Blog 12: Guitar Physics

Many types of waves surround us constantly: light waves, water waves, radio waves, etc. Perhaps the most enjoyable waves of all, however, are sound waves. Of course, these pleasant sound waves must come from somewhere. 

Enter the Epiphone Masterbilt AE-500ME.

When playing my sound-wave-generator, I did not know any of its properties as they related to physics. Now that I finally do understand all of my guitar's secrets, I can go on and on about them. 

Wave frequency in strings: When I play an open string, I create a standing wave in the string with a frequency that is dependent on the tension of the string and its length (f = √ F / (m /

L) ).  The reason each string sounds different is because each has a different mass - the low E has the highest mass, thus increasing the value of (m / L), thus reducing the frequency. 

Whenever I play a note by pressing on one of the frets, I am reducing the length of the standing wave, thus reducing the value of (m / L), thus increasing the frequency. Increasing the frequency, of course, increases the note's pitch, resulting in a higher note.

Harmonics: If I press my finger lightly to the 12th fret of my guitar on any string, I produce a harmonic that is one octave higher than the fundamental frequency (open note) of the string. However, the 12th fret isn't the only place where I can produce a harmonic; the 5th, 7th, and 19th frets also create harmonics. In fact, the 5th fret will produce a harmonic that is two octaves up from that of the fundamental frequency. 

Beat Frequency: 

As heard in the video, an irregular wave is produced when I slowly bend the string so that its frequency differs slightly from the other. This is called a beat frequency, and although I did not know why it was produced, I used it to gauge my tuning since I began playing. This method is not the best, however, because the human ear cannot discern between minute differences in frequency (as an electronic tuner can). 

Now that I know the physics behind my guitar, I will always be amazed at how a few strings of metal stretched over a piece of wood can be an endless source of knowledge, fascination, and enjoyment. However...

... I am not sure that physics has improved my guitar playing. When shall science make me a master shredder? Only time will tell.