No evidence of hearing loss due to fetal acoustic stimulation test.
The fetal acoustic stimulation test is used increasingly for fetal assessment. To evaluate the possibility of acoustic trauma, 465 children who had been exposed to vibroacoustic stimulation in utero were screened at 4 years of age for high-frequency hearing loss. A hand-held audiometer with test tones at 25 dB for 1000 and 4000 Hz was used because responses at this level indicate hearing within normal limits for middle and high frequencies. Thirty-one children failed the test. Failure to respond was followed by inspection of the ear canal for wax, tympanometry, and reflex measurement to assess the tympanic membrane, middle ear, and eustachian tube. Hearing was retested across the full frequency range using conventional audiometric technique, and referral for otolaryngologic examination and treatment was made if necessary. The causes of hearing loss were impacted wax in 12, current or recent upper respiratory tract infection with eustachian tube dysfunction and middle ear effusion in 15, and unresolved middle ear effusion after treatment with antibiotics for otitis media in two. Profound bilateral sensorineural hearing loss of unknown origin was found in one and slight bilateral gently sloping hearing loss in another. Retesting of all children with conductive hearing loss indicated that hearing had returned to normal after treatment. None of the children showed evidence of hearing loss.