• The speech of echolalic autistic children is (1) specifically lacking in appropriate use of expressive-intonational features, but (2) the echolalic child's clear articulation of words and phrases indicates that discrimination of phonemic features is intact. The impairment in aphasic disorders is just the reverse. Failure to attend to auditory stimuli and the characteristic language disorder are among the most consistent findings in autistic children; they could be related.
Discrimination of differential stress emphasis is the way the normal young child extracts major morphemic word stems and syntactic features from environmental speech; this may be a primitive perceptual function of brain stem auditory centers. The brain stem auditory system is especially vulnerable to perinatal injury. Damage to this system is an example of the kind of lesion that might lead to behavioral handicaps without neurological signs.
Simon N. Echolalic Speech in Childhood AutismConsideration of Possible Underlying Loci of Brain Damage. Arch Gen Psychiatry. 1975;32(11):1439-1446. doi:10.1001/archpsyc.1975.01760290107013