Audacity Meter Moves but HDMI Audio Is Silent on Ubuntu: Fix the Audio Host or Replace the Snap

If Audacity's output meter bounces while your HDMI speakers stay silent — and every other application on the machine plays normally — the MP3 file and the GPU are fine. Audacity is delivering its audio to the wrong audio host or the wrong output device. The practical fix on current Ubuntu releases is to open Edit > Preferences > Devices, set Audio Host to PulseAudio, and select the AMD HDMI output under Output Device. If PulseAudio never appears in that dropdown, the copy of Audacity installed from the App Center — a Snap package — is usually the reason, and installing the apt package instead resolves it.

Why the meter moves while the speakers stay quiet

Audacity rarely touches sound hardware on its own. On Linux it hands finished audio to a host — ALSA, PulseAudio, or JACK depending on the build — and the Output Device list is populated by whichever host is selected. The on-screen meter is drawn from Audacity's own output pipeline, so it animates as soon as the program renders samples, whether or not those samples reach an amplifier. A lively meter proves decoding and rendering work; it says nothing about delivery.

Modern Ubuntu runs PipeWire as its sound server, and PipeWire deliberately implements the PulseAudio interface so older applications keep working. Audacity does not need native PipeWire support: with the host set to PulseAudio, audio flows into PipeWire through that compatibility layer and follows the desktop's default device. The usual failure is narrower than "Audacity does not do PipeWire" — a build that hides the PulseAudio host or exposes a restricted device list, often due to Snap confinement. The sound then renders into a host or endpoint you cannot hear, while the meters keep dancing regardless.

Diagnose before changing settings

• Confirm the system path. Play a video in a browser or media player on the same HDMI output. If that works, PipeWire, the driver, and the sink are healthy, and the fault is inside Audacity's configuration.
• Check the default sink. Run pactl info | grep "Default Sink" and confirm it points at an HDMI sink belonging to the AMD GPU.
• Watch the routing live. Install pavucontrol, open its Playback tab, and press Play in Audacity. If no Audacity row appears at all, the program is not traversing the PulseAudio/PipeWire path — a strong hint the host setting or the packaging is wrong.
• Identify the build. Run snap list audacity and apt policy audacity. A Snap installation combined with a missing PulseAudio host option is the pattern that predicts the second fix below.

Fix one: point Audacity at PulseAudio and the HDMI device

1. Open Edit > Preferences and select the Devices panel. The Audio Setup toolbar button exposes the same host and device dropdowns if you prefer switching on the fly.
2. Set Audio Host to PulseAudio. On PipeWire-based systems the entry is still labelled PulseAudio — that is expected; it is the compatibility route into PipeWire.
3. Under Output Device, pick the HDMI output of the AMD GPU. GPUs frequently expose several entries such as HDMI 0, HDMI 1, or DisplayPort, so try each if the first stays silent.
4. Click OK and play the file again.

If PulseAudio is available but still silent, retry with ALSA as the host and select the HDMI device explicitly. That can work, but the ALSA route bypasses desktop mixing: system volume sliders and per-app routing no longer apply, so treat it as a fallback rather than your default setup.

Fix two: replace the App Center Snap with the apt package

When the Audio Host list offers no PulseAudio entry at all, the Snap build is the likely culprit. Remove it and install the distribution package:

sudo snap remove audacity
sudo apt install audacity

With the archive package — version 3.7.7 at the time of writing — the PulseAudio host reappears, the HDMI device becomes selectable, and playback behaves. The trade-off is version drift: the Ubuntu archive may lag behind the newest upstream release the Snap offers. If you specifically want the newest build, install the Flatpak edition from Flathub instead, which typically exposes both the PulseAudio and ALSA hosts, or revisit the Snap after a future refresh restores the host list. Also note that uninstalling the Snap discards its per-application settings, so re-check your device preferences after reinstalling.

Keeping playback reliable

• Leave the host on PulseAudio for everyday desktop use; it follows the default sink and lets pavucontrol redirect the stream mid-playback.
• When a monitor powers down or you dock and undock, PipeWire may switch the default sink. Use the sound settings or pavucontrol to point audio back at HDMI; a PulseAudio-hosted Audacity follows on its next playback.
• Match endpoints: the same AMD GPU can expose multiple HDMI/DisplayPort outputs, so the one enabled in the desktop's sound settings should be the one chosen inside Audacity.

Frequently Asked Questions

Does Audacity work with PipeWire at all?

Yes, indirectly. PipeWire speaks the PulseAudio protocol, so Audacity's PulseAudio host sends audio straight into PipeWire. It also plays through PipeWire's ALSA plugin when the ALSA host is selected, though that path skips the desktop mixer.

Why does the output meter move if nothing is audible?

The meter samples Audacity's own stream as it renders. It validates decoding and output processing, not delivery to a speaker, so a wrong host or device still produces full meter activity with no sound.

PulseAudio is missing from the Audio Host dropdown — what now?

That is the signature of a confined Snap build. Remove the Snap and install the deb with sudo apt install audacity, or use the Flatpak edition; both expose the PulseAudio host.

Should I just use the ALSA host instead?

Only as a fallback. ALSA works when you select the exact HDMI device, but it bypasses desktop volume control and can clash with other applications claiming the device. PulseAudio, backed by PipeWire, is the sane default on Ubuntu.

Do I really have to downgrade from 3.7.9 to 3.7.7?

The version number is incidental; host availability is what matters. A slightly older apt package is harmless for playback, and you can return to a newer build once it offers the PulseAudio host.