We have presented a new type of recording apparatus which possesses distortion simulating that of the human ear. This permits strict correlation between clinical cardiology and phonocardiographic records. In addition we have established an even base line which permits accurate timing of the beginning and end of heart sounds. The fundamental characteristics of the first and second sounds are described.

We suggest that further phonocardiographic studies be performed along these lines. This may be expected to yield more fruitful results than has hitherto been possible.^{∗Since offering this paper for publication, our attention has been called to the work of Posener and Trendelenburg (Zischr. f. Kreislaufforsch. 21: 15, 1929) who employed a principle quite similar to that offered here. To our knowledge they have not described their technic in detail.}