I don't hear any significant difference in sound level with my eye to the viewfinder on my K-30 in
MF and mounting the following lenses: DA 18-135 WR, KA-50, KA-50 on a macroconverter (equivalent to mounting an M-series lens), DA L 55-300 and F35-70.
Next, using the 18-135 and 35-70 at 45 degrees, from the lens in front of the camera, again in MF the sound level isn't any different either.
I do know that in
AF mode, my 18-135 is much quieter with its SDM drive versus the screw drive on my other two AF lenses. But that has nothing to do with the K-30's mirror & shutter noise.
Now I supposed somebody wants my images with the EXIF information to verify all that!