Images(2)

Dunlap-type voice key

Dateafter 1918

Inventory NumberWJ0127

ClassificationVoice Key

Subject

Maker American

Inventor Knight Dunlap 1875 - 1949

Cultural Region

Dimensions30 × 22.7 × 24 cm (11 13/16 × 8 15/16 × 9 7/16 in.)
membrane diam.: 9.6 cm (3 3/4 in.)

Material

DescriptionA heavy cast-iron tripod supports an horizontal and adjustable steel rod on which is attached a thin metallic circular membrane. When one spoke in front of the membrane, the air vibrations caused by the voice were communicated to a pivoting contact stylus. A screw can adjust the amplitude of the vibrations. The mechanical movements of the stylus is transformed into electrical signals, stopping time on a chronoscope. The whole voice key was electrified.

Signedunsigned

FunctionDesigned by Knight Dunlap for use with Dunlap chronoscopes. It is similar to Roemer's voice key, but unlike Roemer's, it does not have an electromagnet and bell attached. Such voice keys were used to register a reaction by voice (a time measurement of mental acts): whenever the membrane vibrates because of a voice response it touches a nearby contact, electrically stopping a hand on the chronoscope.

ProvenancePsychology Department, William James Hall, Harvard University.