While effective during Skype voice communication, your computer's microphone -- whether it's an internal model or an external USB headset -- makes an ineffective broadcasting source when it's held up against another speaker. Even if you don't notice a decrease in sound quality, there's always the potential of annoying audio feedback. To share the playback of sound during a Skype call, it's more effective to reconfigure your system's sound input settings so your Skype friends end up hearing what you hear over your computer speakers.
Provided your computer's sound card supports it, a Windows machine can share audio by way of an entirely software-based solution. To achieve it, simply enable "Stereo Mix" as the recording device in the system's sound settings. Unfortunately, the same doesn't apply to a Mac, nor is there an effective platform-based solution if your PC's sound card isn't designed to support "Stereo Mix." In this event, purchase an inexpensive auxiliary cable and go with a simple, hardware-based solution instead.
Stereo Mix in Windows
If you're running Windows 8.1, first determine if your machine supports the "Stereo Mix" recording device setting. Begin from the Windows Start screen and type “sound." Select "Settings" from the search results, and then choose the "Sound" option and switch to the "Recording" tab in the window that appears. The feature is disabled by default, so right-click anywhere within the list of recording devices and click to enable both "Show Disabled Devices" and "Show Disconnected Devices." Select "Stereo Mix" -- which should now appear in the list of available devices -- and enable it.
When Stereo Mix Is Missing
If the "Stereo Mix" option is still missing from the list of available devices, try updating your audio drivers next. From the Start screen, type "device manager," and then select Device Manager from the available search results. Expand the "Sound, Video and Game Controllers" category and double-click on your sound device. In the window that appears, select the device's "Driver" tab and then click "Update Driver" to search for available driver updates. If no update is available -- or "Stereo Mix" remains missing even after an update -- your sound card simply doesn't support it.
An auxiliary cable can solve the problem if you have a Mac -- or if your PC lacks "Stereo Mix" support. Plug one end of the cord into the music source's headphone jack -- whether it's your iPod, smart phone or the computer itself -- and then plug the other end into the computer's microphone input jack. Switch the recording device -- launch System Preferences and open the "Sound" option on a Mac -- so "Line In" is your default device instead of "Microphone."