Amazon Echo Dot 仅显示为输入设备，而非输出设备

Question

我在台式电脑上安装了 Ubuntu 18.04.4 LTS，还有一台亚马逊 Echo Dot。我的桌面通过蓝牙与 Echo Dot 通信，并成功连接。这是正在使用的蓝牙适配器。问题是 Echo Dot 显示为输入设备（录制我的声音），而我无法让它作为输出设备（播放来自我电脑的音频）。Echo Dot 能够通过蓝牙毫无问题地播放来自我手机的音频。我还尝试将我的无线耳机连接到桌面，并且能够通过耳机播放来自桌面的音频。

下面粘贴了一些来自终端的信息文本（或者至少我希望如此；我是 Linux 新手）。我尝试安装 Blueman 并将其与音频接收器配对。即使忘记了设备并重新连接，这仍然无效。我似乎无法让此设备播放来自我电脑的声音。请帮忙！

pactl list short sinks
5   alsa_output.pci-0000_00_1b.0.analog-stereo  module-alsa-card.c  s16le 2ch 44100Hz   RUNNING

pacmd list-cards
....
    index: 3
name: <bluez_card.CC_9E_A2_15_EC_BA>
driver: <module-bluez5-device.c>
owner module: 27
properties:
    device.description = "Echo-X8G"
    device.string = "CC:9E:A2:15:EC:BA"
    device.api = "bluez"
    device.class = "sound"
    device.bus = "bluetooth"
    device.form_factor = "speaker"
    bluez.path = "/org/bluez/hci0/dev_CC_9E_A2_15_EC_BA"
    bluez.class = "0x2c0414"
    bluez.alias = "Echo-X8G"
    device.icon_name = "audio-speakers-bluetooth"
profiles:
    a2dp_source: High Fidelity Capture (A2DP Source) (priority 20, available: yes)
    a2dp_sink: High Fidelity Playback (A2DP Sink) (priority 40, available: no)
    off: Off (priority 0, available: yes)
active profile: <a2dp_source>
sources:
    bluez_source.CC_9E_A2_15_EC_BA.a2dp_source/#4: Echo-X8G
ports:
    speaker-output: Speaker (priority 0, latency offset 0 usec, available: no)
        properties:

    speaker-input: Bluetooth Input (priority 0, latency offset 0 usec, available: yes)
        properties:

set-card-profile 3 a2dp_sink
Failed to set card profile to 'a2dp_sink'.

我已经检查过这个类似的问题。不幸的是，解决方案对我来说不起作用。