Are your headphones on backwards? Is it too dark, or too inconvenient to physically check?
Use Stereo Test to quickly verify that you're getting the correct audio channel sent to each ear or speaker. Hear your music & video how it was supposed to be heard: Left-left; Right-right.
TAGS: stereo test, audio test, sound test, headphone test, stereo check, audio check, sound check, headphone check, stereo, headphones, channels, left channel, right channel, two channels, channels reversed, identify channels