A man wearing an ear trumpet is an unusual subject for any photo. Much effort was made to deliberately conceal ear trumpets … this ambrotype by contrast suggests a proud owner.
Ambrotypes developed the photograph directly onto a glass plate coated with silver salts and backed with a black varnish. Because they were so fragile this needed mounting behind another piece of glass which was often then mounted in a metal frame. In this example the embossed leather box case holds an ornate gold metal frame with finely decorated velvet in the opposite face.
The resolution of this picture has never been fine enough to identify a specific type of ear trumpet and I have had a suggestion that this might not even be one. In the early days of photography exposure times were tediously long and subjects needed to stay motionless for minutes at a time. To help their clients keep still, photographers made use of posing supports to anchor them (see here for examples). So could the protuberance over this man’s ear is the visible edge of a posing support? I cannot say for sure one way or another, but it is certainly an interesting possibility and one I thought worth sharing.