Technically, background sounds disrupt concentration. Contrary to popular belief, no one can truly "multitask" (do two or more things exactly simultaneously). The human brain isn't wired that way. When there are other sounds or commotions in a room, the brain will constantly switch back and forth from the task at hand to the disruption, thus disrupting full concentration. Problem is most people don’t spend their life in total silence. So how can they ever concentrate? The brain is also wired to filter out unwanted sounds. Ever tried talking to someone in a noisy room (such as at a party or theater)? How is it that you can hear the person you’re talking to and not every conversation in the room? The brain is also wired to filter out extraneous sounds. That’s why you can also pick out other (local) conversations in a noisy room as well. You have to concentrate harder to eavesdrop on a conversation, but it is possible. Of course, when you’re reading or studying, your concentration is on what you’re doing – not on eavesdropping. This is where background sounds like white noise or music can help. These sounds, set at a certain volume/frequency, can actually cancel out other undesirable sounds like traffic, dogs barking, or loud neighbors. Not everyone’s brain is wired the same. While the brain tries to filter out superfluous sound, some people have a harder time at it than others. These people usually like total silence when they’re trying to concentrate.
However, there may be more to playing music in the background than simply filtering out unwanted sounds.
“Music hath charms to soothe a savage breast”. - William Congreve
Many people find music (of their liking) to be soothing and comforting. Playing background music can help a person relax, and relaxation helps focus concentration.
“Music does a lot of things for a lot of people. It's transporting, for sure. It can take you right back, years back, to the very moment certain things happened in your life. It's uplifting, it's encouraging, it's strengthening.” - Aretha Franklin
Music has a strong connection with memory. Hearing a certain song or even hearing certain chords can bring up vivid memories that one thought were long gone. I’m sure that there are songs that when you hear them you’re instantly transported back in time to when you first heard them or when they were playing at a special event (to you).
It’s a known fact that if you want to learn something, put it to song. How many times do you go around singing sing “happy birthday to you” or “twinkle, twinkle little star”? I’m willing to bet that just seeing those words brought back the entire songs words and melody. The same is true for some background music. When played, it can help one memorize things better and, when sung back, can help to recall information better.
Shuhak 