Have you ever wondered why, sometimes, when you’re playing one of your pieces, you hear an extra ringing sound? Kind of like a faint, magical echo that matches the note you were playing?
Welcome to the magical world of sympathetic resonance! Sympathetic what now? I always get overly excited when I see a perplexed expression on one of my students’ faces, knowing they heard the barely noticeable faint ringing sound. I then cascade into a passionate discussion on exactly why that sound occurred, crediting “sympathetic resonance”, at which point they look even more perplexed than when they first heard the sound.
What is sympathetic resonance?
Though the name sounds complicated, the scientific principles behind this occurrence are actually quite understandable. And luckily, the word sympathetic can actually be useful in understanding the strange phenomenon. Sympathy is something we are all quite familiar with. When someone feels something and, as a direct consequence, we feel it too, we call that sympathy. In essence, it’s when the emotional state of one person causes the same emotional state in the other. Likewise, notes can have a certain sympathy for each other, as we’ll see below.
Every note has a different pitch, which is really just the frequency of the note’s vibration (if you want to learn more about this, check out this article!). For instance, let’s take one note – A 440 Hertz. 440 Hertz (Hz) simply means that the note vibrates exactly 440 times per second (yes, that is a LOT!).
Now, let’s take an object that is commonly used for tuning instruments: a tuning fork.
Once you’ve sounded a tuning fork, if another tuning fork is a few inches away and is tuned to the same frequency, it will also start to vibrate. Essentially, the vibrations from the first tuning fork vibrate the air around it, which means the air around the second tuning fork, if it is close enough, is also vibrating at that frequency. Since this is a familiar frequency to the second tuning fork, the vibrations of the air around it cause it to start vibrating “sympathetically”. It’s almost like it can’t help but sing along!
This is the classic example most physics books will use to demonstrate the phenomenon of sympathetic resonance. However, the application of this scientific principle reaches much further than we would initially think!
A quick sidenote about overtones…
This next part is going to build a bit on the knowledge of the harmonic series and overtones, so if you haven’t read about that before, feel free to check out my article about those!
For our purposes here, the main thing you’ll want to understand about overtones is simply this: that when any note is played, the note you hear most audibly is not the only note present. Every note also has overtones present with it. They are much quieter than the main note you hear, but if you really pay attention, you can learn to hear the overtones too!
Overtones follow a very geometric/mathematical pattern. Let’s take the frequency of 220 Hz, for example. If we simply double that frequency to 440 Hz, then we have found the first overtone of this base frequency of 220 Hz. What is really cool is that both of these notes are the note A! When A 220 Hz is played, the note A 440 Hz is also being played, just a lot softer. We’ll see that these two notes have a very cool relationship on the violin!
Sympathetic resonance on the violin
On violin, the note A 220 Hz is the first finger on the G string and A 440 Hz is the open A string. Because A 220 Hz also contains A 440 Hz within it as an overtone, the A string, which has its natural frequency of A 440 Hz, recognizes this overtone, and will begin to vibrate along with it. The crazy thing is, as you’re playing the first finger on the G string and you simultaneously see the open A vibrating sympathetically, the D string sits quietly in between the two vibrating strings, completely still! Complete proof of the “magic” of sympathetic resonance!
But don’t forget to play in tune!
Of course, because this “magic” depends completely on the accuracy of frequencies, it is necessary that, to do this successfully, (1) your violin needs to be in tune, and (2) your first finger on G string needs to be perfectly in tune. You will know you are in tune if the A string starts to vibrate. (Hint: the faster you move your bow when playing the note, the more visibly your open A will vibrate!)
The violin’s many resonance points
While I always use this specific example as the clearest demonstration of sympathetic resonance, there are actually many other notes which will bring out this amazing effect. As we have seen, notes which share the same letter name always have this relationship. Moreover, any note which is an overtone of an open string will cause that string to vibrate sympathetically. Some will have a louder effect than others – it really depends on how strong the overtone is for the particular open string. In fact, some notes will cause two open strings to vibrate sympathetically, because our strings share overtones with each other! For example, third finger D on A string causes both the G and D strings to vibrate sympathetically, because it is the second overtone of the open G and the first overtone of the open D.
Resonance point chart
Here is a visual demonstration of all of the sympathetic resonance points on the violin in first position. While there are others in higher positions, most of them are either repeats of these pitches on different strings or an octave higher than these notes (such as a high G on the E string – 4th finger in sixth position).
Click here for a PDF download of a printer-friendlier version.
Note that there are powerful sympathetic resonance points on the 4th finger spots of the lowest three strings, as well as on the 3rd finger spots of the highest three strings. See if you can figure out why! And always remember, an open string cannot ring if your finger is touching it! This is especially something to watch out for when we’re playing fourth finger, because we want the string above the one we’re playing to be unobstructed and free to vibrate. It can be difficult to place the fourth finger without also touching the adjacent string but, with enough practice, this can become easier to do! (A good arm and wrist position is key for this! Find out more here about how to position your left arm to best access these wonderful overtones.)
Some key takeaways
All of this is pretty amazing, right? I sure think so!
And beyond simply just being cool, sympathetic resonance is actually important to our violin playing as well. When we play a note perfectly in tune, such as the G on the D string (3rd finger), and hear the G string vibrating along, it produces an extra ringing sound that makes our tone much fuller and more resonant. When we learn to accurately play in tune and activate these sympathetic overtones, it really boosts our overall sound and tone! This is one of the qualities that differentiates the tone of an accomplished violinist from that of an amateur.
So from now on, whenever you’re playing your violin, make sure you pay extra attention to those delicate, soft overtones! They are a confirmation that we are playing nicely in tune, and they give us a powerful sound boost!
There is so much more to learn about the amazing science that goes into music, particularly violin playing! Here are a few more articles if you want to learn more: