What is a question about this article? If the question is unanswerable, say "unanswerable".

Bell's father, grandfather, and brother had all been associated with work on elocution and speech, and both his mother and wife were deaf, profoundly influencing Bell's life's work. His research on hearing and speech further led him to experiment with hearing devices which eventually culminated in Bell being awarded the first U.S. patent for the telephone in 1876.[N 4] Bell considered his most famous invention an intrusion on his real work as a scientist and refused to have a telephone in his study.[N 5]

What did Bell never put in his study?
telephone