Maxillary expansion is a frequently performed orthodontic procedure and significant number of patients present with altered vocal function after maxillary expansion. Our knowledge of these changes auditory and perceptual manifestations is acquired from relatively small-scale investigations that made use of a variety of methods. To further understand the changes occurring across different measurement domains, we combine data from auditory, perceptual, and instrumental assessments and this systematic review was conducted to study the impact of maxillary expansion on speech and the outcomes of this study will assist with pre-treatment and interdisciplinary counselling for orthodontic patients undergoing expansion.