Dr. Evelyn R. Klein, PhD, CCC-SLP, BCS-CL, is a professor and clinical supervisor at La Salle University in the Department of Communication Sciences and Disorders, where she teaches and directs the Castle Lab for clinical evaluations. She also continues to work in private practice. Dr. Klein holds professional licensures in speech-language pathology and psychology. Her areas of specialization include selective mutism, autism, language-learning disabilities, acquired language disorders, stuttering, and counseling. Dr. Klein is a Fellow of the American Speech-Language-Hearing Association and has supervisory certification in special education. She received the Lindback Distinguished Teaching Award and the Distinguished Faculty Scholarship Award from La Salle and the Clinical Achievement Award from the Pennsylvania Speech-Language-Hearing Association. Recent publications include ECHO: A Vocal Language Program for Easing Anxiety in Communication; EXPRESS (Expanding Receptive and Expressive Skills through Stories; More Than Fluency; and Acquired Language Disorders: A Case-Based Approach (4th edition). She is a contributor and expert reviewer for academic journals and serves on the Scientific Advisory Board of the national Selective Mutism Association.

Cesar E. Ruiz, SLP.D, CCC-SLP, BCS-S, is a Professor Emeritus at La Salle University in the Department of Communication Sciences and Disorders. He received his SLPD degree from Nova Southeastern University in Ft. Lauderdale FL. Dr. Ruiz is a licensed and certified speech-language pathologist. He holds Board Certification in Swallowing and Swallowing Disorders and is a Voice Clinical Specialist. His areas of specialization include selective mutism, dysphagia, voice disorders, and bilingualism. Dr. Ruiz is an author of ECHO: A Vocal Language Program for Easing Anxiety in Conversation. He co-directs the CASTLE Center at La Salle University in Philadelphia. The CASTLE Center is a specialized comprehensive assessment center where children with Selective Mutism are evaluated. Dr. Ruiz has pioneered the use of vocal control to help children with Selective Mutism. He has presented on topics related to his area of expertise locally, nationally, and internationally.