for those on the fence about hearing protection..

[Richard Brekne]

Well... to each their own as it were... and whatever works for you.  I 
would like to point out that pounding hard is pure and simply not 
needed.  With a good hammer technique one can feel all one needs to in 
order to <<know>> exactly whether the string is set well enough or 
not... without playing hard at all. A reasonably firm test blow one time 
can certainly be re-assuring... but if you've set the thing right to 
begin with it wont move.

Hard blows can indeed, as others have pointed out, make the tuning 
unstable forcing to much of the tension through the termination 
points... only to be selv-released later on.

If your tuning is unstable... its not because you are hitting either too 
loud or too soft.... its because you don't have a good enough tuning 
technique.... its in the wrists and hands and fingers.

Cheers
RicB

    I agree with you completly Phil, there is no such thing as "pounding
    too hard" unless you are breaking keys regularly! I frequently
    follow the light touch techs and tooners in this area and find the
    piano settling more under my touch/pounding but when I finish my
    tunings stay put! I have had the comment more than once that I was
    the loudest tech they've ever had, which I take as a complement, I
    then explain to them why. Oh and yes I use hearing protection also!

    Mike