Since there is no way you can directly control the muscles of the voice, voice teachers tend to use images a lot, and fortunately it seems to work.

I find that one image that works well for me when singing high notes is not to think of the note as "high" and that I have to "reach" for it. I think of my voice as if it were a trombone. With a trombone, to play low notes, you push the slide out. To play high notes, you pull the slide toward you. When I sing a high note, I open my mouth, tighten my abdominal muscles (not my throat!) and draw the note toward me. It works much better for me than thinking I have to reach up for the note. Incidentally, this does not need to contradict the feeling that you are bouncing your voice off the far wall of the auditorium. The tightening of the abdominal muscles is the key. That and keeping the throat open and relaxed. Any feeling of strain in your vocal apparatus is nature's way of telling you to back off.

Incidentally, all this imaging takes place in practice. If you practice it well, when you are performing, you don't need to play with these kinds of images (unless you get into trouble). You think of the song and just do it.

Don Firth