Noise issue from heck!

Hi there!
This is what's going on. A little more than a week ago the chain broke on my flapper and I replaced it. After I replaced it, when you flushed the toilet you had to hold the handle down, it wouldn't 'float' around while the toilet filled up. Since then, once in awhile my wife and I have noticed a strange humming sound. It would go away and we never put two and two together, until tonight. The sound is really loud and continuous now and I've noticed when the toilet is refilling after a flush, the noise stops. Also if I turn the water on in the bathroom sink, the sound will go down a little, but of course come right back when I turn the water off. I've checked the valve for the water going into the toilet and made sure it was on full, but whether it's on full or completely off the vibrating/noise is still happening. It's very low pitched and really annoying me (and my cats). Any suggestions for this problem would be GREATLY appreciated.

A. Flapper - Shorten the chain on the new flapper to where it just allows the flapper to fully seal when down.
B. Noise - Install a new Fluidmaster 400A float-cup type toilet tank water valve assembly (about $6 bucks at a big box). Just follow the illustrated directions that come with it. Easy.
Should solve your problems.
Good Luck!
Mike

noise

The flapper must not be seating, and if it does not stay up you may have the wrong one or installed it wrong, (probably by sliding the hole over the overflow pipe and then also connecting the two holes to the ears on the flush valve). You must also have a "float ball" type fill valve.

hj is right. I forgot to mention to cut-out the ring that goes on the overflow pipe and just use the little rubber "ears" of the flapper on the two L-shaped brackets on the bottom of the overflow. Works much better that way.
Mike

Gentlemen, all your help is so appreciated and I'm very grateful! I was wondering when installing the flapper why it was so hard to slide down that pipe ...the noise is gone! You are all rockers!