[The lombard reflex as a test of vocal function (author's transl)].

Any impairment of audio-phonatory control by background noise is followed by an increase in both the intensity and pitch of the speaking voice (Lombard reflex, 1911), thus increasing vocal strain. As a consequence, it might be anticipated that persons reacting to noise with marked changes in voice might be more liable to develop dysphonia. 22 singers, 34 normal controls, and 22 patients with hyperfunctional dysphonia where studied. In all patients, both ears were gradually masked with white noise. The change of the mean intensity level and of the mean pitch level of the speaking voice were then measured objectively with a special fundamental frequency analyzer (Fedders and Schultz-Coulon, 1975). Results show that the increase of intensity is comparable in all subjects, whereas the elevation of the mean pitch level differs significantly: trained voices (singers) react with the least pitch increment whereas dysphonic patients react with the most. The following conclusions were made from the present investigation: 1. Extreme increments in pitch level can be considered to be a more significant etiological factor of dysphonia than intensity increments; 2. Vocal therapy and voice training may have a favorable effect on the Lombard reflex (probably by improvement of the kinesthetic control mechanism) so that the speaking voice in a noisy environment is raised less with less vocal strain. The study also indicates that measurement of pitch changes during binaural masking can provide important information for the diagnosis, therapy and prophylaxis of dysphonia.