Playing songs in different keys for a different sound

Music is a complicated business.  Sometimes it just cannot be explained from a theoretical perspective.  One of those areas that is particularly intriguing involves the perceived difference between playing in different keys.

Here are statements we have all heard in some form or another:

• Pick the key(s) for your arrangement based on how you want the song to sound.
• Some keys sound happier than others.
• The keys with sharps are brighter than the keys with flats.

Are these statements true or false?  Let me say the answer bluntly and succinctly: it is easy to prove scientifically that they are false.

Here is a brief explanation why: because of equal tempered tuning (which has been used extensively for 500 years), every note on the piano is the same distance apart.  That ensures that every scale sounds exactly the same regardless of what key you start on, which in turn assures that every key sounds exactly the same. 

Since the answer is not really debatable (at least from a theoretical viewpoint), it leads one to wonder why so many people believe otherwise.  Here are some possible reasons.

• That belief has been passed down through the generations from the time when there actually was a difference between keys (equal temperament became popular during the Fifteenth Century). 
• There is something we do not understand scientifically about music.
• We do not give our ears enough credit and people do actually recognize the keys because of the pitches themselves (rather than the relationship between pitches).  You could argue that this is scientifically possible since some people have perfect pitch.  In fact, I do not have perfect pitch, but I can almost always identify the key a song is being played in.
• There are intangibles about music we just don’t comprehend.
• We have brainwashed ourselves into believing something that just isn’t true, and our minds play tricks on us when we listen.
• It may be true on some instruments based on the instrument itself.  For example, if you play in sharp keys on a violin, you might use more open strings which leads to a different sound.

There may be other possibilities as well.  I don’t know the answer but I suspect several of these theories may explain why musicians believe that the selection of a key is important.

What do you think?