I do a lot of rehab in my practice as a teacher, as well as fix severe pitch problems. One of the things I've found over the course of my years as a technique specialist is just how so many beginners, moderate, advanced, and even professional singers do not realize the importance of using the articulators (the lips, teeth, tongue, and palate) when pronouncing the consonants/ words of songs. Few singers realize that it is the articulators that become the propelling mechanism when singing songs, rather than the air and breath support when learning how to strengthen these things in exercise with vowel sounds alone.
It can always be a stylistic choice to dig deeper, breathe in more heavily, add grit or rasp to the voice, etc. for sound and effects, but I believe these choices must be conscious ones. This may require the expertise of someone who has learned how to do this without injuring the mechanism. Preferably, a coach who specializes in this style of singing. When one of my students has a desire to learn how to scream, growl, and/or add rasp after they have a good foundation, all breaks bridged, a grasp of how to protect their instrument , preserve it, and how to correct a problem, I will make a referral. Effects like these are not in my field of expertise.
Again the articulators are located in the mouth. They are the tongue, lips, teeth, and the palate. Consonants are not supposed to be pronounced from somewhere inside the neck by grabbing these muscles for a consonant like G, or from muscles contracting in the gut for one like M. If this is how you have been going after things, then you have probably felt quite a lot of discomfort while singing, especially when trying to reach the higher notes of songs. Grabbing results in cramming the cords so tightly together that no air can pass through them. This results in the forcing, or thrusting up, all that air for sound, which causes the feeling of strain, especially when trying to reach the higher notes with strength and power.These are subconscious split second thoughts that occur in efforts to keep the air from escaping too fast or all at once.
I graduated with a degree B.S. in Speech (no puns intended here), though not pathology. Nevertheless I learned a lot about what happens to a voice when consonants /words are not pronounced with the tongue, lips, teeth, and palate alone. You can't do this by using all these other unnecessary muscles and expect things to go well.
Most of the time, after a singer has had an operation for polyps or cysts, they are often told by the surgeon that they cannot speak (or sing) for the next 6 weeks to give the cords a chance to heal. After those first 6 weeks, they are instructed to start with speech therapy. In speech therapy they are taught how to use the articulators. Once learned, the speech therapist may often be schooled enough to also teach how to practically apply the same concepts to song.
Having been a speech major, I know that learning how to use the articulators rather than the neck, stomach, and grabbing for pronunciation for those pesky consonants can make ALL the difference in the world when seeking to sing with ease and freedom. But first it takes learning the ART of breathing and subsequent diaphragmatic support before moving into the training of exactly how to use the articulators. Imagine being able to jump around on stage like a banshee because you're body has been freed up enough to do so. Additionally, never have to worry about your voice anymore.
Equally important is to remember, come to know and accept, is that the task of un-doing a bad habit to re-train for a better way can be an arduous journey. It may take a few weeks of continued practice to change a habit if the habit has been a long-standing one. But it's well worth the time and effort because of how easy it becomes to sing, even those high notes, with the strength and power you seek.