The famous Scottish inventor Alexander Graham Bell's mother was deaf. His father was a speech teacher who used a system of symbols to teach speech to deaf. The family later moved to the United States and Alexander Graham Bell was interested in speech teaching from a young age. He had in fact learn his father's symbol system and was teaching deaf children at schools. He later established his own school for deaf children in Massachusetts and also taught about speech at Boston University. However, he wanted to come up with a better way to teach the deaf and he invented the graphophone with this intention.
The graphophone (sometimes referred to as a phonograph) is a device that records and replays speech. It was based on Edison's phonograph, the first device to both record and replay recorded sound. Bell made improvements to the device, made it more practical and also improved the quality of the recorded sound. But his work remained partly unfinished due to other priorities. He did however have other projects to help the deaf. For example, he tried to visually record sound waves. And his initial work on the graphophone contributed to his invention of the telephone in 1876.
Bell really wanted to educate the deaf people, and was very interested in doing so. He improved the phonograph and named it the graphophone. The sound vibrations created on the disc helped the deaf to learn by reading those vibrations. The money he earned from selling this invention also allowed him to further continue his studies to help the deaf.