Dog Grooming Clippers

Question
I have several English Cockers and their hair is matted and clumped.  I have tried using clippers several in fact and it won't cut through the mats.  Which type of clipper should I purchase that will accomplish my task and not scare my dogs with the high pitch noise?  What do you use?

Answer
Norma,
the trick is not to get matted isn't it?
So in case it does the best blade to use - but you must be careful- is a #7 skip tooth, regardless of the clipper.
Of course it should be a professional model- Wahl, Andis, Oster are a few I use.
The skip tooth gets under the matts but can knick the skin if you are not experienced-
maybe you need to take them to a professional a couple of times a year to avoid any accidents. Keep them on the short side.
Then try keeping them brushed and COMBED (the biggest secret!) out- there are great tools out there but you have to use them regularly.
Also put them on a secure grooming table- that way the footing is sure and they know their boundaries. None of this wrestling on the kitchen table or the floor. Very dangerous.
good luck.