Could be so many things from a dead bug in the voice-coil to a blown speaker to any of a dozen other causes. If you can feed the speaker from another source and if *does not* scratch, you have a problem with the head-end (electronics). If it continues to buzz, it is the speaker. Before replacing it, try removing it from the vehicle and blowing it out with canned air (NOT compressed air - far too powerful), paying attention to the voice coil below the spider. If crud gets in there, that will cause the buzz. Also gently press the cone in - do you feel any scraping? If so, the speaker is done.

Parts Express will sell you speakers in many configurations, sizes and styles. Something will fit. Keep in mind this is a Camry. Which is a not-particularly sound-proof device, and within which speakers are more noisemakers than high-fidelity audio reproducers. What you will need to do is pay attention to polarity when you install the new speaker.

Good luck with it.

Peter Wieck
Melrose Park, PA