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An audiometer is a machine used for evaluating hearing acuity.

An audiometer is a machine used for evaluating hearing acuity. They usually consist of an embedded hardware unit connected to a pair of headphones and a test subject feedback button. This device typically transmits pure tones to the headphones of the test subject at varying frequencies and intensities, and records the subject’s responses to produce an audiogram of threshold sensitivity.

I recently took a hearing test in a professional facility, and I received the results in the form of an audiogram. I decided to try to make a similar device because the principle of operation of the device is quite simple. After a short research on the internet I found applications that use the sound card of the PC for this purpose, but my goal was to make a practical stand-alone device. I found idea for this type of device on the Arduino forums by a user named “cstram” and decided to make it with some modifications depending on the hardware I had at the time. In this case, the Arduino is an input-output unit that generates tones with different frequencies and intensity, and then displays the feedback results received from the person being tested, on a screen with a resolution of 8 x 8 pixels made up of 64 RGB LEDs. The screen displays two graphs in different colors, for the left and right ear.

The device is relatively simple to build, and consists of several components:

- Arduino Nano microcontroller
- 8x8 matrix consist of 64 RGB Leds with buit-in WS2812 chip. For a more interesting visual impression, I made a 3D printed grid
- 128x64 Oled display with SSD1306 chip
- Rotary encoder
- push button
- female earphone jack
- and small earphones

The device is powered by two lithium batteries connected in series, and a 7805 5V voltage stabilizer is placed at its output. This time I neglected the battery control and charging circuit because that part has been described several times before.”

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