我认为不必加the。正确说法：I'd like to sing in music room. 因为在陈述，没有强调在哪里的意思。比如，I will eat at home.也不用加the.
在音乐教室里： in the music room I'd like to sing in the music room.我想在音乐教室里唱歌, 没有错.
