It is an application program that in real time displays the spectrum of the voice input from your Android phone's microphone. A horizontal axis is a music scale. A display position can be adjusted by dragging horizontally. Scaling of the display range of a scale can be carried out in pinch zoom operation.
Get the setup package of Audio Spectrum Monitor 1.5.1 that is free and have a look at users' reviews on Droid Informer. The app is designed for Android 4.0 and higher. This application is totally safe for downloading. TadaoYamaoka is the creator of the tool that can be found in the Music & Audio category.