For decades, scientists thought a key element of generating voice was the Bernoulli effect, the same change in relative air pressure that allows airplanes to fly and curveballs to befuddle batters.
We now know, however, that voice generation is far more complex. Muscles in the vocal folds provide resistance to air in the lungs. As air is exhaled, it pushes between the folds, which open and close rapidly. Air above the folds is alternately compressed and decompressed, creating sound waves.