Why Your Piano Is Always Out of Tune

Did you know that when your piano tuner comes to tune your piano, he or she purposefully puts it out of tune?! While this might sound odd, a look back through history will reveal the logical reason.

Before the 1500s, musicians used what is known as "Pythagorean" tuning. This refers to the famous Greek mathematician Pythagoras who was around during 6 BC. The tuning system relied on tuning the keyboard to perfect fifths, or in mathematical terms, 3:2. They would also tune using the perfect octave, or 1:1. Without getting to involved mathematically, this tuning resulted in some keys sounding fine, while others sounded hideously out of tune, especially the interval of a 3rd. Take a listen:

This video demonstrates the most out of tune interval first, also known as the "wolf" interval. It then performs Chopin's "Revolutionary" Etude in Pythagorean tuning, which to most ears, will sound relatively normal.

In this video, 7 octaves are played along with 12 perfect fifths. This sounds normal until at the end, where they play the same note together; one that has been tuned with octaves and the other with perfect fifths. You will notice a distinct out of tune sound, because the resulting tuning is mathematically imperfect! The difference in the sound of the two similar notes is known as the "syntonic comma".

After Pythagorean tuning, musicians tried a whole range of tuning systems, which put certain intervals mathematically out of tune. One of the more famous systems was the "well-tempered" system, used famously by J.S. Bach in his book The Well-Tempered Clavier. This book proved that each key could sound relatively in tune compared to Pythagorean tuning. This video is a little long and in-depth, but provides a lot of good information on the differences in tunings:

The resulting tuning of the modern day is now "equal temperament" which again purposefully puts some intervals out of tune to make every key sound relatively more in tune. Thanks to technology, many of your keyboard devices and music software come with the option to change tuning systems. Try it out and play a scale, or your favorite piece and see if you can tell the difference!