Crystal Hearing Aid is a free Android app developed by The Sun App Developers. It falls under the Multimedia category and specifically in Music & Radio subcategory. This application amplifies sound from the microphone straight to your headphones with filtered and clear voice to give you enhanced hearing.

Crystal Hearing Aid has some features that make it a standout app. Firstly, the user can select the right and left ear volumes to customize the sound for each ear. It also applies a noise filter to the mic input to ensure that the sound is clear and not distorted. Additionally, it amplifies sound without distorting its quality, and high sample rates are supported.

It is important to note that the app is ad-supported to generate revenue for the developers. Also, the app is not approved as a medical device or software and cannot be used as a hearing aid with a doctor's prescription. Therefore, users should use common sense and caution when using this app. It is advisable to consult a doctor before using this application.