Introduction:
It is estimated that the prevalence of hearing loss in children with Down syndrome (DS) ranges from 38% to 82%. However, the diagnosis of hearing loss in DS is difficult, due to an impaired ability to cooperate for subjective tests. Thus, objective tests such as impedance audiometry, otoacoustic emissions, and auditory brainstem responses (ABRs) may be more appropriate. In this study objective methods without anesthesia were used to determine the amount, type, and prevalence of hearing loss in people with DS.

Material and methods:
The study included 39 subjects with DS, ranging in age from 1 year to 27 years. Hearing tests in DS subjects were performed during physiological sleep or while awake. Otoscopic examination was performed in all DS subjects. If no abnormalities were seen, tympanometry, otoacoustic emissions, and recording of ABRs were attempted.

Results:
Objective hearing tests showed that the DS group had various types of hearing disorders. Based on all objective tests carried out in all ears (n = 78), the following diagnoses were made: normal hearing, 36 ears (46%); cochlear hearing loss, 27 ears (35%); conductive hearing loss, 8 ears (10%); suspected deafness, 7 ears (9%). Based on wave V thresholds, the following degrees of hearing loss were established: normal hearing, 36 ears (46%); 21–40 dB nHL, 21 ears (27%); 50–60 dB nHL, 8 ears (10%); 70–80 dB nHL, 6 ears (8%); > 80 dB nHL, 7 ears (9%).

Conclusions:
In previous studies of DS subjects by other authors, conductive hearing loss predominated, followed by sensorineural hearing loss. In the present study, more sensorineural than conductive hearing loss was diagnosed. In most cases, the diagnosis of the type of hearing disorder was based on the ABR result, and other tests such as tympanometry and otoacoustic emissions played a supporting role. Due to the often limited cooperation of the patient, the DPOAE test was difficult to perform.