Introduction
If you’ve ever used Windows, you might have seen the option “Listen to this device” — it lets you hear your microphone or line-in directly through your speakers. On Linux, this feature is called loopback monitoring.
The process varies depending on your audio system — PulseAudio, PipeWire, or ALSA — but all methods achieve the same thing: routing audio from your input to your output in real time.
This beginner-friendly guide will walk you step-by-step through each method, with both command-line and graphical options.
(generated with the help of ChatGPT)
In-Page Navigation
Using PulseAudio
PulseAudio was the default audio server on many Linux distributions before 2022.
Enable Loopback
Open a terminal and run:
pactl load-module module-loopback latency_msec=1This routes your default input to your default output with minimal delay.
Choose Specific Devices
List all devices:
pactl list short sources
pactl list short sinksThen specify them:
pactl load-module module-loopback source="alsa_input.pci-0000_00_1f.3.analog-stereo" sink="alsa_output.pci-0000_00_1f.3.analog-stereo" latency_msec=1Disable Loopback
pactl unload-module module-loopbackUsing PipeWire
PipeWire is the modern default on many distros like Fedora, Ubuntu 22.10+, and newer Arch-based setups.
The good news: PipeWire supports the same PulseAudio commands. You can use:
pactl load-module module-loopback latency_msec=1Visual Connection with Helvum
- Install Helvum:
sudo apt install helvum # Debian/Ubuntu
sudo dnf install helvum # Fedora- Open Helvum
- Drag a cable from your input device to your output device
- Done — live monitoring activated.
Using Pure ALSA
If you’re running ALSA without PulseAudio or PipeWire, you can still monitor audio.
Basic command:
arecord -f cd - | aplayLower latency:
arecord -f cd --buffer-size=256 - | aplay --buffer-size=256You can also specify devices with -D hw:1,0.
Graphical Tools
If the terminal feels intimidating, you can achieve the same with GUIs:
- pavucontrol (PulseAudio Volume Control) → Input Devices tab → Enable Monitor or Loopback
- Helvum (PipeWire) → Drag-and-drop audio routing
- Cadence / Catia (for JACK users) → Connect devices in Patchbay
Final Tips
- For the lowest delay, experiment with
latency_msecor ALSA buffer sizes. - Use headphones when monitoring to avoid feedback loops.
- If you only need to check sound occasionally, unload the module to save CPU.
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