Earphone active noise control
A method of active noise reduction. The method comprises instructing a microphone electronically coupled by a client terminal to record a nonaural noise signal, instructing a circuit of the client terminal to record an aural noise signal using at least one electroacoustic transducer of an earphone, calculating a noise reduction signal based on a function combining nonaural noise signal and the aural noise signal, calculating a noise reduced signal based on a combination of a content signal prepared to be played by the at least one electroacoustic transducer and the noise reduction signal, and instructing the circuit to play the noise reduced signal via the at least one electroacoustic transducer. The nonaural noise signal and the aural noise signal are recorded at least partly simultaneously.
1. A method for performing active noise reduction, comprising:
recording, by a computing system, a first noise signal with a microphone;
recording, by the computing system, a second noise signal with an electroacoustic transducer;
calculating, by the computing system, a noise reduction signal based on calculations that combine the first noise signal and the second noise signal, by taking into account:
(i) a portion of the second noise signal recorded with the electroacoustic transducer,
(ii) a constant vector of the electroacoustic transducer when recording the second noise signal, and
(iii) an echo vector for the electroacoustic transducer when recording the second noise signal;
generating, by the computing system, a noise reduced signal based on a combination of a content signal prepared to be played and the noise reduction signal; and
playing, by the computing system, the noise reduced signal using the electroacoustic transducer,
wherein the first noise signal and the second noise signal are recorded at least partly simultaneously.
2. The method of claim 1 , wherein the constant vector of the electroacoustic transducer represents a transformation between a signal sent to the electroacoustic transducer and a signal played by the electroacoustic transducer.
3. The method of claim 2 , wherein the transformation between the signal sent to the electroacoustic transducer and the signal played by the electroacoustic transducer is determined during a calibration process.
4. The method of claim 1 , wherein calculating the noise reduction signal comprises estimating a current noise at location of the electroacoustic transducer according to a phase difference between the first noise signal and the second noise signal.
5. The method of claim 4 , wherein calculating the noise reduction signal comprises calculating a noise prediction signal based on said current noise and then calculating a sound wave with a same amplitude but with an inverted phase of the noise prediction signal.
6. The method of claim 1 , wherein said noise reduced signal includes said noise reduction signal and said content signal as different channels which are set to be played simultaneously.
7. The method of claim 1 , wherein said noise reduced signal is a mix of said noise reduction signal and said content signal.
8. The method of claim 1 , wherein recording the second noise signal includes recording the second noise signal in a space between the electroacoustic transducer and an ear of a user.
9. The method of claim 1 , wherein:
recording the first noise signal includes recording the first noise signal at least 10 centimeters from a user ear; and
recording the second noise signal includes recording the second noise signal less than 3 centimeters from the user ear.
10. A client terminal having noise reducing functionality, comprising:
a housing;
an earphone interface to connect to an earphone that includes an electroacoustic transducer;
a computerized processor;
a microphone; and
computer readable medium comprising computer executable instructions adapted to perform the following operations upon execution by the computerized processor:
record a first noise signal with the microphone;
record a second noise signal with the electroacoustic transducer;
calculate a noise reduction signal based on calculations that combine the first noise signal and the second noise signal, by taking into account:
(i) a portion of the second noise signal recorded with the electroacoustic transducer,
(ii) a constant vector of the electroacoustic transducer when recording the second noise signal, and
(iii) an echo vector for the electroacoustic transducer when recording the second noise signal;
generate a noise reduced signal based on a combination of a content signal prepared to be played and the noise reduction signal; and
play the noise reduced signal using the electroacoustic transducer,
wherein the first noise signal and the second noise signal are recorded at least partly simultaneously.
11. The client terminal of claim 10 , wherein the constant vector of the electroacoustic transducer represents a transformation between a signal sent to the electroacoustic transducer and a signal played by the electroacoustic transducer.
12. The client terminal of claim 11 , wherein the transformation between the signal sent to the electroacoustic transducer and the signal played by the electroacoustic transducer is determined during a calibration process.
13. The client terminal of claim 10 , wherein calculating the noise reduction signal comprises estimating a current noise at location of the electroacoustic transducer according to a phase difference between the first noise signal and the second noise signal.
14. The client terminal of claim 13 , wherein calculating the noise reduction signal comprises calculating a noise prediction signal based on said current noise and then calculating a sound wave with a same amplitude but with an inverted phase of the noise prediction signal.
15. The client terminal of claim 10 , wherein said noise reduced signal includes said noise reduction signal and said content signal as different channels which are set to be played simultaneously.
16. The client terminal of claim 10 , wherein said noise reduced signal is a mix of said noise reduction signal and said content signal.
17. The client terminal of claim 10 , wherein recording the second noise signal includes recording the second noise signal in a space between the electroacoustic transducer and an ear of a user.
18. The client terminal of claim 10 , wherein:
recording the first noise signal includes recording the first noise signal at least 10 centimeters from a user ear; and
recording the second noise signal includes recording the second noise signal less than 3 centimeters from the user ear.
19. A client terminal having noise reducing functionality, comprising:
a housing;
an earphone interface to connect to an earphone device that includes an electroacoustic transducer and a microphone;
a computerized processor; and
computer readable medium comprising computer executable instructions adapted to perform the following operations upon execution by the computerized processor:
record a first noise signal with the microphone;
record a second noise signal with the electroacoustic transducer;
calculate a noise reduction signal based on calculations that combine the first noise signal and the second noise signal, by taking into account:
(i) a portion of the second noise signal recorded with the electroacoustic transducer,
(ii) a constant vector of the electroacoustic transducer when recording the second noise signal, and
(iii) an echo vector for the electroacoustic transducer when recording the second noise signal;
generate a noise reduced signal based on a combination of a content signal prepared to be played and the noise reduction signal; and
play the noise reduced signal using the electroacoustic transducer,
wherein the first noise signal and the second noise signal are recorded at least partly simultaneously.