Spectral Analysis of Korotkoff Sounds

Ware, Ray W.; Anderson, Wallace L.

doi:10.1109/tbme.1966.4502433

Cited by 23 publications

(6 citation statements)

References 6 publications

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“…Maurer and Noordergraaf (1976) also estimated that 90% of the sound energy was contained in the frequencies lower than 25 Hz. Ware and Anderson (1966) employed spectral analysis to look at the overall frequency patterns of the sounds and showed that the main differences between the phases were above 100 Hz. Our results using the JTFA approach show that the murmur of phase II which separates phases I and III is much greater than this (figure 3), and that the higher frequencies can extend to 400 Hz.…”

Section: Discussionmentioning

confidence: 99%

“…There is also little consistency in the way measurements have been performed and the biomedical signal analysis techniques that have been employed make it difficult to compare the findings of the different studies reported in the literature. There is, however, consensus that the sounds are low frequency with energies contained within 600 Hz (Rauerkus et al 1966, Ware and Anderson 1966, McCutcheon et al 1969, Maurer and Noordergraaf 1976, Cozby and Adhami 1993, Allen and Murray 1997. Such simple analyses may miss potentially useful clinical information (O'Sullivan et al 2002) giving justification for more sophisticated and advanced techniques to look at the subtle changes in combined time and frequency information for the individual sounds.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of the Korotkoff sounds using joint time–frequency analysis

Allen

Gehrke²,

O’Sullivan

et al. 2003

Physiol. Meas.

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The sounds associated with the five classical Korotkoff phases are clinically important for measuring systolic and diastolic blood pressures. The frequency ranges of the sounds have already been described simply using the overall peak frequencies within each phase by Fourier methods. However, such analysis may be missing potentially useful clinical information. The aim of this study was to compare features associated with the different phases of the Korotkoff sounds obtained during blood pressure measurement using a joint time-frequency analysis (JTFA) technique. A single operator recorded Korotkoff sounds from 25 healthy subjects using a measurement system comprising cardiology stethoscope, microphone, amplifier and recording system for computer sound digitization, and a MiniDisc system for playback to the cardiologist for Korotkoff phase classification. We have shown that using this system the phase classification by the cardiologist is repeatable, with no significant differences found in the number of sounds allocated to phases on two separate recording assessments. The digitized sounds were processed using a MATLAB-based short-time Fourier transform JTFA technique and differences in time, frequency and amplitude characteristics between the phases compared. It was found that on average, phase III had the largest overall amplitude and high frequency energy. Phase II had the greatest high frequency component and longest murmur, and was visibly the most complex phase in terms of time and frequency content. In contrast, phases IV and V had the lowest amplitude and frequency components. Overall, the statistically significant transitions between phases were: phase I to II with increases in high frequency (224 to 275 Hz) (p < 0.01) and sound duration (49 to 98 ms) (p < 0.0001), II to III with a significant decrease in sound duration (to 37 ms) (p < 0.0001), III to IV with decreases in maximum amplitude (0.95 to 0.25), highest frequency (262 to 95 Hz), and relative high frequency energy of the sounds (0.61 to 0.10) (all p < 0.0001), and IV to V with decreases in the maximum amplitude (0.25 to 0.13) (p < 0.0002) and high frequency energy (0.10 to 0.03) (p < 0.005). This study has demonstrated that joint time-frequency analysis of Korotkoff sounds was able to identify characteristic differences associated with the different phases classified by the expert cardiologist. Ultimately, exploiting the joint time and frequency characteristics of the sounds may improve blood pressure measurement and help to assess the stiffness of the peripheral arteries.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterization of the Korotkoff sounds using joint time–frequency analysis

Allen

Gehrke²,

O’Sullivan

et al. 2003

Physiol. Meas.

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“…Continuing to deflate the cuff, the duration of This setup allowed the computer to acquire, in parallel and without intervals during which the artery is open becomes higher and the interference, the same information perceived by the operator and tones are increasingly clear. This value was considered 4000Hz) [14,15] and sampled. The signals were amplicomes lower than the minimum pressure in the artery, the vessel remains open and tones disappear.…”

Section: Methodsmentioning

confidence: 99%

The Arterial Pressure Auscultatory Method

Corazza

Fabbiani

Marras

et al. 2006

High Blood Pressure & Cardiovascular Prevention

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“…At this point, the pressure in the cuff corresponds to the systolic pressure. After the pressure decreases further, the doctor will continue hearing the sound (with different characteristics) [1]. And at some point, the sounds will begin to disappear.…”

Section: Fig 3 Blood Pressure Block Diagrammentioning

confidence: 99%

Blood pressure measurement using Korotkoff sounds

Mahajan¹,

Thakurdesai²,

Modak³

et al. 2015

2015 International Conference on Industrial Instrumentation and Control (ICIC)

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Blood pressure and heart rate measurement are the most commonly used parameters to determine the health of a person. This paper aims at implementing a blood pressure monitoring system using a novel approach. A digital stethoscope is designed and implemented which is used to record the Korotkoff sounds, which is utilized by the blood pressure module to determine the blood pressure of the individual. The signals from these modules are captured via DAQ cards and fed to a computer for further processing using LabVIEW software. The system shows invariance to external noise due to appropriate filtering and signal conditioning. The prototype possesses advantages of having small volume, low power consumption, and real time processing capabilities.

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Spectral Analysis of Korotkoff Sounds

Cited by 23 publications

References 6 publications

Characterization of the Korotkoff sounds using joint time–frequency analysis

Characterization of the Korotkoff sounds using joint time–frequency analysis

The Arterial Pressure Auscultatory Method

Blood pressure measurement using Korotkoff sounds

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