Dell Inspiron 17 (7737, Mid 2013) - Manual (Page 39)

Speakers
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Speakers
Laptops and tablets have built-in speakers for audio output. Desktops also
have a built-in speaker, however, they are used only to produce beeps to
indicate errors or failures.
You can also connect external speakers to your computer or tablet.
Speakers may support 3.5 mm audio connector, USB, or wireless connection
to your computer.
Speakers are generally categorized by the number of audio channels
they support; 2, 2.1, 5.1, 7.1, and so on. The digit before the decimal point
indicates the number of channels and the digit after the decimal indicates
the sub-woofer.
NOTE: Your sound card and speakers must support 5.1/7.1 channels for
producing 5.1/7.1 channel audio.
2.1 Audio
2.1 refers to a system with two speakers (left and right channel) and one
subwoofer.
5.1 Audio
5.1 refers to the number of audio channels in most surround-sound
configurations. A 5.1 audio system uses five main audio channels (front left,
front right, center, left surround, and right surround) and one low-frequency
audio channel.
7.1 Audio
7.1 refers to the number of audio channels in high-end surround-sound
configurations. A 7.1 audio system uses two additional speakers (rear left and
rear right) in combination with the 5.1 audio system. For more information
on setting up audio see
“Setting up Audio” .