In music production . The music engineers are usually referred to as sound engineers. Why?

In general terms, a sound engineer is someone responsible for some aspect of the sound at live shows. Many people think of the sound engineer as the person who stands behind the big sound desk (aka mixing desk) at a show and mixes the sound the audience hears, also known as front of house (FOH) sound. There are other roles for sound engineers at shows, however:
•A monitor sound engineer takes care of the sound the band hears in their monitors on stage. If you're ever heard a band say, "can you turn down my guitar a little bit" or something similar, they are talking to the monitor sound engineer.
•Systems engineers take care of setting up amps, PA, speakers and such for the band and the other sound engineers.

~ Sound engineers don't have to work strictly in music. Some engineers end up doing sound at conferences, for speeches and any other venue that requires projection of sound for an audience.
Hope this helped u :D
~ Sarah :) ~