Compared to the much of the animal kingdom, human beings have pretty terrible hearing. We have poor powers of echolocation, especially for sounds that come from behind us, we can only hear a relatively narrow bandwith of 20Hz-20kHz, and weÂre easily fooled by illusions.But perhaps the most convincing tricks are the ones we play on ourselves. Expectation is one of the most powerful forces in shaping our perception, and itÂs the reason that the same wine tastes better if weÂre told it costs $90 instead of $10. The same goes for our stereo systems if you show an audiophile an anaconda sized power cord and compare it visualy to an genric cord. Which one do u believe he/she will pick out as being the best sounding? This is why blind testing works best determining if changes made are viable.