---
name: "snd_dummy"
section: "4"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/snd_dummy"
---

# snd\_dummy(4)

Dummy audio driver

## NAME

**snd\_dummy** – Dummy audio driver

## SYNOPSIS

To load the driver at boot time, place the following line in [loader.conf(5)](/loader.conf/5.md):

```
snd_dummy_load="YES"
```

## DESCRIPTION

The **snd\_dummy** driver implements a virtual testing device, meaning it does not correspond to a physical sound card. It is intended for testing, so that test programs do not need to rely on hardware being present in the machine in order to run.

The driver attaches as a regular [sound(4)](/sound/4.md) device, with two channels (one playback and one recording), as well as a mixer.

Playback works by discarding all input, and recording by returning silence (zeros).

## FILES

- */dev/dsp.dummy*

  Alias to the device's */dev/dsp%d* file created by [sound(4)](/sound/4.md). This makes it easy for tests to open the dummy device when there are more devices present in the system.

## SEE ALSO

[sound(4)](/sound/4.md), [loader.conf(5)](/loader.conf/5.md), [loader(8)](/loader/8.md)

## AUTHORS

The **snd\_dummy** driver was implemented by Christos Margiolis ⟨*christos@FreeBSD.org*⟩ under sponsorship from the FreeBSD Foundation.

## CAVEATS

Because the driver automatically attaches once the module is loaded, it can only be attached once.