These are not recordings of the songs. Rather, they are MIDI: digital music. Your computer's sound card will do its best to faithfully play the song. However, it may sound radically different from what you remember. That's part of the challenge!
This game uses the built-in MIDI file player in your web browser. I recommend Firefox (totally free, blocks pop-ups and annoying images, and is more configurable than IE).
There are 82 possible songs. The song to play and the 3 wrong answers are random each time. Never the same question twice!
Some songs are better programmed than others. Some sound cards do a better job playing them than others. That's just life.