Set of eight tuning forks, in black leatherette case, no maker, 1935-1950.

These tempered steel instruments tested hearing. Each tuning fork consists of a stem with two prongs. They produce a nearly pure musical tone when struck. Each maintains a constant pitch when struck. The fork was held near the ear. The patient indicated whether he or she could hear it ringing. The set of eight tuning forks varied in pitch from the bottom to the top of the ordinary range of the ear. This let the doctor determine the range of frequencies the patient could hear. The upper range of human hearing falls significantly with age. Even teenagers can hear some high-pitched tones that adults in their 20s cannot.