Abstract: A computer-implemented method includes: providing backing track audio data, wherein each backing track includes information of at least: song tempo, tonal content that is synchronized with the backing track audio, selecting a song, receiving a real-time audio signal of the user's performance, estimating parameters, based on the audio signal, including at least: playing activity of the user, wherein detecting whether the user is producing any sounding notes with a musical instrument, tempo of the user's playing, and playing position of the user within the selected song, estimating the reliability of the estimated tempo and play position of the user, wherein a value of the reliability represents the probability that the amount of error in the estimated user tempo and play position is sufficiently small, and when the estimated reliability of the user position and tempo is sufficiently high, start playing the backing track at the user position and tempo.

Abstract: A system and method for displaying information on mobile devices via a user interface (UI) includes an overlay structure on top of an application or web page which shows content related to a product or service. The overlay structure on top of an application or web page showing content related to the promoted product enables user action such as purchasing the product or service without taking the user away from the original view used for accessing the information.