Experienced cardiologists can usually recognize pathologic heart murmurs with high sensitivity and specificity, although nonspecialists with less clinical experience may have more difficulty. Harsh, pansystolic murmurs of intensity grade > or = 3 at the left upper sternal border (LUSB) are likely to be associated with pathology. In this study, we designed a system for automatically detecting systolic murmurs due to a variety of conditions and examined the correlation between relative murmur intensity and likelihood of pathology. Cardiac auscultatory examinations of 194 children and young adults were recorded, digitized, and stored along with corresponding echocardiographic diagnoses, and automated spectral analysis using continuous wavelet transforms was performed. Patients without heart disease and either no murmur or an innocent murmur (n = 95) were compared to patients with a variety of cardiac diagnoses and a pathologic systolic murmur present at the LUSB (n = 99). The sensitivity and specificity of the automated system for detecting pathologic murmurs with intensity grade > or = 2 were both 96%, and for grade > or = 3 murmurs they were 100%. Automated cardiac auscultation and interpretation may be useful as a diagnostic aid to support clinical decision making.

Frequency selective scattering of water-borne acoustic waves by the rough sea surface ͑Bragg scattering͒ has been observed, in particular during the Critical Sea Test series. The directional nature of the gravity wave spectrum observed by Mitsiyasu, Donelan, Banner and others implies that the interface scattering will be directional, that is, depend upon azimuth relative to the receiver. During the ocean exercise Critical Sea Test 4, Bragg scattering was observed at 250 Hz over a wide range of azimuths using a linear hydrophone array with approximately one degree azimuthal resolution. The amplitude of the Bragg scattering and its dependence on azimuth closely matched model predictions based on the Donelan 2-D wave spectrum, first-order perturbation theory and a normal mode reverberation model.