Various preordain situations result in a disease or injury to people and deprive them off with their natural ability to communicate verbally. The diseases which affect the voice and language of people may include congenital impairments, such as cerebral palsy, intellectual impairment and autism, and acquired conditions, such as amyotrophic lateral sclerosis and Parkinson’s disease. As larynx is the main organ for voice production, any illness which results in the removal of larynx, i.e, laryngectomy, will result in loss of voice. The illness may be malignancy of larynx or pharynx or severe laryngeal stenosis. The afflicted people find other means like alaryngeal methods, which include hand written notes, by simple actions (like hand or facial gestures), with esophageal speech or with aid of devices like electrolarynx or tracheo esophageal prosthesis.

The means of sign language require the use of hand- gestures and/ or facial expressions. Sign language is a mode of communication for patients who are affected since birth. In recent years, the technological advancement in the field of electro-medical devices for life support, implantable biomedical devices, and wearable medical devices have successfully provided artificial abilities to the afflicted people related to any kind of disability or impairment. The electro-medical devices, implantable biomedical devices, and wearable medical devices may include but are not limited to an artificial pacemaker, ventricular assist device, bioartificial liver, wearable dialysis device, implantable artificial kidney devices, artificial limbs, and sensory devices, such as hearing aids, optical lenses etc. The electro-medical devices when used in combination with multiple speech synthesis techniques provide an option for the people with speech and language impairment, to communicate audibly. Such electro-medical devices are known as augmentative and alternative Communication (AAC) devices or speech generation devices (SGDs). In the speech synthesis techniques, the spoken language is generated by a machine on the basis of a written input.