Voice fundamental frequency in mentally retarded children

The electroacoustic vocal characteristics of 200 mentally retarded subjects were compared with those of 200 age- and sex-matched normal controls. The main results were: (1) mentally retarded subjects showed higher values of fundamental frequency which increased significantly as IQ decreased; (2) all groups showed an effect of age: the fundamental frequency decreased as age increased; (3) mentally retarded subjects showed a higher rate of various alterations such as biphonation, fundamental frequency shift and noise. These findings can be interpreted as the result of a neurophysiological immaturity in mentally retarded subjects.