Whistle Detector is free application that is used for detecting whistle. You can customize you app from the settings. You can choose different color for your theme.

The app is using Foreground Service that is started once the application is about to be closed and is constantly listening for whistles. This means that the app will consume large amount of your phone/tablet battery. For people who are more knowledgeable there is 'Analyser' section in the settings. From there you can choose different configurations, but if you don't know what you are doing you can make the app detect false whistle detection or prevent any detection at all. In that case simply press the 'Reset' button to use the default configurations.