As an employer, I always look at the hobbies and interests section. The more individual or unusual items often cause me to look more favourably on an applicant - it shows they take an interest in the world, can apply themselves without constant supervision, can think independantly, intereact with other people in some capacity and like being occupied. All of that means they are likely to be an asset to my business. I don't need to know anything about their particular interests - only that they have some. Put your singing down and if asked about it at an interview be proud of it (without going overboard!) to show your interest is genuine, not just something you put down to fill the space on the form. Good Luck!