I was watching a terrific video of Elisabeth Schwarzkopf last night, on the Medici Arts label. The recordings were taken from BBC broadcasts of 1961 and 1970, along with some footage of an ORTF concert from Paris in 1967. Schwarzkopf's artistry was stunning, of course; but I was much struck by a change in her vocal approach between 1961 and 1967.
The '61 recordings are vocally impeccable. There was a beautiful balance and clarity to the sound. Her face looked natural when she sang, all the vowels were clear and balanced, and the breath technique was good, not obtrusive in anyway, just grounded in the middle of the body. By 1967, however, this great artist was noticeably pulling down her upper lip on all the vowels, and her breath was shallow, with obvious forcing from the supporting muscles of the neck, especially on the left side.
I had long ago noticed some strange vowels in some of my favourite Schwarzkopf recordings (the Mozart and Strauss with Szell, for instance). Here was the explanation: her "ah" vowel, for instance, became excessively dark after she began to sing by pulling down the upper lip.
Don't get me wrong: that "lip thing" has been used by many great singers, including Sutherland and the great German lyric, Gundula Janowitz. I saw Janowitz sing Arabella from the side of the stage in Berlin in 1982, and I could see the lip thing at work. By that time, all of her high notes were flat, and she retired from the stage shortly after. When used with great discretion, covering the upper teeth with the lip can settle the vocal position by lowering the larynx; but if you overdo it, it leads to vocal trouble.
Best of all, is the goal of singing with no gimmicks; just good breathing, good support, a released jaw and larynx, and a healthy frontal feeling of placement. Beware the quick fix!