What if you have two sound devices? In alsamixer, hit F1. This displays basic commands. F2 displays various /proc/asound outputs related to sound all in one screen. Figure 3 shows I have two sound devices, 0 and 1. F1 takes you back to the menu, and the Return key closes it. To configure the second sound device, close alsamixer by hitting the Escape key, then reopen it like this:

$ alsamixer -c 1

-c means card number. A quick way to test your sound is with aplay:

$ aplay -d plug:dmix yoursoundfile.wav

When you have multiple sound devices, your various applications (such as Skype and Ekiga) should have their own configurations for which devices they'll use. Next week we'll learn how to test individual channels, and how to use the recording functions for various tasks.

Resources

• man alsamixer
• video4linux wiki
• ALSA, with lots of helpful documentation
• Linux Audio Users Guide

Carla Schroder is the author of the Linux Cookbook and the newly-released Linux Networking Cookbook, and is a regular contributor to LinuxPlanet.

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