To discuss the relationship between perceptual diagnosis of lateral misarticulation (LM) by sophisticated listeners and its physical correlates, two experiments using continuous speech /(sh)/ were performed. Experiment 1 was a comparison of the spectral envelopes of normal speech /(sh)/ with those of LM. Experiment 2 was the detection of similarities based on auditory impressions of sophisticated listeners between LM and normal speech /(sh)/ with specific spectral envelope bands replaced. The stimuli for experiment 2 were resynthesized from modified spectral envelopes by using the LMA synthesizer. These experiments showed the following. (1) Spectral envelopes of the LM are flat in the frequency band above approximately 4 kHz, whereas normal speech presents a plateau. Moreover, there is a substantial peak around 3.2 kHz in the LM, which varies with time almost periodically, a variation not present in normal speech. (2) The replacement of the spectral envelope between 2.5 and 4.5 kHz of normal continuous speech with that of LM resulted in a remarkable increase in similarity to LM based on auditory impressions. These facts suggest, that the spectral envelope characteristic of the LM is a near-periodical variation around 3.2 kHz.