Audio Tester is a free Android app developed by BARUM that allows you to test the audio devices connected to your smartphone. With this app, you can test the left and right sound of a stereo audio device, check the time difference between when the white ball passes 0 milliseconds and when the tick sound actually sounds on the audio device with the delay test, and test the frequency range of your audio device with the frequency test.

The app is straightforward to use, and the tests are easy to perform. The delay test is especially useful for checking the delay of wireless connections such as Bluetooth. However, it is important to note that testing at high volumes can harm your ears, so it is recommended to turn down the volume before doing the frequency test.

Overall, Audio Tester is a useful app for anyone who wants to check the performance of their audio devices. It is simple, free, and does not require any personal information or contact with the developer.