Sensed Sound Level Based Fan Speed Adjustment

Abstract

Sounds sensed by a microphone of a device include sounds from a cooling fan of the device that varies based on the speed of the cooling fan, and other sounds used by a program of the device such as voice inputs. The sound level of sounds used by the program is determined, and the speed of the fan is adjusted so that a desired cooling level is attained while keeping the fan speed low enough that the noise from the fan does not interfere with the sounds used by the program.

What is claimed is: 
     
         1 . A method implemented in a device, the method comprising:
 detecting a sound level of sounds sensed by a microphone, the sounds including a particular range of frequencies used by a program of the device, and the program receiving audio inputs in the particular range of frequencies via the microphone;   determining a sound level of a fan of the device at a current fan speed; and   adjusting a speed of the fan so that the sound level of the fan is less than a sound level sensed by the microphone that is attributable to sounds other than fan noise, the adjusting further comprising reducing how quickly the speed of the fan is adjusted in response to changes in sound level of the fan by averaging the current fan speed over an amount of time.   
     
     
         2 . A method as recited in  claim 1 , the adjusting further comprising adjusting the speed of the fan to run at at least a threshold speed to provide a desired amount of cooling regardless of the sound level of the fan. 
     
     
         3 . A method as recited in  claim 1 , the program comprising a program to record voices at the device, the particular range of frequencies comprising frequencies that are recorded by the program. 
     
     
         4 . A method as recited in  claim 1 , the program comprising a video conferencing program that transmits voices to an additional device, the particular range of frequencies comprising frequencies that are transmitted to the additional device. 
     
     
         5 . A method as recited in  claim 1 , further comprising playing back, via one or more speakers of the device, a sound wave that cancels at least part of the sound level of the fan. 
     
     
         6 . A method as recited in  claim 1 , the determining comprising using a speed to noise transfer function to identify the sound level generated by the fan of the device at the current fan speed. 
     
     
         7 . A method as recited in  claim 6 , the speed to noise transfer function being determined for only the particular range of frequencies used by the program. 
     
     
         8 . A method as recited in  claim 1 , the microphone comprising one of multiple microphones of the device that is sensing a highest sound level, lowest sound level, or averaged sound level of the multiple microphones. 
     
     
         9 . A method as recited in  claim 1 , the averaging comprising averaging all received speed indications over an amount of time. 
     
     
         10 . A method as recited in  claim 1 , the averaging comprising performing a weighted averaging of speed indications over an amount of time. 
     
     
         11 . A method as recited in  claim 1 , wherein the amount of time over which received speed indications are averaged is a value configured by a user or administrator. 
     
     
         12 . A system in a device, the system comprising:
 a microphone that detects sounds in a particular range of frequencies used by a program of the device;   a fan motor that controls, based on an input voltage, a speed of a fan of the device;   a difference logic coupled to receive audio data including the sounds sensed by the microphone in the particular range of frequencies, the difference logic being configured to determine, based on both a sound level of the sounds sensed by the microphone and a sound level generated by the fan of the device at a current fan speed, a voltage to apply to the fan motor so that a sound level of the fan is less than a sound level sensed by the microphone of sounds other than fan noise; and   a filter configured to reduce how quickly the voltage to apply to the fan motor is adjusted in response to changes in the sound level of the fan by averaging an indication of the sound level of the fan over an amount of time.   
     
     
         13 . A system as recited in  claim 12 , the system further including a threshold cooling voltage to apply to the fan motor so that the speed of the fan provides a desired amount of cooling regardless of the voltage determined by the difference logic. 
     
     
         14 . A system as recited in  claim 12 , the system further comprising a speed to noise transfer function that identifies the sound level of the fan at various speeds, the sound level of the fan of the device at the current fan speed being identified by the speed to noise transfer function. 
     
     
         15 . A system as recited in  claim 14 , the speed to noise transfer function being determined for only the particular range of frequencies used by the program. 
     
     
         16 . A system as recited in  claim 12 , further comprising one or more speakers configured to play back a sound wave that cancels or reduces the sound generated by the fan. 
     
     
         17 . A method implemented in one or more computing devices, the method comprising:
 detecting a sound level of sounds sensed by a microphone, the sounds including a particular range of frequencies;   determining a sound level of a fan of the device at a current fan speed; and   adjusting a speed of the fan so that the sound level of the fan is less than a sound level sensed by the microphone that is attributable to sounds other than fan noise, the adjusting further comprising reducing how quickly the speed of the fan is adjusted in response to changes in sound level of the fan by at least averaging a value of a control signal indicating a voltage to apply to a motor of the fan over an amount of time.   
     
     
         18 . The method as recited in  claim 17 , the adjusting further comprising adjusting the speed of the fan to run at at least a threshold speed to provide a desired amount of cooling regardless of the sound level of the fan. 
     
     
         19 . The method as recited in  claim 17 , further comprising playing back, via one or more speakers of the device, a sound wave that cancels at least part of the sound level of the fan. 
     
     
         20 . The method as recited in  claim 17 , further comprising:
 determining a second sound level of a second fan of the one or more computing devices at a second current fan speed; and   adjusting a speed of the second fan so that he sound level of both of the fans is less than the sound level sensed by the microphone that is attributable to sounds other than fan noise.