I visited many sites and did lots of Google search but I didn't get my answer.

In this link I read the article about how Sgnl works. and here's some text:

"Sgnl will generate vibration through its Body Conduction Unit (BCU) which transmits the vibration through your hand to your fingertip. When you place your fingertip to your ear, the vibration echoes to create amplified sound within the closed space of your ear."

I am interested to know the physics concept behind how the BCU makes vibrations and the vibrations is converted to sound. As described in the text this device allow us to hear without wire and any other device on ear My question is how? Is it just sending sounds through solids or It has a complexity Why isn't energy lost by materials in the body? Why is difference a lot between input and output in range of 2000 Hz to 20000 Hz? Sound Quality Test


closed as unclear what you're asking by Kyle Kanos, honeste_vivere, Jon Custer, peterh, Yashas Jul 16 '17 at 2:55

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Without knowing anything specific about the BCU (which is likely proprietary in any case), we can say this much: The BCU is basically an ordinary speaker which has been optimized in some way to conduct sounds through solids (in this case, the body). The speaker creates sounds (i.e. vibrations) in your wrist, which travel through your hand and into your ear, where they can be picked up by your inner-ear fluid and bones (interestingly, this appears to mostly bypass the eardrum).

The fact that your ears can hear sounds conducted through your body is part of the reason your voice sounds so different when played back to you in a recording. The vibrations from your vocal cords are conducted to your ears along with the vibrations from the air they're already receiving. These two sound signals add together to produce an entirely different timbre inside your head than what actually comes out of your mouth.

  • $\begingroup$ @MohammadHadi Disclaimer: audio via conduction is tricky, since there are lots of fluids and soft materials in the body that tend to interfere with transmission of sound. These devices typically do not work as well as advertised. $\endgroup$ – probably_someone Jul 15 '17 at 7:15

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