Canon D20 - Manual (Page 71)

Image Customization Features
71
Distorted audio caused by recording when the wind is strong can be reduced.
However, the recording may sound unnatural when this option is used when
there is no wind.
Configure the setting.
Press the n button, choose [Wind Filter]
on the 4 tab, and then choose [On] (p. 42).
To restore the original setting, repeat this
process but choose [Off].
Using the Wind Filter
Movies