Lombard Effect

The Lombard effect is an involuntary tendency for a speaker to increase his or her vocal effort to enhance audibility when speaking in a loud, noisy environment. Changes include not only loudness but other effects, such as pitch, rate, and duration of syllables. The reflex is also known as the Lombard reflex. The reflex was discovered and described in 1909 by French scientist Étienne Lombard (1869-1920). It also exists in nature, i.e., among birds.