I got my cats around 7 weeks and neither made much noise until they were 4 or 5 months old. My girl cat has gotten more and more vocal (9 mos old now); now she meows or trills at meal time, when she wants attention, when she is looking for the other cat, feels like being noisy, etc. My boy cat makes a squeaky sounding meow and it's generally only when he thinks I'm taking too long to feed him (the food should be out of the can, in the cat bowl, and served in 10 seconds or less).
I think some cats are just more vocal than others; it's not necessarily a medical issue. I know some cats who meow non-stop and others who don't make a peep. It just depends on the cat.