Introduction: Correct breathing is a fundamental condition for adequate vocal production. Respiratory dynamics are able to modify the growth of facial mass and lingual posture, i.e., of the skull, the mandibular one. For this reason, infant mouth breathing can cause hoarseness. Materials and methods: We evaluated the actual changes in the characteristics of the voice and articulation of language in a group of subjects affected by adenotonsillar hypertrophy (grade 3–4), with frequent episodes of pharyngo-tonsillitis who underwent adenotonsillectomy. Our study included 20 children—10 boys and 10 girls—aged 4 to 11 years who had adenotonsillar hypertrophy and pharyngotonsillitis episodes exceeding 5–6 per year in the previous 2 years. The control group (Group B) included 20 children—10 boys and 10 girls—aged 4 to 11 years (average age of 6.4 years) who had not undergone surgery and shared the same degree of adenotonsillar hypertrophy as those in Group A but who did not experience recurrent pharyngotonsillitis episodes. Discussion: The hypertrophy of adenoids and tonsils significantly impacted breathing, vocal function, and speech articulation. All this is responsible for a state of tension in the neck muscles, which at the level of the vocal tract causes hoarseness. The changes objectively observed in our study in the pre- and post-operative phase demonstrate how adenotonsillar hypertrophy is responsible for an increase in resistance to the passage of air at the glottic level. Conclusions: For this reason, adenotonsillectomy has an impact on recurrent infections and can also lead to an improvement in speech, breathing, and posture.