All sounds that are produced are a mix of pure tone frequencies known as harmonics. There is a fundamental tone but also overtones or a “higher” sound, which creates the “character” of the sound. You can experience this when you sing a note in the shower; somehow the sound seems to have more character/depth to it. This happens because the acoustics in the shower are different and accentuate the harmonic sound. That is why singing in a space like a church feels so magical.
Harmonics were first explained through science and mathematical ratios discovered by Pythagoras around 500 BC in Greece. This concept was later expanded by Hans Kayser in the 1920s to explain how musical harmonic ratios exist as basic law in all forms of natural science. More recently in his article “The Power of Harmonics and Chanting”, Jonathan Goldman (Sound Healing expert in USA) explained that harmonics;
“are responsible for the tone color or the timbre of different instruments and our voices. Just as you can hold a prism to white light and refract the different colors of the rainbow, it is possible to learn how to use your voice to break up these harmonics into specific sound frequencies.”