September 15, 2006
Those Leaky Kalimba Notes

To understand the kalimba's wah-wah effect, we need to first understand what the kalimba does when we try to play a single note. Actually, the vibrations travel from the tine you played, along the bridge, and to the adjacent tines.

Here is the spectrum (after the attack) of the low G note on my Alto kalimba when I hold my fingers on all the tines except for the low G and I pluck that tine:

The big peak is at the frequency of the low G, and that double peak to the right is F# and G an octave higher, which are somehow also ringing (in the kalimba box? on the low G tine? I don't know).

Now, if I just play the low G the way I usually do, without preventing the other notes from ringing, this is the spectrum I get:

For starters, the G is louder (higher peak). You can still see the F# and the G in their double peak, and they are louder. And in between you can see the A (at the foot of the low G), B and C blended together (they are a half step apart), D, E, F# and G. Then continuing up, the A, B, C, D, E, tiny F# (it is a bit dead on my old kalimba), and the highest G. Above that, the other notes are overtones, which we won't go into. So, when you play the low G, which is centrally located in the middle of the kalimba, you get a bit of every single note on the kalimba.

Now, I'll show you the post-attack spectrum of the middle A (ie, the colored tine in the middle of the right side) when I damp all other notes:

There is a bit of low lying stuff at various frequencies, but the spectrum is totally dominated by the A note.

Now, if I play the A naturally, letting other notes ring, this is our spectrum:

The big peak is A. Just below A is G, on the opposite side of the kalimba, a tiny peak. Below that is F#, a big peak, and right next to A on the right side of the kalimba. Looking at higher frequencies, there is only a bit of B (on the opposite side of A on the kalimba), and there is a lot of C (right next to A on the kalimba). There is almost no D (opposite), and there is a fair amount of E (same side). And there is a lot of the high G, and then an A overtone.

So, the extra notes we get ringing are mainly the notes which are adjacent to the note we played. But we get a bit of all the notes on the kalimba.

And how does this relate to the "wah-wah" effect? You'll just have to come back for more next Friday. And the Friday after that.