On teaching yourself to distiguish (harmonics) overtones

Harmonics is an unfortunate term as almost nothing in nature is exact multiples of integer numbers.


The correct term is overtones.


Exact overtones of x2, x3, x4 in frequency may be heard by listening to 80s video game sound content.


Real good acoustic instruments and synthesizers depart from the exact multiples a little. This little makes all the difference.


To repeat. Real good instruments have an overtone producing structure slightly expanded in frequency and thus makes a tremendous difference to our brain perception.


For example, for correct octaves to our brain, the higher frequency must be a little more than double. For example if  an A of 440Hz has been played then 880Hz sounds a dramatically bad octave.  It may be for example that 882Hz sounds correct.


It also depends on intensity, ie how must acoustic energy is put out by the source of sound. Higher intensities give a flatter impression to our brain, ie lower pitch.


How can I prove all these to myself?


It is very easy, you can use any online signal generator, input the numbers and let your brain hear and decide.


And now to the topic.


The teacher for distiguishing overtones is the acoustic piano itself.


We play for example middle C, C4. We keep pressing the key even after the sound has completely decayed.


While still holding we play C5 ie one octave above for say 1 second only.


Although the higher note is released we keep hearing it on a well tuned piano.


What we hear in fact is the second overtone (mode of vibration) of the lower sting still held undamped. We can easily prove this be releasing now the middle C key and witness the C one octave above sound to stop!


We can repeat this experiment keeping again C4 held and then playing G5. This is the third overtone.


Then C6.


Then E6.


Then G6.


Then C7 etc.


The interesting fact is that now that we can hear the overtones of C4 individually, it becomes much more easy to distiguish them when the C4 note is being played alone.


All these notes on the overtone (harmonic) series of a correctly stretched sting at high tension is the basis of C D E F G A B , Do re mi fa sol la si or the C major scale from where most of our music springs.


References:


Discussions with piano tuner Albert Ketenzian


Musical Acoustics - Donald Hall


Waves - Berkley Physics Course


Lectures of Leonard Benstein on Youtube


Other euroelectron posts


Piano, Servicing Tuning and Rebuilding - Reblitz

Online sinewave or tone generator

Our ears, our brain


Sound and Hearing - Time Life Encyclopedia - Stevens


Hearing - Stevens and Davis


Octave Stretch - Ernst Terhardt - Euroelectron