Three hundred seventy-one second graders in rural public schools were evaluated for thumbsucking, rest and swallow postures of the tongue, and articulatory placement and acoustic aspects of /s,z./. Significant relationships were observed between thumbsucking and lower dental or interdental rest and swallow postures as well as acoustic errors for /s,z/. The implications of these relationships are discussed.
Kellum, G. D., et al. (1994). Thumbsucking as related to placement and acoustic aspects of /s,z/ and lingual rest postures, International Journal of Orofacial Myology, 20 (1), 4-9.