Plessimeter

Plessimeter (from Greek plesso-I strike and metron-measure), a special small plate used in percussion. The plessimeter was introduced in 1826 by Piorry with the aim of reducing the spread of sound along the surface of the percussed body, which is observed when directly tapping it with a finger or hammer, and with the aim of increasing the spread of sound in depth, thereby making it louder. When tapping, the plessimeter must fit tightly against the percussed body. The most common forms of plessimeter are a four-sided, knee-shaped with a gradually tapering end and an oval shape. The length of the four-sided plessimeter should not exceed 5 cm, and its width should not exceed 3 cm; for a round plessimeter, its radius should not exceed 2 cm; the thickness of any plessimeter should be at least 1¹/₂-2 mm. Plessimeters can be soft (e.g., made of rubber) and hard (made of glass, metal, ivory, celluloid). It is more advisable to use a hard elastic plessimeter, since with it more of the force of the blow goes deep and the percussion tone becomes more distinct. Among hard plessimeters, the celluloid or ivory plessimeter is most convenient (the glass plessimeter is brittle, the metal one is unpleasant for the patient). A plessimeter can be successfully replaced by the examiner's own fingers (see

Percussion).