Hearing can be damaged by noise and chemicals. The latter can impact either the cochlea, or the nervous centers driving the middle-ear (stapedial) and the olivo-cochlear reflexes. The EchoScan Audio is a new process which relies on the measurements of provoked oto-emissions (sounds emitted by ear), and more particularly of acoustic distortion products, modulated by the acoustic reflex triggered by a contralateral stimulation. Dedicated to occupational physicians, the apparatus emits two sounds: f1 and f2, records 2f1-f2, measures the threshold of acoustic reflex trigger. This approach does not need an active contribution of subjects, and can be performed without a sound-proof cabin. The first results show a large sensitivity of the equipment to auditory fatigue. Complementary tool at the pure-tone audiometry, it should improve the early detection of noise and chemical effects on hearing from workers exposed to several multiple factors (noise plus chemicals).