There is amplitude which is rated in volts, and is how much energy is put into the waveform; and then there is Hz (Hertz), also known as a cycle per second.
When we generate 10 cycles per second, we call this 10 Hz; and we can invest 14 - 20 volts of energy into the waveform which is oscillating up and down 10 times a second. How high and low the waveform oscillates is determined by the amplitude.
When we use kHz, this is short for kilohertz, or one thousand Hz. Therefore, 10 kHz is 10 thousand cycles per second. Just for fun, MHz is megahertz or one million cycles per second, and it goes on and on. Your microwave runs about 2.4 GHz or gigahertz, or 2.4 billion cycles per second.
Generally our nervous system and muscles resonate with frequencies that are 10 kHz or less. This is why the reduce amplitude threshold defaults to 10 kHz. David has tested his threshold for interaction and found it to be from 1 kHz and down.
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