A basic but common question that you might be wondering when watching a DJ do his/her work is why they are wearing headphones. It's interesting to see a DJ playing music but then have headphones on at the same time and there is a specific reason for this that we will cover here today. 

When DJs are playing music and mixing songs together they use the headphones they are wearing on their head to take a brief listen in order to cue the following song they are going to play next in line. This song has to mix well with the current song that is being played so some DJs will try to find a song with the same tempo or they will actually temporarily change the tempo of a song so they mix well and then as the second song comes into full volume and the first song goes to zero volume they will gradually change the second song's tempo back to it's original. This creates a proper and seamless transition from one song to the next and most of the time the audience has no idea because it is done so smoothly by the DJ playing the music behind the sound board and mixer. 

When wearing headphones the DJ is allowed to test certain songs to see how they match up against the current songs that are being played in order to see if they would be a good fit for the next song. Sometimes a DJ might have 5 or 6 songs lined up and he can use the headphones to listen to each one of those songs in order to line them up accordingly so they are all prepped and ready to go. Another option is that if a DJ has never heard a song before that he is going to play he can test it in the headphones to make sure it is going to be appropriate for the audience he is working for. This might happen at a wedding or school dance here someone approaches the DJ to play a specific song for them but the DJ has never heard that song before. The DJ can't and shouldn't always play songs that are recommended but there are times that it fits well and he or she will play a recommended song. Especially if the song is well known and maybe the DJ planned on playing it anyways then it would be an easy fit for him or her to play the song that is being recommended by one of the people attending the event and enjoying the music. 

When you see a DJ wearing headphones you will notice that one ear is covered while the other ear is not. There is a specific reason for this as well. If you were to ask a DJ why they only listen to the headphones with one ear and not both of them, they would most likely tell you this answer with confidence: the reason why I only listen to the headphones with one ear listening to them and one ear not is because when I am up at the DJ table and playing music I want one ear to be listening to the music that is coming out of the speakers and the other ear able to listen to the music in the headphones. This helps a DJ determine how the two songs fit together and if they need to match the tempo of the songs together they can do that easily while wearing the headphones like this.