Abstract: A portable sound processing device [1000] designed to retrofit a portable digital player (PDP) such as an iPod sold by Apple, Inc., includes a display [1201] for interacting with a user, a plurality of input devices [1103-1133] for receiving input from a user. The portable sound processing device [1000] has internal or external pre-recorded music which may be mixed with the live input from a musical instrument [3]. The processor [1000] may perform digital signal processing to change the pitch while keeping the tempo the same for pre-recorded music to match the key of the instrument being played. The tempo may be adjusted while not affecting the pitch allowing a musician to practice a song at a slower pace. It may also highlight or remove a specific instrument for practice purposes. The result is a portable signal processing device [1000] which aids music transcription, learning and study.

Abstract: A portable sound processing device [1000] designed to retrofit a portable digital player (PDP) such as an ipod sold by Apple, Inc., includes a display [1201] for interacting with a user, a plurality of input devices [1103-1133] for receiving input from a user. The portable sound processing device [1000] has internal or external pre-recorded music which may be mixed with the live input from a musical instrument [3]. The processor [1000] may perform digital signal processing to change the pitch while keeping the tempo the same for pre-recorded music to match the key of the instrument being played. The tempo may be adjusted while not affecting the pitch allowing a musician to practice a song at a slower pace. It may also highlight or remove a specific instrument for practice purposes. The result is a portable signal processing device [1000] which aids music transcription, learning and study.