Why does my acoustic guitar buzz on certain frets?

"Certain frets" is actually a huge clue. If your guitar buzzed everywhere, uniformly, I'd ask about action height and call it a day. But buzz that shows up on specific frets, and not others, means something in the neck or frets isn't flat and consistent — and that's a completely different conversation.

Uneven fret height or neck relief

The most common culprit. If one or two frets are slightly taller than their neighbors — from wear, a botched fret job, or just manufacturing variance — the string will buzz against them before it even gets close to the higher frets down the line. A neck with too little relief (too flat, or worse, back-bowed) creates buzz in the middle of the fretboard specifically, because there's no clearance for the string's vibration arc.

A high fret is not the same problem as low action

People conflate these constantly. Low action buzzes everywhere, evenly, and gets better as you raise it. A high fret buzzes at a specific location no matter how high you raise the action overall, because the problem isn't clearance — it's that one point on the neck is taller than it should be.

How to actually check

Fret a string, then tap along the neck watching (or listening) for exactly where the buzz starts. If it's isolated to one or two frets, that's a fret-level issue, and it usually gets fixed with a fret level, not a truss rod adjustment. If it's spread across a section of the neck, that's more likely relief.

Don't chase this one with random truss rod turns. You can make it worse, and a neck that's been over-adjusted to mask a fret problem is a bigger headache than the buzz ever was. Bring it in and we'll find the actual spot instead of guessing.