Sounds like you are making that sound to close your epiglottis while you equalize, to do a frenzel (just a guess). I had to do a similar thing when I was first learning it. But with time I learned to equalize with out it.
You might try some equalisation training with empty lungs just on a shallow pool. Empty our lungs, fill your mouth on the surface and once you drop down , try to equalize with the air in your mouth. First with the sound, then without it. At first, do it feet first (so you can concentrate just on the equalization), then head first...
Nothing to be ashamed of, at least it's more original than most divers
