A musical transcription is musical notation for an existing piece of music that had been previously unnotated. Musicians often disagree about what should be called a “transcription” and what is an “arrangement”. Usually transcriptions are a direct notation of the source, whereas a musician who makes an arrangement may insert new interpretations into the music (i.e. changing the instrumentation, reharmonization, or even new sectionalization of the piece as with cover songs). A transcription, as Klapuri writes, would require that the pitch, timing, and instrumentation of all sound events to be resolved; difficult as this may be for some cases, this goal is usually redefined such that a transcription constitutes the notation of as many of the constituent sounds as possible or some well-defined part of the music signal (i.e. the dominant melody or the most prominent drum sounds).