Wind noise reduction by microphone placement

1. An image capture device, comprising:

a housing having a top housing surface, a front housing surface, and two side housing surfaces;

a lens snout protruding from the front housing surface;

a front microphone mounted within the housing behind the front housing surface and below the lens snout;

a top microphone mounted within the housing under the top housing surface;

a drainage microphone mounted within the housing behind one of the side housing surfaces, wherein the drainage microphone is positioned less than 30 degrees from the front microphone relative to a horizontal axis of the housing; and

an audio processor comprising a memory that is configured to store instructions that when executed cause the audio processor to generate an output audio signal,

wherein the top microphone is located at a position under the top housing surface to receive direct freestream air flow when the housing is positioned in a pitched forward orientation at a first pitched forward angle relative to a vertical axis, and

wherein the front microphone is located at a position under the front housing surface to receive turbulent air flow from the lens snout when the housing is positioned in the pitched forward orientation at a second pitched forward angle relative to the vertical axis.

2. The image capture device of claim 1 , wherein the second pitched forward angle is greater than or equal to the first pitched forward angle.

3. The image capture device of claim 1 , wherein the front microphone is positioned below the lens snout.

4. The image capture device of claim 1 , wherein the top microphone is biased within the housing under the top housing surface towards the front housing surface.

5. The image capture device of claim 1 ,

wherein the audio processor is configured to execute the instructions stored in the memory so that when the instructions are executed, the audio processor is configured to:

receive a first audio signal from the front microphone;

for frequency sub-bands, generate first frequency sub-band signals from the first audio signal;

receive a second audio signal from the top microphone;

for the frequency sub-bands, generate second frequency sub-band signals from the second audio signal;

receive a third audio signal from the drainage microphone;

for the frequency sub-bands, generate third frequency sub-band signals from the third audio signal;

for the respective frequency sub-bands, select one of the first frequency sub-band signals, the second frequency sub-band signals, or the third frequency sub-band signals having the lowest noise metric; and

combine the selected sub-band signals to generate the output audio signal.

6. The image capture device of claim 1 , wherein when the drainage microphone includes a channel entrance surface area to channel volume ratio that moves audio wave resonance outside of a 500 Hz to 9 kHz frequency range.

7. The image capture device of claim 1 , wherein the memory stores instructions that when executed cause the audio processor to:

perform beamforming on the first frequency sub-band signals and the third frequency sub-band signals to output a stereo audio stream.

8. An image capture device, comprising:

a housing having a first housing surface, a second housing surface orthogonal to the first housing surface, and a third housing surface orthogonal to the first housing surface and the second housing surface;

a protruding feature protruding from the first housing surface;

a first microphone mounted within the housing behind the first housing surface and adjacent to the protruding feature;

a second microphone mounted within the housing under the second housing surface;

a third microphone mounted within the housing behind the third housing surface, wherein the third microphone comprises a drainage microphone that is positioned on a side housing surface of the housing and is biased towards a second housing surface of the housing at an angle of less than 30 degrees from the second microphone relative to a horizontal axis of the housing; and

an audio processor comprising a memory configured to store instructions that when executed cause the audio processor to generate an output audio signal,

wherein the first microphone is located at a position under the first housing surface to receive direct freestream air flow when the housing is positioned in a pitched orientation with a first pitched angle; and

wherein the second microphone is located at a position under the second housing surface to receive turbulent air flow from the protruding feature when the housing is positioned in the pitched orientation with a second pitched angle.

9. The image capture device of claim 8 , wherein the second pitched angle is greater than or equal to the first pitched angle.

10. The image capture device of claim 8 , wherein the second microphone is positioned below the protruding feature.

11. The image capture device of claim 8 , wherein when the first microphone is biased within the housing under the first housing surface towards the second housing surface.

12. The image capture device of claim 8 ,

wherein the memory stores instructions that when executed cause the audio processor to:

receive a third audio signal from the third microphone;

for the frequency sub-bands, generate third frequency sub-band signals from the third audio signal;

for the respective frequency sub-bands, select one of the first frequency sub-band signals, the second frequency sub-band signals, or the third frequency sub-band signals having the lowest noise metric; and

combine the selected sub-band signals to generate the output audio signal.

13. The image capture device of claim 8 , wherein the memory stores instructions that when executed cause the audio processor to perform beamforming on the first frequency sub-band signals and the third frequency sub-band signals to output a stereo audio stream.

14. A method of reducing wind noise in an image capture device, comprising:

receiving, by an audio processor, a first audio signal from a first microphone mounted above a protruding feature extending from a first housing surface of a housing of an image capture device, the first microphone mounted to receive direct freestream air flow when the housing is positioned in a pitched forward orientation at a first pitched forward angle;

receiving, by the audio processor, a second audio signal from a second microphone mounted below the protruding feature, the second microphone mounted to receive turbulent air flow when the housing is positioned in the pitched forward orientation at a second pitched forward angle, the second pitched forward angle being greater than or equal to the first pitched forward angle;

receiving, by the audio processor, a third audio signal from a third microphone that is a drainage microphone mounted within the housing behind one of the side housing surfaces and is positioned less than 30 degrees from the second microphone relative to a horizontal axis of the housing;

generating, by the audio processor, for frequency sub-bands, first frequency sub-band signals from the first audio signal;

generating, by the audio processor, for the frequency sub-bands, second frequency sub-band signals from the second audio signal;

generating, by the audio processor, for the frequency sub-bands, third frequency sub-band signals from the third audio signal;

selecting, by the audio processor, for respective frequency sub-bands, one of the first frequency sub-band signals, the second frequency sub-band signals, or the third sub-band signals having a lowest noise metric; and

combining, by the audio processor, the selected sub-band signals to generate an output audio signal.

15. The method of claim 14 , wherein the first microphone and the second microphone are positioned on separate orthogonal surfaces of the housing.

16. The method of claim 14 , wherein the second microphone is positioned on the same surface of the housing as the protruding feature.

17. The image capture device of claim 1 , wherein the drainage microphone includes a channel volume depth that is not uniform and varies from an upper channel volume depth to a lower channel volume depth.

18. The image capture device of claim 8 , wherein the drainage microphone includes a channel volume depth that is not uniform and varies from an upper channel volume depth to a lower channel volume depth.

19. The method of claim 14 , wherein when the drainage microphone includes a channel entrance surface area to channel volume ratio that moves audio wave resonance outside of a 500 Hz to 9 kHz frequency range.

20. The method of claim 14 , wherein the audio processor comprises memory and the method further comprises a step of storing instructions in the memory that when executed cause the audio processor to:

perform beamforming on the first frequency sub-band signals and the third frequency sub-band signals to output a stereo audio stream.