Here’s a simple vocal experiment that one of my teachers gave me yesterday — I’ve already found it very helpful in learning to navigate my upper range.
Position your hands so they are gently cupping the back of your neck. (You’ll need to raise and bend your elbows to do this.) Make sure you can feel the spot where your neck muscles meet the base of your skull. Now sing a scale up towards the top of your range and use your hands to feel for any tension that builds up in your neck. Repeat this a few times and see if you can sing into your upper range without any buildup of tension, so that from the perspective of your hands, everything feels the same as you ascend.
This experiment has been a revelation for me — already it has given me a glimpse of what it’s like to sing high notes with feeling of effortlessness. Until trying this I was starting to doubt that I could ever hit those high notes without some internal struggle, even if I could make it sound good. (I’m a baritone, and in my case the high notes I’m reaching for are F, maybe F# or G above middle C.) As I tried the experiment I found myself making subtle adjustments to my entire posture — from head position to pelvic tilt to knee bend — all so that my neck muscles could stay relaxed. With sensory feedback from my hands, alerting me to the ongoing response of my neck muscles, all of these small adjustments in the rest of my posture came intuitively: I “just knew” what to do. I realized that until trying this experiment and actually “staying in touch” with my neck as I sang, I never had a good sense of how the neck became tense or relaxed in response to my overall posture — until, of course, the tension became extreme and I experienced it as struggle in singing. A little bit of feedback can go a long way.