References
- Liu X, Xu L. Nonsyndromic hearing loss: an analysis of audiograms. Ann Otol Rhinol Laryngol 1994; 103: 428–33
- WHO. Grades of hearing impairment. Hearing Network News 1991; 1
- International Organization of Standardization. ISO 389–1991. Acoustics—Standard reference zero for the calibration of pure-tone air conduction audiometers. CH-1211, Geneve 20, Switzerland