GStreamer" and that he found some success by compiling pulseaudio 5.x himself. However, Ubuntu 16.04.2 LTS uses pulseaudio 8.0, not 5.x and, moreover, the error message above suggests pulseaudio on my system does support a2dp but that a2dp for some reason cannot access the device after bluetoothd has connected it.
This leads me to believe the problem might be due to some problem with permissions or access, but I cannot be sure.
The discussion found at Question #763539 and elsewhere suggest that switching to HSP/HFP mode and then back to A2DP mode resolves the problem, but that is for KDE (i.e., Kubuntu). I have tried to using the a2dp.py script provide by @pylover posted there. It runs fine, but the a2dp "device or resource busy" error still occurs and the problem is not resolved.
If can find time, I will turn on Bluetooth Debugging (as described on Ubuntu's Wiki) and report back what I find. My sense is that this problem can be fixed and that the issue is a simple one, but precisely tracking down the point of failure and making a correction is non-trivial.
If anyone else has insights into this problem and possible resolutions, I'd be most grateful to hear.
The solution I found was in sound settings. At first, I could connect, but no sound. In the sound settings, I changed the 'output device' drop-down box to the default, then back to my Echo manually. YouTube video clicked right in.