System and method for automatically detecting a set of fundamental frequencies simultaneously present in an audio signal

DETAILED DESCRIPTION OF THE INVENTION With reference to the drawings, FIGS.
1-22 depict the preferred embodiment of the wave file to MIDI file converter of the instant invention, which is generally referenced by numeric character 1000.
The instant invention comprises a recognizer program 4000 which recognizes which notes make up the audio signal received from audio source 1 and may also include or interface with an analog-to-digital ("A/D") converter 2, a wave file recorder 3, a wave file 5, a MIDI file 6, a transcriber 7, sheet music 8, a sequencer 9, a MIDI interface 10, a synthesizer 11, and/or an audio output 12.
The invention is to the recognizer 4000 alone, but may also comprise an entire system such as 1000.
The recognizer 4000 determines the notes from an analog input signal, having a plurality of frequencies simultaneously present, by reverse engineering or decomposing the wave form.
As music comprises a combination of sound or sine waves added together, the input signal comprises an aggregate or complex wave form.
Consequently, the period of the aggregate wave form is always changing which makes it impossible to find the frequency.
Additionally, the period is the combination of wavelengths of the component frequencies.
The period itself does not indicate the frequencies present.
With reference to FIG.
19, the instant invention 4000 solves this problem by breaking up the aggregate wave form into segments based on time or any other suitable basis which are referenced as sample windows.
In each sample window, a plurality of sine waves in digital form are each individually subtracted from the corresponding portion of the aggregate/complex wave form to arrive at a correlation score.
The lower the score, the better, whereby zero represents an ideal score.
By subtracting out individual notes or frequencies from the aggregate wave form in the window, the invention 4000 is able to determine which notes or frequencies comprise the wave file, i.
e.
, the aggregate wave form.
As these notes or frequencies comprise sine waves, the instant invention includes a sine wave table from which notes are selected for subtracting from the wave file to arrive at a correlation score