These wooden heads are in the collection of the National Institute of Standards and Technology Museum. The NIST has recently posted a selection of curious and mysterious scientific instruments and artifacts, such as a frequency-analysis recording on a 17 year cicada, a "rectangular wood-framed instrument with nine terminals on top," and a "wood box with one dial at top." Indeed, according to the NIST, they "sometimes have only minimal information about the artifacts" and are asking your help to fill in the details.
