For all waves other than light waves, the motion of the observer does not change the wavelength; accordingly, the speed of the waves (relative to the observer) varies with the speed of the observer:
http://faculty.washington.edu/wilkes/116/slides/Physics116_L08-interference.pdf "Sound waves have speed c, and f and L are related by c=Lf. For an observer moving relative to medium with speed u, apparent propagation speed c' will be different: c'=c±u. Wavelength cannot change - it's a constant length in the medium, and same length in moving coordinate system (motion does not change lengths). Observed frequency has to change, to match apparent speed and fixed wavelength: f'=c'/L."
For light waves, the motion of the observer does change the wavelength so that the speed of the waves (relative to the observer) does not vary with the speed of the observer, Divine Einstein, yes we all believe in relativity, relativity, relativity:
http://www.pitt.edu/~jdnorton/teaching/HPS_0410/chapters/big_bang_observed/index.html John Norton: "Here's a light wave and an observer. If the observer were to hurry towards the source of the light, the observer would now pass wavecrests more frequently than the resting observer. That would mean that moving observer would find the frequency of the light to have increased (AND CORRESPONDINGLY FOR THE WAVELENGTH - THE DISTANCE BETWEEN CRESTS - TO HAVE DECREASED)."
http://ebooks.adelaide.edu.au/o/orwell/george/o79n/chapter2.9.html "Doublethink means the power of holding two contradictory beliefs in one's mind simultaneously, and accepting both of them. (...) It need hardly be said that the subtlest practitioners of doublethink are those who invented doublethink and know that it is a vast system of mental cheating. In our society, those who have the best knowledge of what is happening are also those who are furthest from seeing the world as it is. In general, the greater the understanding, the greater the delusion ; the more intelligent, the less sane."