Beltone "Sonata" Behind-the-Ear Hearing Aid The Beltone "Sonata" behind-the-ear hearing aid was produced by the Beltone Electronics Corp. of Chicago, IL beginning in 1975. The hearing aid at the right was made in 1978. On the upper underside there is stamped the serial number "X96148" and the year "1978". The "Sonata" came with a directional microphone. The forward-facing microphone port is in the clear plastic above the ear hook. The black dot (upper center) is the rear microphone port. The words "Beltone" and "Sonata" are stamped on the left side of the case (right). | 
