Method and apparatus for canceling fan noise in a computer system
View Patent ↗One embodiment of the present invention provides a system that cancels fan noise in a computer system. During operation, the system obtains a fan noise signal using a microphone. Next, the system generates a spectral pattern based on the obtained fan noise signal. The system then uses the spectral pattern to identify a corresponding cancellation spectrum in an anti-spectra library. Next, the system generates a noise-canceling signal using the cancellation spectrum. Note that the amount of computation required to cancel fan noise is reduced because generating the noise-canceling signal using the anti-spectra library requires less computation than generating the noise-canceling signal using dynamic noise-cancellation techniques.
1. A method for canceling fan noise in a computer system, the method comprising:
obtaining a fan noise signal using a microphone;
generating a spectral pattern based on the obtained fan noise signal;
identifying a cancellation spectrum in an anti-spectra library using the spectral pattern, wherein the anti-spectra library includes at least one cancellation spectrum computed based on a fan noise signal that includes a combination of multiple fan speeds; and
generating a noise-canceling signal using the cancellation spectrum;
wherein the amount of computation required to cancel fan noise is reduced because generating the noise-canceling signal using the anti-spectra library requires less computation than dynamically generating the noise-canceling signal.
2. The method of claim 1 , further comprising:
computing cancellation spectra based on fan noise signals measured at various fan speeds; and
storing the cancellation spectra in the anti-spectra library.
3. The method of claim 1 , wherein identifying the cancellation spectrum involves:
determining a fan speed based on the spectral pattern; and
identifying the cancellation spectrum based on the fan speed.
4. The method of claim 1 , wherein generating the noise canceling signal involves playing back the noise canceling signal on a speaker.
5. The method of claim 1 , further comprising:
detecting one or more fan failures; and
stopping noise-cancellation if one or more fan failures are detected, wherein stopping noise-cancellation can prevent suboptimal noise-cancellation because, if one or more fans fail, the spectral pattern can be substantially different from the cancellation spectrum which is associated with a system configuration in which all fans are operational.
6. The method of claim 5 , wherein detecting one or more fan failures involves:
determining a thermal distribution using thermal sensors, wherein an anomalous thermal distribution can indicate a fan failure; and
determining whether a fan speed is below a normal operating speed using a Hall-effect RPM (revolution per minute) sensor.
7. The method of claim 6 , wherein the thermal distribution can be used to validate the output of the Hall-effect RPM sensor, thereby improving fan operability assurance.
8. A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for canceling fan noise in a computer system, the method comprising:
obtaining a fan noise signal using a microphone;
generating a spectral pattern based on the obtained fan noise signal;
identifying a cancellation spectrum in an anti-spectra library using the spectral pattern, wherein the anti-spectra library includes at least one cancellation spectrum computed based on a fan noise signal that includes a combination of multiple fan speeds; and
generating a noise-canceling signal using the cancellation spectrum;
wherein the amount of computation required to cancel fan noise is reduced because generating the noise-canceling signal using the anti-spectra library requires less computation than dynamically generating the noise-canceling signal.
9. The computer-readable storage medium of claim 8 , wherein the method further comprises:
computing cancellation spectra based on fan noise signals measured at various fan speeds; and
storing the cancellation spectra in the anti-spectra library.
10. The computer-readable storage medium of claim 8 , wherein identifying the cancellation spectrum involves:
determining a fan speed based on the spectral pattern; and
identifying the cancellation spectrum based on the fan speed.
11. The computer-readable storage medium of claim 8 , wherein generating the noise canceling signal involves playing back the noise canceling signal on a speaker.
12. The computer-readable storage medium of claim 8 , wherein the method further comprises:
detecting one or more fan failures; and
stopping noise-cancellation if one or more fan failures are detected, wherein stopping noise-cancellation can prevent suboptimal noise-cancellation because, if one or more fans fail, the spectral pattern can be substantially different from the cancellation spectrum which is associated with a system configuration in which all fans are operational.
13. The computer-readable storage medium of claim 12 , wherein detecting one or more fan failures involves:
determining a thermal distribution using thermal sensors, wherein an anomalous thermal distribution can indicate a fan failure; and
determining whether a fan speed is below a normal operating speed using a Hall-effect RPM (revolution per minute) sensor.
14. The computer-readable storage medium of claim 13 , wherein the thermal distribution can be used to validate the output of the Hall-effect RPM sensor, thereby improving fan operability assurance.
15. An apparatus for canceling fan noise in a computer system, comprising:
a microphone, which is configured to obtain a fan noise signal;
a spectral-pattern-generating mechanism configured to generate a spectral pattern based on the obtained fan noise signal;
an identifying mechanism configured to identify a cancellation spectrum in an anti-spectra library using the spectral pattern, wherein the anti-spectra library includes at least one cancellation spectrum computed based on a fan noise signal that includes a combination of multiple fan speeds; and
a signal-generating mechanism configured to generate a noise-canceling signal using the cancellation spectrum;
wherein the amount of computation required to cancel fan noise is reduced because generating the noise-canceling signal using the anti-spectra library requires less computation than dynamically generating the noise-canceling signal.
16. The apparatus of claim 15 , further comprising:
a computing mechanism configured to compute cancellation spectra based on fan noise signals measured at various fan speeds; and
a storing mechanism configured to store the cancellation spectra in the anti-spectra library.
17. The apparatus of claim 15 , wherein the identifying mechanism is configured to:
determine a fan speed based on the spectral pattern; and to
identify the cancellation spectrum based on the fan speed.
18. The apparatus of claim 15 , wherein the signal-generating mechanism is configured to play back the noise canceling signal on a speaker.
19. The apparatus of claim 15 , wherein the apparatus is configured to:
detect one or more fan failures; and to
stop noise-cancellation if one or more fan failures are detected, wherein stopping noise-cancellation can prevent suboptimal noise-cancellation because, if one or more fans fail, the spectral pattern can be substantially different from the cancellation spectrum which is associated with a system configuration in which all fans are operational.
20. The apparatus of claim 19 , wherein detecting one or more fan failures involves:
determining a thermal distribution using thermal sensors, wherein an anomalous thermal distribution can indicate a fan failure; and
determining whether a fan speed is below a normal operating speed using a Hall-effect RPM (revolution per minute) sensor.
21. The apparatus of claim 20 , wherein the thermal distribution can be used to validate the output of the Hall-effect RPM sensor, thereby improving fan operability assurance.