Sharc Information
SHARC ("Sandell Harmonic Archive") is a public-domain, World Wide Web-available research database of musical timbre. It consists of steady state spectra taken from over 1300 different musical instrument tones, including complete chromatic runs from the standard playing range of the primary non-percussive instruments of the modern orchestra (39 instruments total). For example, individual analyses of 32 different oboe notes (the chromatic scale from the pitches a#3 to f6) are available. The source of the musical notes were the orchestral tones from the McGill University Master Samples (MUMS) Compact Discs, digital recordings of live musical performers. For each note, a short portion corresponding to the sustain or "steady state" portion of the tone was selected and analysed with a Fourier analysis. Detail on the selection and analysis process will be presented. Each analysis consists of a list of amplitudes and phases for all the note's harmonics in the range 0-10,000 Hz.
The database is available on the World Wide Web (http://www.parmly.luc.edu/sharc). Users can download the entire database or "browse" it using SHARC's interactive plotting and soundfile features. A user can request a plot of any individual note for a given instrument, and explore ways of plotting it using various amplitude and frequency scales, or choosing between linear spectra and excitation patterns. Similarly, a soundfile may be synthesized from the spectrum of any note and be played on the user's Web browser (e.g. NetScape). For comparison, several of the original recordings are on-line as well to consider the veracity of the steady state presentations.
SHARC is limited to steady state spectra because the amount of space required for full time-variant representations of the 1300 notes in this collection would exceed 25 gigabytes, a disk requirement that is still impractical for most researchers. While transients and other time-varying detail are critical components for the perception of timbre, the steady-state nonetheless carries a large propotion of the information of a tone. The balance struck in this collection between economy of representation (steady state spectra) and completeness (complete chromatic scales for each instrument) offers opportunity for timbral discovery. Specifically, it puts the study of the "macro timbre" of an instrument, i.e. its spectral content of its entire pitch range, within the grasp of the researcher.
Some of the uses to which SHARC has been put are:
- Calculating the spectral centroids of the notes.
- Estimating "roughness" or acoustic consonance of notes.
- Studying level (dynamics) differences between instruments.
- Investigating questions of orchestration by combining spectra into simulated harmonies.
- A composer may wish to search the database to find the most acoustically consonant orchestration for a particular chord.
- Or a theorist might construct simulated orchestrations of scores for music analysis.
- Test proposition about the makeup of acoustical "signatures" of musical instruments. For example, the often made claim that the oboe and English horn possess "formants" can be tested.