My beloved Macbook Pro is making a sound it hasn't before...

I've had my Macbook Pro 13" since around June 2010 (so I've been thrashing it for almost a year and a half).

BUT in the last few weeks, it's started making a sound it never has before. It's low in key, and it's almost like a gentle, slowish rumble or vibration noise (it doesn't actually vibrate, it just sounds like it). It reminds me of having a sore throat, the noise is raspy and...scratchy...or like a tiny dirt bike. There are random moments when the noise is louder and quicker for not more than a second. And then at times it's so quiet, it's almost not there.

It's been the perfect computer since I bought it, quiet, efficient with only the occasional freeze or heat up from having too many programs open at one time. So this is the first thing out of place- I want to make sure I tackle the issue before it becomes a problem. The software is NOT running any slower than usual.

Plus, I've dropped it once, 7 months ago. It didn't seem like any damage had been done. But now there's this noise.

Thanks for any advice you might share.
I really appreciate it

Have you noticed the MacBook Pro getting any hotter in use? It sounds like the fan is not working properly, and I would first check for fluff blocking the airways into it.

Cheers

Hugh

I would suspect the fan either bad or dirty . You could download iStat widget and it would show you fan speed and look at the comparison with and without noise.

Take off the panel on the bottom and have a look for anything extraordinary.

Thanks guys, I'm pretty much convinced it's the fan from my research so far. I have iStat, the fan speed sits on 2000rpm most of the time (I've only been able to check it while my fans been generally quiet).

I'm gonna lift the hood today and give the fan a clean, if that doesn't help- I'll probably take it into the store, computer repairs are pretty cheap here.

Thanks everyone, I really appreciate it.