Since the human voice will be the main subject of this blog we might as well ask ourselves: What ís the human voices, and how does it come into being ?
I think we can say that if we “use our voices” we create sound. And sound is: vibrations that travel through the air (or another medium) and are processed by the ear and perceived by the brains as a sound ‘sensation’.
How can we, humans, create these air vibrations to make “voice” ?
I will try to explain it simple. If you want to know more details, I can recommend some nice books…but maybe you don’t need too much detail to understand a little bit better what our body, our instrument, needs to do to make “voice”. Still, you may want to read the following text another two times before you get the picture… 🙂
When we want to make a sound with our voice, our brains will give orders to certain muscles to start a complicated process in our body.
The brain will give orders to muscles situated in the larynx, to close the vocal folds firmly. We call this the process of adduction of the vocal folds. At the same time, muscles that control our breath get the order to increase the air pressure in the lungs. The most important breath-muscle is the diaphragm that will start to move a little bit upwards. This reduces the volume of the lungs and as the air cannot escape (because the vocal folds are closed…), the pressure in our lungs, or more correctly: the pressure under our vocal folds known as the “sub-glottal pressure” will increase. This refers to the “glottis”, the name for the opening between the vocal folds.
At some moment the air pressure becomes so high that the vocal folds are blown open because the muscles of adduction cannot resist the air pressure anymore. When the vocal folds open, air can escape and flows through the folds.
And then, there is a law of physics (Bernouilli’s law) that says that when air is flowing, its pressure is reduced (!). As a consequence, the adduction forces in the vocal folds become stronger than the air pressure and the folds close again. As soon as they are closed, the air-pressure in the lungs (the sub-glottal pressure) builds up again and rapidly opens the vocal folds…
This process of opening and closing the vocal folds is repeated over and over again and creates a tone with some frequency, the number of times the process of opening and closing is repeated in a second. So, if we sing on a A4 we create a vibration in which the vocal folds open and close 440 times a second (440 Herz). Just imagine how fast that is !
Hmm…not an easy subject…right ?
let’s take another example of the law of Bernouilli: When you think of a train that passes in a railway station very fast…did you ever experience that you felt drawn towards that train ? It is because of the fast moving air and the reduction of its pressure that you were drawn towards the train…
The muscles that control our breath (diaphragm and intercostals) and the muscles of adduction create together the sub-glottal air-pressure we need to blow open our vocal folds. And especially the diaphragm creates this constantly maintained airflow we need for the law of Bernouilli.
If we want to come to grips with the process of creating the human voice we need to train all those muscles mentioned above to do a proper and well co-ordinated job…
This isn’t an easy subject so… if you have any questions or remarks…please send me a message !!