Foghorn noise made by toilet. Remedy?

Remove the toilet tank lid and see if your fill valve looks like the image below then follow Tom’s advice in post #7, if not get back to us, Thanks.

John

Ahhh! The dreaded toilet monster that roars when flushed complaint. OR the audio message that's sent to the public every time you flush.
Don't mind me. You're my first answer this morning and I'm just having a little fun.
Seriously folks, the noise you hear is caused by the vibration in the stem and washer assembly. Shut the water off under the tank and remove the three screws securing the top of the ballcock. Pull the float ball andstem and washer assembly up and out. Pry the washer out and turn it over pressing it in in firmly. Place your hand over the open ballcock and reach down and turn the water back on to flsh out any crud that might be in there. Reassembly and give it a test flush. Sound better now? Regards, Tom