Bruit spectral analysis provides an improved noninvasive method of quantifying the severity of carotid stenosis, and the method of Lees estimates the residual luminal diameter. Although the analysis required is complex, the test can be easily performed using the Spectraview, a microcomputer-based device which records and processes the sound information. The present study evaluated 44 cervical bruits in patients and found that in 84 percent of the vessels the estimated luminal size was within 1 mm of the angiographic lumen. Although substantial experience is required to obtain the maximum diagnostic accuracy, work with the technique during 18 months indicates that is provides more information from arterial bruits thn traditional phonoangiography.