Demographic study of hearing status of first grade elementary public school children in a Mexican school district.

Although the need for intact hearing to develop communication, and for early detection of hearing loss to minimize its adverse effects, is well documented and is addressed by school screening programs in the United States, in Mexico hearing screening programs are practically nonexistent and the prevalence of hearing loss among schoolage children is unknown. This study was primarily conducted to determine the prevalence of middle ear pathology and to assess the hearing status of 590 first grade public school children in school zone 34 in Queretaro, Mexico. A secondary purpose was to develop a hearing conservation model for public school-age children in Mexico. The children screened included 298 females and 292 males of middle low, and low socioeconomic status, with an average age of 6.5 years (range 5 - 12). ASHA's 1985/1990 guidelines for hearing screening were followed to implement the screening process that included visual inspection, acoustic immittance measures and identification audiometry. A Type A tympanogram with measures within a +50 and -200 daPa range for middle ear pressure, 0.4 to 1.4 ml range for static admittance, 0.4 to 1.5 ml range for equivalent ear canal volume and acoustic reflex present was considered normal for immittance screening. The cutoff criterion for responses to pure-tone stimuli at 1,000, 2,000 and 4,000 Hz was set at 20 dB HL. Results indicate that on visual inspection excessive dark colored cerumen was observed in 108 (9.2%) screened ears affecting 86 (14.6%) screened children in at least one ear. On immittance and pure tone screening 349 (59.2%) children had all measures within normal limits; 139 (23.6%) children failed one immittance measure only; 52 (8.8%) failed immittance screening; 9 (1.5%) failed pure-tone screening and 41 (6.9%) failed both immittance and pure-tone screening. A description of the hearing conservation program that was developed is included. Most findings are consistent with data reported in other studies, however the number of children with mild to moderate sensorineural hearing losses is below that expected from the literature. Replication of this study in other Mexican populations, follow up research on the impact of early detection, and the short and long term impact of the hearing conservation program implemented for school-age children from zone 34 is recommended