# What range of frequencies can be generated by blood flow

1. Aug 28, 2009

### tarek1984

hi

i was trying to prepare for a project based on passive sensing of sound waves
By using natural sound created naturally by blood flow may be turbulence flow of blood in blood vessels

So i want to know how to calculate the frequency ranges which can be generated in the human body

2. Aug 28, 2009

### Electrocuted

First of all I think you should rephrase your question, it sounds a bit odd. Are you trying to produce sound by the blood flow in the body which allows a person to sense heart beat? Or are you trying to use the natural heart beat that creates blood flow to detect sound waves?

From a very macro point of view, the frequency can easily be the beats per second of your heart. Thus the range would naturally be the maximum known heart rate to the minimum known heart rate of a human being which can be very confusing.

Increased rush of blood to the extremities of the body allows increased brain activity by releasing chemicals in the brain e.g. Endorphins; which might cause the detection of sound waves appear to be lower in frequency. For example, try listening to music when you have just woken up in comparison to listening to the same piece after running 3 km. You would sense a slight difference in the tempo of the sound due to the BRAIN ACTIVITY rather than the flood of blood in the vessels.

As for a more detailed example you would have to resort to hemodynamics - a study of the blood flow in the body. However, the turbulence of blood in a human body has nothing to do with the sense of sound, rather to increase the brain activity by sending more blood to the head. Therefore your project should focus on brain function rather than blood.

3. Aug 28, 2009

### tarek1984

Sorry my quistion was not clear.I am tring to make something like ultrasound sonar but uses sounds created in the body .Heart beat is about 2Hz or grater but not in the audo rang but you can lesten to this sound.I think that this sound is created by the flow of blood

4. Aug 30, 2009

### Andy Resnick

Interesting question- AFAIK, the sound you hear from a heartbeat is from the turbulent flow within the heart (as well as the valves opening and closing) during filling and ejection. Thinking about it, I'm not sure why we can hear the sound of air going into and out our lungs during a breath!