Häälevaljusmõõtur koosneb huulikust ja diafragmast, mille taha on asetatud õrn mehanism, mis olenevalt diafragmale mõjuvast hääle valjusest juhib tavalisse männilauda puuritud aukudega 15-tollist hooratast.
A phonometer consists chiefly of a mouthpiece and diaphragm. Behind the diaphragm is placed a delicate mechanism which operates a 15-inch flywheel by means of which a hole can be bored in an ordinary pine board.
