Enumerates the types of capture settings describing an audio
file.
Values:
MICROPHONE_DISTANCE_UNSPECIFIED (0):
Audio type is not known.
NEARFIELD (1):
The audio was captured from a closely placed
microphone. Eg. phone, dictaphone, or handheld
microphone. Generally if there speaker is within
1 meter of the microphone.
MIDFIELD (2):
The speaker if within 3 meters of the
microphone.
FARFIELD (3):
The speaker is more than 3 meters away from
the microphone.