Automatic transcription of musical content and real-time musical accompaniment

1. A method for generating an accompaniment for musical content included in a first audio signal, the method comprising:

receiving the first audio signal via an audio input device;

extracting, from the first audio signal, musical information characterizing at least a portion of the musical content;

generating a second audio signal that has at least one of a rhythmic relationship and a harmonic relationship with the musical information; and

transmitting, substantially immediately after receiving the first audio signal, the second audio signal to an audio output device;

wherein receiving the first audio signal and extracting the musical information are associated with a learning mode, and generating a second audio signal and transmitting the second audio signal are associated with an accompaniment mode; and

wherein, during both the learning mode and the accompaniment mode, the musical information is extracted from the first audio signal substantially continuously.

2. The method of claim 1 , wherein receiving the first audio signal comprises receiving a musical phrase associated with the musical content, and transmitting the second audio signal comprises transmitting, substantially immediately after receiving the musical phrase, the second audio signal to the audio output device.

3. The method of claim 1 , further comprising:

generating a third audio signal that is more complex than the second audio signal and has at least one of a rhythmic relationship and a harmonic relationship with the musical information;

halting transmission of the second audio signal to the audio output device; and

transmitting, substantially immediately after halting transmission of the second audio signal, the third audio signal to the audio output device.

4. The method of claim 1 , further comprising updating musical information corresponding to a portion of the first audio signal received in a most recent period of time having a predetermined length.

5. The method of claim 1 , wherein the first audio signal includes musical content associated with a first type of musical instrument, and the second audio signal includes second musical content associated with a second type of musical instrument.

6. The method of claim 5 , wherein the first type of musical instrument comprises a first stringed instrument, and the second type of musical instrument comprises at least one of a second stringed instrument and a percussive instrument.

7. A non-transitory computer-readable storage medium including instructions that, when executed by a processor, configure the processor to generate accompaniment for musical content included in a received audio signal by performing the steps of:

receiving a first audio signal via an audio input device;

receiving an indication that the first audio signal has been received;

extracting, from the first audio signal, musical information characterizing at least a portion of the musical content;

generating a second audio signal that has at least one of a rhythmic relationship and a harmonic relationship with the musical information; and

transmitting, substantially immediately after receiving the indication, the second audio signal to an audio output device,

wherein receiving the first audio signal and extracting the musical information are associated with a learning mode, and generating a second audio signal and transmitting the second audio signal are associated with an accompaniment mode; and

wherein, during both the learning mode and the accompaniment mode, the musical information is extracted from the first audio signal substantially continuously.

8. The non-transitory computer-readable storage medium of claim 7 , wherein the second audio signal is transmitted no more than 40 milliseconds after receiving the indication.

9. The non-transitory computer-readable storage medium of claim 7 , wherein the second audio signal is transmitted no more than one beat of a musical meter associated with the musical information after receiving the indication.

10. A musical accompaniment device configured to generate accompaniment for musical content included in a received audio signal, the device comprising:

an audio input device;

an audio output device;

a memory; and

a processor that is coupled to the memory and the processor being configured to:

receive a first audio signal via an audio input device; and

extract, from the first audio signal, musical information characterizing at least a portion of the musical content;

receive a musical characteristic associated with the musical information;

generate, based on the musical characteristic, a second audio signal that has at least one of a rhythmic relationship and a harmonic relationship with the musical information; and

transmit, substantially immediately after receiving the first audio signal, the second audio signal to an audio output device,

wherein the processor is further configured to receive the first audio signal and to extract the musical information in a learning mode, and wherein the processor is further configured to generate the second audio signal and to transmit the second audio signal in an accompaniment mode, and

wherein, during both the learning mode and the accompaniment mode, the musical information is extracted from the first audio signal substantially continuously.

11. The musical accompaniment device of claim 10 , wherein the processor is further configured to receive an indication to transition from the learning mode to the accompaniment mode.

12. The musical accompaniment device of claim 11 , wherein the indication comprises at least one of a selection of a user interface (UI) element and closing a switch.

13. The musical accompaniment device of claim 10 , wherein the processor is further configured to update musical information corresponding to a portion of the audio signal received in a most recent period of time having a predetermined length.

14. The musical accompaniment device of claim 10 , wherein the second audio signal includes at least a portion of the first audio signal.

15. The musical accompaniment device of claim 10 , wherein the processor is further configured to:

generate, based on the musical characteristic, a third audio signal that has at least one of a rhythmic relationship and a harmonic relationship with the musical information and includes additional information relative to the second audio signal; and

subsequent to transmitting the second audio signal, transmit the third audio signal to an audio output device.

16. The musical accompaniment device of claim 10 , wherein the musical characteristic comprises at least one of a key signature, a chord, a note pitch, a number of measures or bars, a time signature, a tempo, and a rhythm.