One of the most popular vocal exercises today is the lip trill. What is a lip trill? Why is this funny sounding trick so in?
Here´s how you do it: blow air gently through your pursed lips letting out a sound on any given pitch. It sounds like children´s play or like a kazoo. You can do any scales, intervals or melody patterns or even whole songs on the lip trill.
So what´s the benefit of this? One of the world´s most prominent voice scientists, Prof. Ingo Titze, is a great proponent of an exercise called singing through a straw (see his video). It is equally funny, to tell the truth. Yet singing through a straw, doing the lip trill, doing the ng-sound (the siren) – all these exercises have something in common. Elegantly speaking, they are called singing through a semi-occluded vocal tract. In other words, you sing while making a partial stop or hindrance in the vocal tract. This has the effect of changing the conditions of the resonance cavities through which the sound travels. Interestingly, it also affects the vibratory pattern of the vocal folds themselves, causing a back pressure that enables the vocal folds to vibrate more easily. It enhances the vibration of the thin edges of the vocal cords. That is very beneficial for the cords, especially when warming up the voice or if your voice is tired.
So that´s why all those funny sounding little exercises are useful! The lip trill calls for an even flow of air, very soft and relaxed lips, thin vocal folds and control of air pressure. This air pressure must be constant but absolutely not too high. That´ s why the singer has to do it right if he wants to execute it at all. Otherwise it almost won´t work – I would say, done correctly the exercise literally teaches itself! The vocal folds thin out and the register breaks seem to disappear. You can easily vocalize your whole range with the lip trill, as well as sing through a straw.
If you can´t get your lips to buzz, lift them slightly with your fingers. Feel the sound very forward and relax your jaw. You can think of the vowel U inside your mouth, that way you may keep your larynx relaxed. Engage the whole body and imagine the sound moving all around you for best balance.