Do musical instruments fill in with notes that are in the current chord being played? for example: 8 quarter beats of Cmajor guitar chord, while a fill with a piano is playing notes of the c major chord in the background. Also does the background instrument have to play only the notes in the chord thats current? or can it play some other notes, but just land on one of the chord tones of the current note? One more question, how do you fill with backing instruments if the chord is not a block chord, and if its not playing currently, but will play again without another chord change taking place before it reappears or even after another chord change. Like a guitar chord being played but then it rests for a 9 quarter rest, what fills do you put in, because there isnt a chord sounding, do the fill notes, still play chord tones of the chord before the rest? or does it just play notes of the scale? and what does it resolve to-a chord tone and if so, which chord, the one before it or after or just even a new chord, but how would you outline a new chord while playing solo, without using a block chord and a broken one, just curious about that. Thank you
That would be restrictive - and boring! In 4/4 time - the most common, beats 1 and 3 are often empahsised more, and the chord tones fit better on them. That's a generalisation, and there are many great songs that don't follow that idea.Depending on context, words, and all sorts of other factors that occur in songs, there are no hard and fast rules. Although some non chord notes fit better. On C, D, A and B can often be added as well - in fact, each makes another chord - Cadd9, C6 and Cmaj7 respectively.
Suggestion - look at lots of songs, and take a bar at a time. Establish the chord on a bar, work out its make-up, and see what notes are used over it, and where each chord tone and non-chord tone is put. Bear in mind that the preceding and following bars have a bearing on the bar in question.
Even when looking exclusively at accompaniments, something like a "walking bass" would be nigh impossible if you had to constrain yourself to in-chord notes. There is a focus on in-chord notes, and that focus is a bit stronger the more exposed a note is (by being on the accented beats or by standing out as the only note(s) played at a time or being syncopated or accented or other things).
But playing only in-chord notes as a way to be in harmony is about as useful as hinting at interest in another person by staring him or her in the face wide-eyed and without interruption. It's sort of brutish and does not really add anything to the interaction.
If I understand your question, you're asking whether instruments only play chord tones during songs. So, for example, if the guitar is playing C major, does the piano only play the notes C, E or G?
The answer is probably style dependent, but I'd say it is almost always no. They are not restricted to chord tones. The best example for this is the melody of a song. If you pick pretty much any modern pop music (or music in general), the melody is not restricted to the chord tones. The same principle applies to any fills, countermelodies, or riffs. For example, try playing B C G as crotchets (quater notes) over a C major chord. The B is not a chord tone, but it sounds quite nice (to me, at least). For an example of an actual song using that pattern, see the chorus of Defying Gravity. There are many more examples, but that one springs to mind right now.
That being said, you can't just play any notes. Most of the time, you're going to want to stick within the key of the overall piece (again, this depends on style). And you will often want to start a bar with the chord root in the bass.
Can I suggest transcribing a few songs, or parts of them? Choose a song that you like, and figure out what the notes are for the different parts. Write them down, if you can. It's a good way to figure out how a song works, and what sort of notes it uses.
There are no hard and fast rules here. You're going to have to experiment. That's the fun bit.