| phonocardiograph | <apparatus> An instrument, utilizing microphones, amplifiers, and filters, for graphically recording the heart sounds, which are displayed on an oscilloscope or analog tracing. Linear phonocardiograph, a phonocardiograph that records all chest wall vibrations resulting from cardiac activity, with emphasis on low frequency vibrations due to its filter characteristics. Logarithmic phonocardiograph, a phonocardiograph that records only theoretically audible vibrations with emphasis on the higher frequencies due to filter characteristics designed to imitate the logarithmic frequency-intensity response of the human auditory apparatus. Spectral phonocardiograph, an instrument for recording the heart sounds in which the electrical changes created by the latter pass from a microphone through a series of filters, each of which is tuned to a particular frequency band; output from each filter activates a separate light source of brightness proportional to the intensity of the sound transmitted through that filter; the lights are arranged vertically in descending order of frequencies. A record is obtained by photographing the vertical row of lights. Stethoscopic phonocardiograph, a phonocardiograph that records all sound vibrations, audible and inaudible, conveyed by the stethoscope; however, very low frequency vibrations (in the range of body movements) are filtered out. (05 Mar 2000) |
|---|---|
| spectral | 1. Of or pertaining to a specter; ghosty. "He that feels timid at the spectral form of evil is not the man to spread light." (F. W. Robertson) 2. <optics> Of or pertaining to the spectrum; made by the spectrum; as, spectral colours; spectral analysis. Spectral lemur. <zoology> See Tarsius. Source: Websters Dictionary (01 Mar 1998) |
| spectral sensitivity | The reciprocal of the amount of monochromatic radiation that produces a fixed response. (05 Mar 2000) |