Atherosclerotic Changes in Bloodstream Can Be Detected Audibly

The device works via a planar, circular head that is ideally adapted to be placed against an eye socket of the patient. A microphone in the head detects an acoustic signal from the cerebrovascular system and converts the acoustic signal to an electrical signal; a filter then passes only a portion of the electrical signal having a frequency in a range between 350 Hz and 1,800 Hz as a filtered electrical signal, so as to eliminate extraneous signals due to other than vascular flow.

Key listening points for use with the device include the ophthalmic-orbital window, where turbulence can be heard from the ophthalmic and internal carotid arteries; the temporal window, slightly above the zygomaticus, where turbulence can be heard from the middle cerebral, internal carotid, and the anterior and posterior cerebral arteries; and proximate to the foramen magnum, above the cervical bifurcation of the common carotid artery.

The headset has an earpiece with a speaker for converting the filtered electrical signal to an audio signal so as to detect the turbulent flow in the cerebrovascular system of the patient. A volume control, mode selector (filtered or unfiltered), and an output port for recording the turbulence sounds are fitted to the side of the device. The Stethotron is a product of ProTron Technologies (Alpine, NJ, USA).

Standard and electronic stethoscopes are designed to listen to heart and lung signals between 10 Hz and 300 Hz. But as waves at these frequencies do not travel in straight paths, and also represent a physiological sound, an uncertainty as to the point of origin may cause diagnosis errors.

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