• MacBook Air, Retina, 13-inch, 2019
  • Running Catalina 10.15.2

  • Using USB-C to HDMI adaptors, MacBook Air sound preference center cannot recognize the device it is plugged to (HDMI cable connects the adaptor to the TV monitor; sound on TV monitors has been tested; older MacBook Pro with HDMI output can output sound just fine);

  • Video is fine
  • Tried with three different USB-C to HDMI adptors: two StarTech and one CLDAY. All are supposed to support audio output
  • Troubleshoot this on two different screens, and two different projectors (hooked to speakers)
  • Troubleshoot while being powered on (i.e. with AC plugged in)

No sound nor device detected (in the sound panel) in every case.

In each case, the sound is being played through the MacBook Air internal speakers.

  • For providing USBC > HDMI, power and USB-A support to the MBAs, the only adaptor which truly works is the USB-C Digital AV Multiport Adapter. We had to make the hard choice to purchase >100 of these to support our users, but no other adaptor worked, worked well, or held up to abuse. If you only need USBC > HDMI, Anker makes a great adapter we use in other locations.
    – IconDaemon
    Commented Jan 29, 2020 at 22:56
  • Thanks for the comment! I read the Anker would provide “Seamlessly display high-quality sound and video through your USB-C port”. I could give it a try. The two other adaptors I tried also advertise sound capabilities.
    – Parneix
    Commented Jan 30, 2020 at 13:41

1 Answer 1


After trying yet another adaptor (the Anker mentioned in the comment by IconDaemon) without success, I restarted the machine to reset NVRAM. It fixed the issue. In System Preference, the Sound panel now recognizes external devices, and sound goes through HDMI regardless of the adaptor I’m using (StarTech, CLDAY or Anker).

  • It’s not a permanent solution though, as the problem seems to reoccured after a while, for reason I can’t pinpoint.
    – Parneix
    Commented Feb 4, 2020 at 21:33

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