As a chorister, I’ve run into occasional challenges singing “in tune,” even though I’m a very experienced semi-professional choral singer, with degrees in voice and music theory. What I experience from within the choral ranks is that even when a singer is singing “in tune” in terms of absolute pitch, the particular color of a singer’s voice can make it difficult to blend, and this alone can give the impression that the person may be singing out of tune.
My soprano voice is a good example. It’s rather straight and light, and has a somewhat unusual color, sometimes more boyish than womanish, I’ve been told, especially in choral singing. (It’s good for early music and music from the Anglican tradition. I do use a richer voice, with vibrato, in solo singing, where I do not need to consider issues of blend.)
In a choral setting, it has sometimes been a challenge for me to sound “in tune” with other adult women singers, especially when there is a lot of vibrato from other singers in the soprano section. And if the prevailing vibrato tends toward the slightly under-pitch (as it often does in many choruses, see below), then my straight voice, even when I’m exactly on the center of the pitch, sounds sharp by comparison. I sometimes add some vibrato as needed to blend with heavier voices, but it’s always a challenge; of course, I’m very careful to match vowels, as this is also essential to how we perceive pitch matching. (I have trouble achieving some closed vowels, like “oo” and “ee,” when they are low in my range; I try to sing more softly in these cases so as to blend better.)
On occasion, I’ve been told by one or two choristers in my section (but never by a conductor) that I am sharp when I really don’t think I am. (About a year ago, I was so unnerved by comments (“You're singing sharp!”) that I received from an experienced fellow soprano that I asked the director privately, “Am I really singing sharp?” “No,” he said, “You’re perfectly in tune. The others are flat. Continue to sing as you were – you are helping to keep the section in tune.”) Another conductor for whom I used to sing regularly placed me in the back row of the soprano section and told me the reason why: that my good intonation would guide the other singers and help them not to sing flat!
I don’t run into these tuning challenges when I sing in choirs that use little or no vibrato, or in an all-professional choir where all the singers are adept at blending with those around them (that is, modifying their vibrato and timbre to match those around them).
My point is that our perceptions of singers’ singing “in” or “out” of tune has a lot to do with individual vocal production in the context of what the surrounding singers sound like. My gut feeling ― and I have no scientific evidence for this ― is that each of us produces a unique “voice print” with a unique pattern of overtones. The presence of vibrato confounds the overtone series, interfering with and muddying the natural harmonics. This is why it is hard to get a unified, well-tuned sound from a section where there is a variety of vibrato going on.
It seems that when singers (and their conductors) are working on intonation issues, it would be helpful to sing without vibrato, both to help to identify the center of the pitch, and to help singers understand how vibrato can distort pitch. Many singers also add vibrato in an attempt to provide a “cover” for out-of-tune singing, or to cover small errors of pitch or rhythm. And many singers who use vibrato (especially amateur singers, but a surprising number of professionals) “hang” the vibrato “on” the pitch center, so that correct intonation is achieved only when the vibrato peaks in its oscillation. This means, of course, that most of the tone is flat most of the time. That’s not a scientific explanation, of course, but it’s how I imagine it. (I’ve blogged about it here -- http://quodlibet-sarah.blogspot.com/2009/02/finding-right-voice-understanding.html).
In his warm-up routine with amateur choirs, my favorite choral conductor asks the ensemble to sing a unison pitch (in 2 octaves) on a unified vowel, senza vibrato, with crescendo. When we achieve good tuning, the overtone at the 12th pops out clear as a bell. This exercise is a terrific tool, as it provides feedback that the entire choir can hear. The more quickly and clearly the overtone emerges, the better in tune we are singing. When this exercise is attempted with vibrato, the overtone is much slower to emerge, if at all.
Food for thought.
More of my essays on the life of a chorister, and more about choral rehearsals and choral music, may be found here: http://quodlibet-sarah.blogspot.com/search/label/Chorister
NOTE: This essay is based on a reply I had posted to ChoralNet some time ago, in response to this question from another member of that forum:
[Y]ou need to listen and pay close attention to make sure that you’re in tune with the other singers. I got a couple of comments from singers in community choirs who have been singing for quite some time, but said that they didn’t know when they were in tune or not! Often their director would say that they were ‘off pitch’ or ‘out of tune’, but they didn’t really understand what this meant. Now, I have a very good ear naturally and can easily tell when I’m out, but this question has really stumped me! Firstly how do you explain in a non-technical way what it means to be ‘in tune’ (other than “singing the same note, or accurate harmony”)? And how do you help somebody experience the feeling of being in tune so that they don’t need to be told from the outside?