I recently discovered by accident that my favourite coffee cup can produce two different frequencies, and a chord containing both.
I test-played it (explanations in German, maybe automatic subtitles work) here:
The most important observations from these experiments are:
- My cup produces the frequencies F6 and Eb6.
- The handle adds mass on one side, which causes an asymmetry, and introduces two different frequencies. Near the handle, the extra mass limits the vibration, causing a higher note, F6. On the opposite side, the cup can vibrate more freely, creating the Eb6. According to ChatGPT, this means that the cup has two orthogonal modes. Without the handle, both frequencies would be the same.
- In the middle (in my case, at ~30 degrees away from the handle), you can PLAY A CHORD. The intensity of both notes varies as you move along the cup!
- Angle, vertical position and force of the nail / snipping influence the sound. For reproducible sounds, playing as horizontally as possible worked well for me.
- Open sound vs. dampening sound: To create a clear, bell-like sound, play the cup on a surface. To make the sound very short, hold the cup in your hand. To dampen the sound early when playing on a surface, simply touch the handle or rim of the cup, as in any other instrument.
- Further modification: Fill the cup with water to make it sound lighter. For lower tones, take a bigger pot such as a plant pot with a handle on one side, or add some weight on one side, try a parabolic shape with a flat bottom, as in my cup.
Why is this interesting?
The cup offers two frequencies that are not observed in natural harmonics of a guitar string, where only fifths and thirds are observed. By using ceramics, you get more and varied sound colours.
What can you do with it?
In theory, by experimenting with cup size, cup shape (different conic sections), cup wall thickness and handle mass, you can create any interval from a minor second to a major seventh. I think that the wall should not be too thick. My cup has approx. 3 mm wall thickness. (Gmundner Keramik Kaffeetasse Maxima, rainbow edition.)
You could then introduce something that makes the snipping process (and the resulting frequency / frequencies) reproducible, like a hammer as seen in a classical piano.
If you build the hammer so that it can rotate 180 degrees to and fro, you can start with one note, gradually move into the chord, first hearing the first note more loudly, reaching equilibrium, then hearing the second note more loudly, until you end in the second note.
Imagine that, for example, two cups are played simultaneously. In jazz music, two notes of any chord produce the lead tones of this chord. (2-7) Let us imagine that you are playing the lead tones of a chord of your preference. Now, you want to change to another chord. You could do this by making a simultaneous rotation of both hammers. For a while, you will have very colourful chords, until you end in the final tones, which could be another lead tones chord pair. It would be similar to a guitar slide, but in the form of a chord, and in stakkato mode. Maybe you could pre-program the board to make the slide in a specific amount of time, and hold a predefined rhythm (sort of like a step sequencer), and map this transgression on a custom button. You could use this to accompany another instrument. Since the notes are not very long, you would probably want to play them more than once, maybe as quarter notes. In open playing mode (on a surface), the maximum length of any given note is perhaps approx. half a second.
You could also play e. g. two cups simultaneously in chord mode and get e. g. a Dm7 chord with all four notes. Some mathematicians, musical theorists etc would need to think about which chords to choose, how to position the cups and operating knobs so that it intuitively makes sense to a piano player / organist / xylophone player. With 6 cups, you could, with good planning, represent all the notes on a well-tempered keyboard. You may want more than those, though, to have more octaves, and perhaps to try more colours / different intervals.
How to operate the instrument:
Such an instrument could be operated with knob potentiometers which you recognise from every standard mixing board. The two notes would be written on each knob so that
0 degrees = -infinity = frequency 1
12 o'clock = 90 degrees = chord
180 degrees = max = frequency 2
Turning the knob will make the hammer move to the indicated position.
To play the note(s), press the knob from above = the hammer hits the cup.
This would allow you to play frequency 1, move to frequency 2 and move back to frequency 1 again without having to play any position in between on the way back to frequency 1.
Further useful features:
To link any knobs of choice, so that chords will be played (up to 5, for e. g. Eb9).
A mute button for knobs that are linked, so that they can be left out occasionally, or during transgressions when the sound would get too messy.
Two kinds of dampening the sound (could be solved by introducing foot pedals):
1. making it lower and shorter by lifting the cups in the air
2. shortening the note by touching the handle or rim
What does it sound and look like?
My cup sounds similar to a bell, very clean. I imagine an instrument of this sort to be rather big, at least the size of a marimba.
As far as I could hear until now, external conditions have little influence on the pitches of the frequencies, as long as you play it at room temperature and not e. g. in an ice cave.
The disadvantage is that every cup is probably limited to its own specific frequencies, which means that any instrument would have to be pretty big. Still, I think it could be fun to play.
How to mic it:
I would imagine the operating surface with the knobs similar to a mixing board table and the cup mechanics in a box underneath. Ideally, for use on noisy stages, the cups should be acoustically isolated from the outside. A mic, probably a small membrane mic, or two as for a piano, could then be placed inside the box. For practical reasons, any touring musician would probably have two fixed small membrane mics with XLR outs pre-installed in the box.








