One focus of the IHTP training is learning how to recognize a “resonant tone,” or a tone that matches a sound in the environment. Ideally we match the pitch to the patient by listening to the patient’s voice, but there are times where it is useful to match another pitch in the environment, such as a noisy machine, in order to mask the sound.
Resonance is when one vibrating object acts on another object at the same frequency, as in this demonstration. We’ve all seen or heard this happen, usually with something annoying, like when something on our car vibrates at a certain road speed.
When we achieve resonance, the vibrations in the two objects play off of each other to make the sound louder. This is usually when things sound in tune, and the sound we hear is usually richer and fuller, because we have vibrations that work together, instead of fighting each other.
Resonance is NOT always good, though. Here is a video of the famous Tacoma Narrows Bridge, which succumbed to resonance just 4 months after it opened in 1944:
Fortunately, engineering has come a long way since then.
Tomorrow, more on how strings vibrate.