Shake it up...
Sound is energetic vibrations of the air that causes our eardrums to vibrate, these vibrations transmit to tiny bones in the middle ear until they reach the inner ear where the oscillating pressures are converted into electrical signals and sent to the brain.
These vibrations move in waves called frequency (Frequency describes the number of waves or vibrations that pass a fixed place in a given amount of time) that in turn determine the pitch that creates high sounds with faster frequency, or low frequency for lower sounds (like bass).
These sound vibrations, frequencies and pitch, affect the body and have predictable affects when heard by the recipient. As an example a high frequency (fast moving vibrational wave), will cause the body to tighten, where a lower frequency will cause the body to relax.
Now since sound electrically or energetically stimulates the brain it will either cause the brain to release energy into the body in some way or cause a retracting affect. This can aid us with our Kyusho application, but only at correct times and circumstance, it is not simply the sound that works, it is when and how it is emanated during the method on a nerve or reflexive function.
Now this in turn will affect the entire body, but it is not just any sound that can be made for our use in Kyusho because as stated above different sounds will have different effects on the body or different parts of the body and or functions.
This is where many people working to incorporate this concept into their art, have difficulty or little effect, because it is not as simple as they may think. Many go to a seminar touted to be instructing Kyusho with sound and the attendee learns a mystical new approach. They then believe since they know the sound that was taught, that they have this special power. However, if they can not properly manipulate the nerve, or manipulate the nerve in a specific way to coincide with the sound, it will have little to no affect... it must accompany correct technique.
Sound is an enhancing method, it does not work without proper and high level skill in physical manipulation. And what works in the practice session when you have a dormant partner for testing, will not necessarily work as you get into dynamic action.
Different sounds are also not directional in their effect just in the wave from the source, for example a certain sound will not travel down a body compared to up, it will merely be directed in a line from the source. But it is not like a strike or pressure on a nerve, it is an internal dynamic, t does not enhance that specific strike in the nuero messaging, it affects the inner body to make it more susceptible to the attacking application. It is all in the vibratory quality in how it affects the body, not how it enhances a particular technique..
Also something to consider, if a sound is loud enough to make a person constrict their muscles, this will actually have an opposite affect for the Kyusho Practitioner when striking an opponent. This is not to say a loud sound is not useful or that sound does not enhance the affect of Kyusho on an opponent, but rather it is not the sound per say, but how and when it is applied.
Sound and it's use in Kyusho is a very complex phenomenon, it is advised that a practitioner spend more time in becoming more physically skilled than attempting more esoteric endeavors. Kyusho is not difficult, we try to make it so.