How do you silent the air sound through ducting?

[Budgrower]

I have an inline fan venting to my garage , only problem is the air sound through the venting? How can you dampen the sound?

 

[ChicagoJoe]

I have an inline fan venting to my garage , only problem is the air sound through the venting? How can you dampen the sound?

insulated ductwork

 

[Weed420]

homedepot and lowes sell a duct muffler or you could copy them and build one yourself.