How can I reduce or eliminate sound coming from high speed blender (a normal, common, 10 speed Osterizer blender)
They actually make blender sound enclosures which will dampen a blender's noise considerably. These are generally designed for retail applications (i.e. expensive), but you can draw on the basic design for inspiration.
In a previous living arrangement, I actually built an MDF box/cabinet to cover and store luggable appliances along the back of the counter top. The long cabinet which opened at the front was primarily intended to avoid having to lug out the heavier appliances, but closing the cabinet doors cut the noise dramatically. You can build a blender-sized version for your purposes (or an old speaker enclosure is ideal for this application).
Put your blender on a rubber or vinyl mat to keep it from turning your counter top into a large sound diaphragm.
You can deaden the noise further by adding acoustic insulation to the cabinet; but honestly, MDF has some pretty substantial sound-deadening properties, so I don't think the additional cost (and kitchen/cleaning unfriendliness) is worth it.
I think the fundamental way of reducing your blender noise is to compare different blenders and select the one with lower noise. The noise will be mainly from the motor used by the blender, and that probably can't be reduced by you.
However if part of the noise is from the blending vibrating on a hard surface, then you might be able to reduce the noise by placing a piece (or a couple layers) of felt fabric or something soft but steady as a cushion to absorb some vibration noise.