NoiseTube was created with the purpose of turning smartphones into mobile noise level meters. The app allows citizen scientists to participate in the collective noise mapping of their city or neighborhood. NoiseTube has three features: measure noise, localize it and tag it. Tags include the level of annoyance and the source of sound, such as an airplane. The collected data is wirelessly sent to the NoiseTube server in real time. Once the data has been uploaded to NoiseTube’s Web site, users can check their sound trajectory on Google Maps.