The bulk of Regular 8, 16mm and super 8 films have no sound. The super 8 was the latest format and it had no audio until 1973. By the way, you can tell if a film has sound because the film features a magnetic tape that looks like a thin copper strip running along one edge. It was a big deal when sound film came out in 1973, but it was short lived.
A few years after the release of super 8 sound tape, VHS technology was introduced. VHS stands for Video Home System. This was a new type of video tape. VHS was released in June 1977 in the USA. As soon as it released, everyone started buying them instead of buying super 8 sound recorders. This is the reason why you can not see a host of super 8 sound film. The introduction of latest VHS tapes changed the trend in the society at that time and people turned to VHS instead of Super 8.
So, if you want to transfer your super 8, 8mm or 16mm movies to DVD, chances are your old home movies have no sound. These silent home movies have their own charm. However, it enhances the emotional experience of watching your old home movies when there's background music added to your silent films.
Choose a music genre that's easy to listen to and will work well for varied scenes. Stay away from rock 'n roll, or other strong-beat music that may not be appropriate to go say, with peaceful scenes of swimming in the lake. Classical music is popular as background music to silent films, but even then you have to be selective, go with popular light classic as opposed to Shostakovich dissonant cords.
If the film transfer lab offers to add background music at no charge, do it. If you decide you do not like the music, you can always mute it. Although the chances are that the lab will use time-tested music choices and you will enjoy watching your old silent films with a emotion-evoking background music.
If you choose to transfer you home movies onto a computer hard drive (as quicktime or avi files), then do not add background music. This is due to the bulk of customers who transfer their 8mm, super 8 or VHS films onto a PC HD do so in order to edit the videos. The purpose of editing can be to trim out some sections, add titles or transactions. At that point, you can add background music of your choice.