I have experienced that when my tensioner went out the timing belt was much louder ticking noise than the valves AND it would go away at around 1,700-2,500 RPM and higher (if I recall correctly) AND It'll always be there until you of course replace the tensioner.

If it's the valves then it should go away sometime during the day either when the engine has warmed up or has cooled down.. since I haven't really figured out and rhyme or reason for when they start making their noise.

So if the noise is constant and goes away when you rev the engine it's probably the tensioner. If it's the valves it'll be random.