Music and sound will probably make about 20-60% of the feel of the game, dependant on the type and style of the game of course. Heavy action games like Quake three, probably the music will have very little impact, but the sounds do add to it. Maybe a good 25% in Quake three. In RPGs, music is often to most looked for in heavy RPGers. Music has the biggest impact on games I feel, often heavier than graphics. Well, with good music, you need a good story or feel to the game. If you have good music, but not a good story or feel, then the music won''t bring out anything decent.
Ever buy the soundtrack to a movie? Most people don''t realize there''s even music in the movie unless there''s a quiet spot or area where the music is intended to be heard. That''s exactly what the composers want. Go straight to the subconcious, because the concious already has a million things to pay attention to. It''s the same with games.
Sound effects build nicely on the atmosphere, but only if their good. Poor or redundant sound effects can shred a game in no time flat. *Tries to think of an example...* Well, I never really payed attention to SFX myself, however
Vocals are a whole different thing, even though I like to classify them as sound effects. But they are extremely powerful in things such as plot twists, or dramtic scenes. Also, it helps clerify, because a good amount of communication (20% to my guess) is in the tone of voice and how something is said. Sarcasms, seriousness, humor, anger, all those attributes are extremely hard to bring out in text alone. However, when SFX isn''t an option (older games, IRC, etc.), they are simulated with "...", "*sigh*", "
" or anything else. But it''s not nearly as effective. Now, if you do have vocals, then you maybe have %60 of the communication. Body language probably plays the rest (ever go to a class on communication, anthropology (sp), or lingusitics? They all say pretty much they same thing). But that''s a different matter, and it takes an unbelievable amount of detail to work in a game. Not to mention putting it in, because to be honest, your concious doesn''t know how to say things with body language or what tone to put them in.
Eh, I said enough for now. Just now had a few moments to spare