At Boise State University we are attempting to create software for the automatic transcription of music from audio recordings. Current systems do a good job of transcribing an audio track with a single monophonic instrument (an instrument that produces only one pitch at a given time such as flute or vocals) when the amount of noise on the track is low. Transcription of single polyphonic instruments (an instrument that can produce more than one pitch at a time such as piano or guitar) from low-noise audio recordings is also fairly well developed.
Other transcription problems are more challenging. Transcribing single track recording containing an ensemble of instruments is difficult since the audio mix must be separated into individual instrument components. The various instruments often produce pitches and harmonics that overlap at a given point in time. Percussion instruments in the mix can overpower all the other instruments at instants near beats. Crowd noise in live recordings, static and distortion in old recordings, or equipment hum can cause problems for transcription systems. Instruments that can produce a given pitch in more than one way are difficult if the transcription is to include the specific method for producing the pitches (such as tablature for string instruments).
This last problem is our current research focus. Specifically, we are investigating automatic transcription of tablature for steel-string acoustic guitars. In this research we attempt to determine not only which pitches are to be played at each point in time, but also which string/fret combinations produce each of these pitches. We hope to address other transcription challenges at a future date.
One mechanism to further this research is via a Vertically Integrated Project administered by Boise State University's College of Innovation and Design. These projects attempt to bring undergraduate students into real research projects for course credit as early as the Freshman year to work with others up to the doctoral level. The VIPs are intended to be ongoing projects with new students added and others graduating every year.