Lateral misarticulation (LM) is a type of misarticulation in which the tongue dorsum contacts the hard palate continuously, forcing air out from the retromolar region to the buccal groove. To discuss the relationship between this articulatory gesture and acoustical characteristics, physiological experiments and acoustic analyses were performed during the production of sustained |sh| in functional articulation disorders and cleft palate misarticulation. Electropalatography, lateral radiographic film examination, and airflow measurements were used to analyze physiological features. Speech samples were analyzed using the improved cepstrum method to observe acoustical features. The following results were obtained: (1) The tongue dorsum maintained broad contact with the hard palate during LM production. (2) Air flow was directed from one side of the posterior region of the hard palate. (3) The spectral envelopes of the LM are flat in the frequency band above around 4000 Hz, whereas normal speech has a plateau. Moreover, there is a substantial peak around 3.2 kHz in the LM which varies with time, a variation not present in normal speech.