A vowel is a speech sound produced through an open vocal tract with an unrestricted airflow. There are hundreds of vowel sounds. When vowels are used there is no constriction or tightness in the vocal tract. Vowels are useful in vocal technique to help with tuning, increase airflow, decrease airflow, drive the voice towards a “headier” resonance or drive the voice towards a “chestier” resonance. Vowels also help to place the sound in the back, middle or front of the mouth.
When it comes to singing, each vowel that is sung needs to be changed slightly to a place that is unique to each individual. For example, the vowel A: You can sing it AUH or AAH. By singing it the AUH way you are not pulling the chest, widening the vowel, or causing tension in your throat.