September 8, 2006
The Frequency Response of Your Kalimba

(We are leading up to explaining why the "wah-wah" effect works very well on some of the kalimba notes and not at all on others.)

Do this experiment on your own with your treble or alto kalimba. Play every note from lowest to highest. Try to play with equal initial force on every note. If you have a means of recording the sound in your computer, do so for each note, as this will give you a way to measure the amplitude of each note's vibrations; otherwise, you are just doing it "by ear".

Now write out the number of each note, starting from lowest to highest (i.e., on the alto, low G is 1, the colored A to the left is 2, the colored B to the right is 3... on up to high G which is 15), and write down how loud the note is.

If you are doing this by ear, pick a number between 1 and 10, where 10 is the loudest. If you recorded this, look at the peak amplitude in each note and write it down in dB or decibels, which is a relative measure of loudness using logarithms. Zero decibels means as loud as it can be without saturating, and -10 dB means you are 10 dB below saturation, -20 dB means you are 20 dB below saturation.

If you are a visual person, you can plot out the numbers you wrote down on an X-Y plot, where X is the note number and Y is the note's loudness. This plot is like the natural equalization curve of your kalimba, or a frequency response of the kalimba.

Now take an index card, cut it into three pieces, and tape it over the sound holes on the front and back, and repeat this experiment, noting your results. If you are doing it "by ear", you might want to go back and forth between "sound hole open" and "sound hole covered" to get a better relative measure of the loudness.

I don't really know yet how many people are reading these tips, though I am hoping they will become hugely popular in time. Shine me a light--if you do this experiment and make a graph of your results, send it to me, and I'll post your results next time when we explain what is going on here!