Lip trill

Phonation into a Straw as a Voice Building Exercise (Article)
The value of phonating into a small-diameter straw is explained, a healthy action for the tissues while the abdominal muscles get a good workout. (posted 2:34 PM, August 27, 2014)

One More Small Step in Solving the Mystery of the Benefits of Semioccluded Vocal Tract Exercises (Article)
In addition to aerodynamic considerations, Titze observes, a vocal tract air column that vibrates (up and down) above the vocal folds can create a reactive push and pull on the tissue surfaces so that vocal fold vibration is reinforced a vocal tract that is narrow (semioccluded) in some region along its length (e.g., at the lips or the epiglottis) helps to produce this favorable push-pull. (posted 2:34 PM, August 27, 2014)

Vocalizing Vocalises (Article)
Pomfret considers perhaps the most overlooked portion of the voice lesson: the vocalise. Her methodic approach to vocalizing includes considerations of what it means to warm up, what exercises help to accomplish the task, exercises for voice building, and vocalises for special repertoire or voice types. (posted 2:34 PM, August 27, 2014)

The Five Best Vocal Warm-Up Exercises (Article)
The exercises given are those that have strong physiologic justification and are prevalent in the majority of studios. (posted 2:34 PM, August 27, 2014)