11 and a half year old boy change voice may be normal, but also to be vigilant vocal polyps and other diseases caused, as well as papilloma and other diseases caused, is not normal. 1. Normal phenomenon: 11 and a half years old boys are mostly in puberty, there will be the phenomenon of the development of secondary sexual characteristics, there will also be the phenomenon of voice change, so 11 and a half years old boys change their voices may belong to the normal physiological phenomenon. 2. Vocal polyps: Vocal polyps are mainly due to improper or excessive vocalization and other factors, the main symptoms of children with hoarseness, voice changes, pronunciation fatigue. Children with vocal polyps may also experience discomfort in the throat and pain in the larynx when pronouncing words, which are abnormal phenomena. 3. Other: papilloma, laryngeal cancer and other diseases can also lead to the phenomenon of children with voice change, which is also abnormal. There may be other reasons for the 11 and a half year old boy to change his voice, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment under the guidance of the doctor.