How to adjust Audio Levels in Ubuntu

Posted on 7:41 PM by Bharathvn

The command line audio tools you use to enable audio devices and adjust audio levels
depend on the type of audio system you use. Advanced Linux Sound Architecture
(ALSA) is the sound system used by most Linux systems these days. The Open Source
Sound System (OSS) has been around longer and is still used on older hardware. In general, you can use alsamixer to adjust sound when ALSA is used and aumix with OSS.
ALSA is the default sound system for many Linux systems. By adding loadable modules that enable OSS device interfaces to work as well, audio applications that require the OSS device interface can work with ALSA as well. To see if OSS modules are loaded, such as snd-pcm-oss (emulates /dev/dsp and /dev/audio), snd-mixeross (emulates /dev/mixer), and snd-seq-oss (emulates /dev/sequencer), type:

# lsmod | grep snd

If the modules are loaded, you can use alsamixer to adjust audio levels for OSS sound
applications. Start alsamixer as follows:

$ alsamixer Show alsamixer screen with playback view
$ alsamixer -V playback Show only playback channels (default)
$ alsamixer -V all Show with playback and capture views
$ alsamixer -c 1 Use alsamixer on second (1) sound card

Volume bars appear for each volume channel. Move right and left arrow keys to
highlight different channels (Master, PCM, Headphone, and so on). Use the up and down
arrow keys to raise and lower the volume on each channel. With a channel highlighted,
press m to mute or unmute that channel. Press the spacebar on a highlighted
input channel (Mic, Line, and so on) to assign the channel as the capture channel (to record audio input). To quit alsamixer, press Alt+q or the Esc key. Press Tab to cycle through settings for Playback, Capture, and All.

The aumix audio mixing application (for which you need to install the aumix package)
can operate in screen-oriented or plain command mode. In plain text you use options
to change or display settings. Here are examples of aumix command lines:

$ aumix -q Show left/right volume and type for all channels
$ aumix -l q -m q List current settings for line and mic only
$ aumix -v 80 -m 0 Set volume to 70% and microphone to 0
$ aumix -m 80 -m R -m q Set mic to 80%, set it to record, list mic
$ aumix With no options, aumix runs screen-oriented

When run screen-oriented, aumix displays all available audio channels. In screenoriented mode, use keys to highlight and change displayed audio settings. Use PageUp,PageDown, and the up arrow and down arrow keys to select channels. Use the right or left arrow key to increase or decrease volume. Type m to mute the current channel. Press the spacebar to select the current channel as the recording device. If a mouse is available, you can use it to select volume levels, balance levels, or the current recording channel.