Webster defines the word blend as "mix; especially : to combine or associate so that the separate constituents or the line of demarcation cannot be distinguished". So in the vocal and a cappella world this would mean to unify the group's sound. (I agree with this so far.) Unfortunately, there is often not enough discussion on what makes up a group's sound or how to achieve a "good blend". It is usually assumed that your singers will automatically understand what you mean. Well, this is where I hate "blend".
For some reason, many singers and directors believe that blend is achieved by everyone sounding the same and that Susie now has to give up her own personal tone and voice to sound just like Sally. Ummm wrong. Your body, for the most part, knows what's up and knows the only way for you to be singing healthy. So whatever Susie is doing to sound like Sally is probably wrecking her voice and ultimately sacrificing how long she will be able to sing.
DISCLAIMER: I will always preach that the vocal, physical, and mental health of your singers is number one! If your singers are sick, then they can't sing, and you will have no group. So always promote healthy singing! ALWAYS! I will harp on this many, many, many times! Allow for an open environment in which your singers feel like they can say whether or not they can't do something or if it hurts, never FORCE them to sing something they don't feel comfortable with. As I said, your body knows best.
Plus, you let Susie into your group because of how she sings, not for her ability to sing like someone else or the rest of the group. Her tone and vocal quality obviously have something to offer your group, something you liked, and something you thought would be a good fit. Let's be honest, why would allow someone into your group because you don't like how they can sing but think you can change them to fit better? That seems...well...counterproductive. So rather than falling victim to the "Blend Monster" of unhealthy singing, why not break it down into concepts your singers (and yourself, as a singer) can grasp easier?
I like to break it down into three main concepts: voice matching, vowel unification, and tuning. While all three make up what should be understood as blend, they are far easier to understand when isolated. Here is how:
This may seem like the most abstract concept of the three, however when mastered, voice matching will help lead to ease in vowel unification and tuning. Therefore, I like to address it first.
It's actually pretty simple, some voices sound good together and some voices don't. I'm not talking about an entire group of people, I am saying literally two voices. Whether it's physical proximity or singing the same part, certain voices due to color, clarity, speed of vibrato, etc. just complement each other or some seem to naturally fight each other giving the illusion of being out of tune. So what you need to do is identify the groups of voices that just work together. Sometimes if two voices seem to fight each other, adding a third voice that seems to "bridge" the two is all you need.
How do you put this in practice? I often like to have the group sing in a circle around me on an "oo". First I have them sing tonic (or scale degree 1) and shuffle voices around (literally tell people to move their bodies to where their voice is a better match) as I see fit. Then I identify the group of singers that will be singing the top part of a four part harmony, and have them sing tonic up the octave. After some more shuffling and once tonic is locked in, I choose singers to add the fifth of the chord and then the third. At this point, I can ask a singer to switch notes, where their singing, play with dynamic contrast to establish a sound, etc. and then use different vowels and make minor adjustments. I suggest "ah" or "oh" to contrast the sound of the closed vowel you just used. This is a 10-20 minute exercise that will save you oodles of time down the road.
Once you've set vocal matches, you can now grasp an idea of with whom, what part, and where each of your singers should be singing for each piece.
While I am of the school that enjoys taller and more classical vowels (mostly due to my classical voice upbringing), it doesn't really matter what vowels you use, as long as you decide on something. I do think that the taller and more pure vowels are easier to unify, especially in large groups, however they may not play well into your group's style or sound.
I have found the best way to unify vowels are through unison exercises. Demonstrate the vowel you would like, ask your group to observe the color and shape of what you are singing and have them try to replicate what you are doing without trying to sound exactly like you. Then use words like rounder, darker, brighter, taller, thinner, etc. to describe how they should think about the sound you are trying to achieve. Often i have found that words associated to something tangible work best.
Now, I have seen and heard some pretty incorrect ways to achieve different sounds and vowel colors. One example is to tell your singers to put more air or breath in their tone. While this technique seems to work towards an immediate unification of sound, it is horrible for vocal health (told ya' I was going to harp on this a lot!) and in fact, makes unifying sound more difficult because it robs the voice of its full overtones. Furthermore, adding air or "more breath" to one's tone fosters poor breath support habits, as well as leads to the swelling of the vocal folds from their inability to come together and can result in many vocal problems including the formation of vocal nodes. Basically, DON'T DO THIS!!!!!!!
Also, pay attention to how your singers are creating the color you are asking of them. Often, when a taller or darker color is asked for, untrained singers tend to focus their tone towards the back of their head and their throat which results in tongue tension , or the tensing of the root of the tongue. It is pretty easily identifiable when your singers tongue seems like it is in one big wad in the back of their throat. This habit will usually result in pushing the sound and many other poor techniques.
Try to be wise in how you ask for the vowel shape and color you are asking for. Again, sacrificing one's natural tone for the sake of "blend" is NOT what you want.
To be quite honest, once you have the first two concepts, you will find that you are faced with far fewer tuning issues. However, that is not an excuse for a lazy ear. Find exercises that challenge your singers to actually listen to the rest of the group instead of just themselves. Seventh chords, add 9 chords, and add 6 chords are great for this because of their built in dissonances but also because of the impact they have on your singers once tuned. They will be floored at the sounds and overtones they are able to make. I also suggest the exercise discussed in voice matching. You can't place the fifth of the chord until tonic is completely in tune and then you can't place the third of the chord until that is in tune. Just constantly find ways to have them use their ears and become aware of tuning issues themselves. (I will be discussing other tuning exercises at a later time.)
Wrapping it up, I think exploring "blend" in the three isolated concepts will make it infinitely easier to create a consistent and unified sound. I still think using the word "blend" can be dangerous simply because of its connotation to sacrifice a singers individual tone and suggest that you use it with caution. Basically, beware of the "Blend Monster"!
Until the journey continues....
p.s. Don't forget to leave me your comments or send your questions and suggestions to firstname.lastname@example.org!