The present invention relates to a method which aims to improve data security in mobile payment transactions. The audio receiving module calculates the strength of the at least one signal, the locator module determines whether each of the strength exceeds a predefined value and determines the directionality of the at least one audio signal in accordance with the strength of the at least one audio signal. The user interface, among other functions, detects an embedded code in a media file from a streaming content server. In response to the request to view the supplemental information area, a view of the document is rendered at the client such that the document does not fill the canvas. The constant power regulator boosts an input voltage and secures a certain power. The ink ejection port is formed substantially centrally on the wall with a rim surrounding it.