The same pressure can be associated to strain or perfect phonation. There are many ways to produce the same pressure: creating it before the attack, on the attack, with a certain speed, at a precise speed and with or without suspension, with some muscles and timing and reciprocal order of movement, putting a tension in some part and then just creating a slight tension in another part to create conditions for the attack etc. Understanding this is fundamental to have a correct attack and many different ways of attacks accorded to musical and interpretative requirements.
It is called fiato (breath) a certain precise movement of connection bewteen a pressure under the glottis and the voice, being that not a flow of air despite the name. It is a force, a pressure in the muscles, a lightness in the throat, a point of concentration, a posture given by a precise muscular movement.
Often it is said that the larynx has to be low; and in my experience this is often a misunderstood concept. In the high notes it has to be high enough to be correct for their production. There is a range of movement that is correct for voices and notes production and it is in this range that we have to manage its movement. Tha larynx has to be in that range for every note, just lowering in the moment of voice production. To have in all the extension an innatural low larynx will create more problems then it solves, and will need an exaggerate need of pressure that can be accepted and desired only for the last notes of each tessitura or in certain cases of belting. The larynx will come up and down in a controlled way along the tessitura, just it will lower a bit in the correct attack.
One of the fundamental points in technique is when and with what position making the first turn, also called copertura. Great part of national schools and national taste in sound is given by this position and way of making the copertura. If you prefer you can think about it as the first point in which you make the turn of the larynx, being the second the necessary one to obtain the high notes in female voices, falsetto in men and a certain kind of successive slightly turn for high notes in men voices that don’t desire a falsetto sound.
It gives the clear and precise english sound in medium and medium high register with its quite high position and the habit of not getting below, the somewhat flatted and falsetto sound in France, the velvet and lightness of accent and high tones in the spanish due to the involvement of soft palato to obtain the copertura, the always connected to sustain of american school that gives more strenght to the nearly same position then english school but less poetry in the ovetornes, the low position in german school that need to put some intubation to make the turn possible and connected, the perfect balance of all these elements in italian belcanto school, the slightly below positions of the swedish italian belcanto that gives more weight by the lower positin, the russian school which now is the closest to the italian belcanto we have.
The first turning oint can be moved and managed both by pronounciation or use of mask muscles and soft palate or nose inside muscles and the sustain and appoggio muscles and the posture in itself. It is something to think about when starting a training and also it is to have a strategy about according to repertoire and market in which the singer is working.
There is only a way of being appoggiati and sostenuti, and it depends on a certain precise connection between diaphragm and larynx. You can hear it in a certain kind of overtones for the sustain and a related way for the appoggio, being that relation perfect when you can correctly execute a messa di voce (from pianissimo to forte or fortissimo and back to pianissimo). The way you perceive them and where you feel in the body depends on style, vocal range, individual body and body specifities, technical level (the higher level pass from a point of similarities of perceptions). All the places everybody can feel must work during the correct vocal gesture, so often in the training we have to work what you will never feel while singing, because it is the balance of all the places of diaphragm insertions with some wanted overacting that make the correct appoggio and sustain for style and voice.
On this subject one of the more common mistakes is to overwork the insertion you want to be heard in the sound, without noticing that it is the lack of some others that make its work not satisfing, the second being the fear for the overdoing of some specifics and the choice to make every voice simply and prudently just balanced without any specifics (losing in that way what of personal and truly specific a voice can produce in a deeper level).
For a singer or a performer it is often more effective looking for vocal solutions thinking in a way that has a vocal logic instead of a truer one. We have a point of acting to obtain the voice so deformed by instrument way of being built and related and cohordinated and the fact that we are inside that we have to accept and make allied this deformation. The vocal correct gesture acts in all its possibilities only from a vocal way of perceiving and thinking; if we know that well we don’t need to make confusion bewteen what and how we think to sing and how we really act to sing.