Low latency active noise cancellation system
View Patent ↗Systems and methods described herein provide for low latency active noise cancellation, which alleviates the problems associated with analog filter circuitry. The present technology utilizes low latency digital signal processing techniques that overcome the high latency conventionally associated with conversion between the analog and digital domains. As a result, low latency active noise cancellation is performed utilizing digital filter circuitry which is not subject to the inaccuracies and drift of analog filter components. In doing so, the present technology provides robust, high quality active noise cancellation.
1. A method for reducing an acoustic energy level at a listening position, the method comprising:
receiving a primary acoustic wave at a reference position to form an analog reference signal;
converting the analog reference signal into a single-bit digital reference signal using an oversampling data converter;
transforming the single-bit digital reference signal into a multi-bit PCM data stream;
filtering the multi-bit PCM data stream to form a digital noise reduction signal;
producing an analog noise reduction signal using the digital noise reduction signal; and
generating a secondary acoustic wave based on the analog noise reduction signal, the secondary acoustic wave adapted to reduce the acoustic energy level at the listening position.
2. The method of claim 1 , wherein the digital noise reduction signal is a multi-bit digital noise reduction signal.
3. The method of claim 1 , wherein the oversampling data converter is a sigma-delta modulator.
4. The method of claim 1 , wherein a latency between receiving the primary acoustic wave and generating the secondary acoustic wave is less than or equal to 10 microseconds.
5. The method of claim 1 , wherein the primary acoustic wave is received at the reference position by a reference microphone arranged on an earpiece of a headset, and the secondary acoustic wave is generated by an audio transducer arranged on the earpiece.
6. The method of claim 5 , further comprising:
receiving the primary acoustic wave and the secondary acoustic wave via a monitoring microphone to form a monitoring signal, the monitoring microphone arranged between the audio transducer and the listening position; and
generating the secondary acoustic wave further based on the monitoring signal.
7. The method of claim 1 , further comprising:
receiving a digital desired signal; and
producing the analog noise reduction signal further using the digital desired signal.
8. A system for reducing an acoustic energy level at a listening position, the system comprising:
a reference microphone configured to receive a primary acoustic wave at the listening position;
a noise cancellation module configured to:
convert an analog reference signal into a single-bit digital reference signal using an oversampling data converter;
transform the single-bit digital reference signal into a multi-bit PCM data stream;
filter the multi-bit PCM data stream to form a digital noise reduction signal;
produce an analog noise reduction signal using the digital noise reduction signal; and
an audio transducer to generate a secondary acoustic wave based on the analog noise reduction signal, the secondary acoustic wave adapted to reduce the acoustic energy level at the listening position.
9. The system of claim 8 , wherein the digital noise reduction signal is a multi-bit digital noise reduction signal.
10. The system of claim 8 , wherein the oversampling data converter is a sigma-delta modulator.
11. The system of claim 8 , wherein a latency between receiving the primary acoustic wave and generating the secondary acoustic wave is less than or equal to 10 microseconds.
12. The system of claim 8 , wherein the reference microphone and the audio transducer are each arranged on an earpiece of a headset.
13. The system of claim 12 , further comprising:
a monitoring microphone to receive the primary acoustic wave and the secondary acoustic wave to form a monitoring signal, the monitoring microphone arranged between the audio transducer and the listening position, wherein the noise cancellation module forms the digital noise reduction signal further based on the monitoring signal.
14. The system of claim 8 , wherein the noise cancellation module is further configured to:
receive a digital desired signal; and
produce the analog noise reduction signal further using the digital desired signal.
15. A non-transitory computer readable storage medium having embodied thereon a program, the program being executable by a processor to perform a method for reducing an acoustic energy level at a listening position, the method comprising:
receiving a primary acoustic wave at a reference position to form an analog reference signal;
converting the analog reference signal into a single-bit digital reference signal using an oversampling data converter;
transforming the single-bit digital reference signal into a multi-bit PCM data stream;
filtering the multi-bit PCM data stream to form a digital noise reduction signal;
producing an analog noise reduction signal using the digital noise reduction signal; and
generating a secondary acoustic wave based on the analog noise reduction signal, the secondary acoustic wave adapted to reduce the acoustic energy level at the listening position.
16. The non-transitory computer readable storage medium of claim 15 , wherein the digital noise reduction signal is a multi-bit digital noise reduction signal.
17. The non-transitory computer readable storage medium of claim 15 , wherein the method further comprises:
receiving a digital desired signal; and
producing the analog noise reduction signal further using the digital desired signal.