# US 8,541,676 B1 · Method for extracting individual instrumental parts from an audio recording and optionally outputting sheet music

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- Number: US 8,541,676 B1
- Document ID: US8541676B1
- Status: Granted
- Kind: B1
- Application number: 13/042,172
- Filed: 2011-03-07
- Granted: 2013-09-24
- Earliest claimed: 2010-03-06
- Applicants: Alexander Waldman
- Inventors: Alexander Waldman
- Web page: https://patentgrep.com/patent/US8541676B1

## CPC

- G10H 1/0008: {Associated control or indicating means}
- G10H 2210/056: for extraction or identification of individual instrumental parts, e.g. melody, chords, bass; Identification or separation of instrumental parts by their characteristic voices or timbres
- G10H 2220/015: Musical staff, tablature or score displays, e.g. for score reading during a performance
- G10H 2240/131: Library retrieval, i.e. searching a database or selecting a specific musical piece, segment, pattern, rule or parameter set
- G10H: ELECTROPHONIC MUSICAL INSTRUMENTS; INSTRUMENTS IN WHICH THE TONES ARE GENERATED BY ELECTROMECHANICAL MEANS OR ELECTRONIC GENERATORS, OR IN WHICH THE TONES ARE SYNTHESISED FROM A DATA STORE

## Abstract

A method and computer based program which performs a series of steps for automatically and accurately determining each note played in a song for each instrument and vocal. The method and program can transcribe or create sheet music for each individual instrument, as well as provide the ability to remove any combination of or individual instruments or vocal track basically from nearly any existing song, or future songs.

## Claims

### Claim 1

A computer based method for extracting individual instrumental parts from an audio recording, said method comprising the steps of:
a. providing an audio recording;
b. selecting a sample rate;
c. calculating through a computer a cross-spectral density between the audio recording and a soft attack sample over a time domain of the soft attack sample at n=1, wherein n=1 representing a first sample of the audio recording;
d. calculating through a computer an autospectral density of the audio recording over the time domain of the soft attack sample in step (c);
e. calculating through a computer a coherence between the audio recording and the soft attack sample over the domain of the soft attack sample at n−1 using the calculations from step (c) and step (d) and information for the soft attack sample stored in an electronic database;
f. recording the calculated value for coherence;
g. repeating steps (c) through (e) at a beginning of each new sample of the audio recording from n=2 until a (n−x)th sample, where x is a number of samples in the domain of the soft attack sample and n is a total number of samples for the audio recording based on the sample rate selected in step (b);
h. repeating steps (c) through (g) for medium attack samples and for loud attack samples;
i. repeating steps (c) through (h) for each note for each instrument selected;
j. identifying through a computer peaks of coherence values between the attack samples and the audio recording for each note of each instrument; and
k. recording the note, force, instrument and timecode data at which each peak occurs in the electronic database or another electronic database.

### Claim 2 (depends on 1)

The computer based method for extracting individual instrumental parts from an audio recording of claim 1, wherein step (i) comprises repeating until all sample in the electronic database have been compared to the audio recording and all samples for all instruments selected have been compared to the audio recording.

### Claim 3 (depends on 1)

The computer based method for extracting individual instrumental parts from an audio recording of claim 1 wherein step (j) comprises the step of comparing by a computer only coherence values which were calculated using the same note and instrument.

### Claim 4 (depends on 1)

The computer based method for extracting individual instrumental parts from an audio recording of claim 1 wherein step (k) comprises only recording peaks that are above a pre-specified level.

### Claim 5 (depends on 1)

The computer based method for extracting individual instrumental parts from an audio recording of claim 1 further comprising the steps of:
l. beginning at each peak, calculating through a computer a coherence between a corresponding sustain sample (same note, force and instrument as the peak's attack sample) and the audio recording over the time domain of the attack sample;
m. calculating through the computer a coherence between a corresponding sustain sample and the audio recording beginning at a next sample;
n. repeating steps (l) and (m) until the coherence falls below a pre-determined value;
o. recording a duration of each note (which is an ending timecode of a last sample above an acceptable coherence value subtracted from a beginning timecode of a first sample) in the electronic database or another electronic database; and
p. repeating steps (l) through (o) for each note for each instrument selected until steps (I) through (o) have been performed for all peaks.

### Claim 6 (depends on 5)

The computer based method for identifying individual instrumental parts from an audio recording of claim 5 further comprising the step (q) of resynthesizing all instrumental parts and/or voice from the audio recording, only particular instrumental parts and/or voice, or all instrumental parts and/or voice except one or two in particular.

### Claim 7 (depends on 6)

The computer based method for identifying individual instrumental parts from an audio recording of claim 6 wherein step (q) comprises the steps of:
q1. resynthesizing the audio recording by the computer using the note/force/instrument/duration data and physical modeling synthesis to yield a resynthesized audio file; and
q2. subtracting the resynthesized audio file from the audio recording by the computer to yield a vocal part.

### Claim 8 (depends on 7)

The computer based method for identifying individual instrumental parts from an audio recording of claim 7 wherein step (q) further comprises the step (q3) of copying the vocal part to its own audio file.

### Claim 9 (depends on 7)

The computer based method for identifying individual instrumental parts from an audio recording of claim 7 wherein step (q) further comprises the step (q3) of adding the vocal part to the resynthesized audio file to generate a final audio file containing only the instruments and voice parts selected.

### Claim 10 (depends on 7)

The computer based method for identifying individual instrumental parts from an audio recording of claim 7 further comprising the step (r) creating sheet music by the computer for one or more of the instrumental or vocal parts of the audio recording.

### Claim 11 (depends on 10)

The computer based method for identifying individual instrumental parts from an audio recording of claim 10 wherein step (r) comprises the steps of
r1. for each instrumental of the audio recording selected for sheet music converting data generated in steps (j), (k), (o) and (p) into music notation; and
r2. printing or displaying sheet music containing the music notation from step r1.

### Claim 12 (depends on 10)

The computer based method for identifying individual instrumental parts from an audio recording of claim 10 wherein step (r) comprises the steps of
r1. for each vocal part of the audio recording selected for sheet music, performing a FFT (Cooley-Tukey algorithm) on the audio file for the vocal part previously derived;
r2. assigning note values by the computer to corresponding dominant frequencies for a duration of the frequency;
r3. using the data from step (r2) to generate sheet music; and
r4. printing or displaying sheet music for the vocal part.