If you already know what you are looking for, this free but powerful tool will surely satisfy your needs.

Sonic Retro is a great tool for Android that supports to create, edit and combine audio files and import or export two files at once. The application supports uncompressed WAV and MP3 files and allows to save audio content on the device microSD card or through the built-in memory.
The interface offers all the main functions and the audio files quickly appear in the main window 99d5d0dfd0