Not having a good performance with the preamp module, I went to a store specializing in electronics, looking for a module that detects the sounds. The only module I found for that purpose was ky-038, which is a module that uses an electret microphone to pick up sounds, ranging from 100 Hz to 10 KHz, covering the detection range of the human voice, incorporates itself into an operational comparator amplifier, the LM393. This module works from a voltage of 3.3V and offers an analogous output for the range of 1Vpp.

When connecting and testing with the horn, an improvement in the detection of sounds is perceived, having a less saturated sound and without noise.

When testing with the "bone transducer", it is possible to perceive the sounds, although somewhat weak. The part of this prototype was satisfying, since with simple elements we could perform the corresponding tests, and see that the idea is functional.

• Have a true bone transducer, since the vibrator motor that we used for the tests, was not designed for this purpose.
• Better the stage of audio amplification, having an audio amplifier that delivers more output watts and a low energy consumption.
• Design a case with 3d printing, in which all the components are put and be more comfortable to use.