Sound on MathLAN Workstations
Sound is available through headphones through most MathLAN workstations. However, sometimes the audio setting is muted, and sometimes sound comes through the workstation's speaker, rather than through headphones.
Getting started adjusting workstation sound generally begins the same, regardless of the details of the trouble.
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In a terminal window, type
alsamixer
A graphical interface appears in the terminal window, with a vertical column showing an overall volume setting.
The following approaches address various problems. The narrative that follows progresses from the simplest fixes to those requiring several potential steps.
No Sound, Either from Speakers or Headphones
The following assumes that you have started alsamixer within a terminal window.
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If MM appears in the small box at the bottom of the vertical column, sound has been muted. Press m on the keyboard to enable sound. (The m is a toggle setting; pressing m multiple times successively enables and disables sound.
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Once sound is enabled, the sound level is shown for the left and right channels at the bottom of the interface, with numbers between 0 and 100 just above the line that reads "Master".
- Use the number keys (e.g., 1, 2, 3, ..., 7, 8, 9) to set both channels (e.g., to 10, 20, 30, 70, 80, 90).
- Use the up-arrow and down-arrow keys to increase or decrease the audio level with finer-grain control.
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Press Esc, the Escape key, to quit the alsa mixer.
Sound from a Workstation's Speakers, rather than from Headphones
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With the alsamixer interface open,
- press the F6 button to "Select Sound Card",
- use the down-arrow key to highlight option "0 HDA Intel PCH"
- press return
A extensive display of devices should be displayed; the bottom of the display will show various sound channels e.g., Master, Headphone, Headphone, .., Speaker, PCM, ...). Above most channel labels, a graphical sound level is shown.
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When first displayed, the left controller (the Master) is highlighted. Using the same directions from Steps 2 and 3, be sure this Master volume control is not muted and shows a reasonable volume level (e.g., 70).
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Use the right arrow (or left array) to move to a Headphone channel that has a vertical volume bar. (A square with MM or 00 does not seem necessary.) Likely this channel will be the right-most Headphone channel. With this channel, use the up-arrow and down-arrow to set a comfortable sound level.
Following a similar approach, use the right arrow to select the PCM channel, and set that volume as well (e.g., to 70 or 80).
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To avoid distracting your neighbors, disable the speaker by using the left/right arrow to select the Speaker channel, and type M to mute the speaker.
When Done Adjusting Volume
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After the workstation's speaker is turned off, and the headphones are set at a reasonable volume, press the Escape key (Esc) to exit the alsamixer.
