Hello and welcome to the TranslatorsCafe.com
Channel! In this video I will show you how to record the sound of your heart using a
stethoscope and a microphone connected to it. OK, first, the obligatory disclaimer. Of course I am not a doctor and cannot give any medical
advice. The device shown here cannot be used for any diagnostic purposes. Of course, only
medical professionals can listen to the heart sounds and make diagnoses. Ordinary mortals
like me cannot do such things. And of course if something goes completely wrong, for example,
the mains voltage appears on the stethoscope head or microphone and your body appears grounded
at this time, this device can kill you. In short, if you are going to repeat these experiments,
you have to know what you are doing. Recording heart sounds is relatively easy.
You will need a good microphone capable of recording low frequencies, an inexpensive
stethoscope, a recording device and headphones. It is also possible use a piezoelectric buzzer
or transducer as a contact microphone. I took it from an old smoke detector. The
stethoscope is not necessary if you will use the contact microphone. I tried both and discovered that the condenser microphone
combined with the stethoscope worked better than the contact microphone.
We will attach the microphone to the chest piece of the stethoscope using a short piece
of tube. The bell part of the stethoscope will be used for recording. The diaphragm
can be also used. In ordinary acoustic stethoscope the diaphragm is used to filter low frequency
sounds and to emphasize high frequency sounds at the expense of their amplitude. However,
in our case we can use software to amplify various frequencies and to remove some unwanted
high frequencies. Now, some theory. Heart sounds are generated
by beating heart, mostly by shutting heart valves, and the flow of blood through the
heart. The process of hearing these sounds for diagnostic purposes is called auscultation.
In healthy adults there are two main heart sounds that are called first and second heart
sound S1 and S2. The first sound is produced when atrioventricular valves (mitral or bicuspid)
and tricuspid valve are closed and the second sound is produced when semilunar (aortic and
pulmonary) valves are closed. Other sounds may be present if a person is not healthy. To hear heart sounds a stethoscope is pressed
to the chest at locations labelled with M (Mitral), T (Tricuspid), A (Aortic), P (Pulmonic)
and E (Erb’s point, the best for S2 auscultation). Now we will connect the stethoscope head with
the microphone to the recording device. Our electronic stethoscope is now ready for
recording my heartbeats. Later I will view the waveform of the recorded sound of my heart.
It is also possible to view its spectrogram that is a visual representation of the spectrum
of frequencies in a sound vs. time. The horizontal axis represents time, the vertical axis represents
frequency and a third dimension indicating the amplitude is represented by the color
of the image. For recording and playing back I will use
Thinklabs Phonocardiography powered by Audacity software that is free and can be downloaded
from thinklabs.com. We tried to show that it’s pretty simple
and inexpensive to record your heart beat sound, to listen and even to view it. Thank
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