Guitar Tuner is a Qt Quick example application that demonstrates the integration of Qt audio interfaces. The application can be used to tune guitar strings by analysing the audio recorded by the device microphone.
This example is hosted in a Nokia Developer Project, where you can find additional documentation, discover recent revisions, and contribute to the project.
This app is created step-by-step in the Nokia Developer Hands-on Labs as well. You can build the logics of this app by yourself by following this tutorial: http://www.developer.nokia.com/document/Mobile_Hands-on_Labs/Qt/MobilityMMAudio/ and also create the Qt Quick UI for this app by following this tutorial: http://www.developer.nokia.com/document/Mobile_Hands-on_Labs/Qt/QtQuick/.