Imagine hearing a flute, but not seeing the player. Then imagine hearing a voice, perhaps a song, but not seeing the person or being able to work out any words of the song if there are any. Compare the amount of information one can glean from these two situations. The voice would probably give us some information about the performer: age (child or adult), gender assigned at birth (male or female) and possibly even health, because the voice innately contains personal information the listeners understand. It will be hard to figure out the age of a flautist without seeing the person, and the age of the flute… well, someone will have to supply us with that information.
Next, imagine hearing a scream, cry or laughter. A scream usually signifies an intense emotion. If it is in the middle of the night, perhaps the person is in danger. If the scream is followed by laughter, perhaps it was a joyous occasion, or someone played a joke. Whatever the case, these wordless vocals, or nonverbal messages, will elicit some sort of response in the listener because they carry meaning the listener would understand. It is a sort of a biological code. The voice can express that which cannot be expressed in words.
Instrumentalists are often interested in the vocalist’s ability to sing words, the bringing-to-life of written texts within the musical sphere. But the voice already carries so much information, and add to this the inputs from lyricists and composers… and the listener is bombarded. That moment when the vocalist holds one powerful note and the crowd goes wild? Someone once told me that the emotion resides in the vowels. Perhaps when nonverbal message is strongly projected within a musical context, we also vibrate in ways we cannot explain. There is much room to explore in the realm of wordless vocals in the context of musical compositions, which we can start by using very simple tools such as long tones, crescendos and decrescendos, and emotional content which is rarely discussed except in relation to words.