A fairly expensive Shure vocals dynamic (coil and magnet) microphone messes up its frequency response with a peak at mid-high frequencies.
They claim it makes vocals have "presence" (sound closer).
I think today it makes a shriek sound. You know how some singers sound like they have a whistle stuck down their throat?
Maybe it was designed a long time ago to help an AM radio announcer or singer sound clearer.
At the time I was looking through a catalogue for small dynamic mics as used in cheap applicances, cellphones, headsets etc and there hundreds of mics all with little charts, and none of the charts looked good.
A dynamic mic is like a little speaker. It has a magnet that has a moving coil around it to generate a signal. The coil is fairly heavy so it needs a fairly strong and heavy diaphragm to move it with sounds so its resonance is at a few thousand Hz which causes a peak in the response.
But an electret mic has a very thin and lightweight conductive film as its diaphragm so its upper frequency response is extended and is flat.