If you’re moving enough air with the exhaust fan located outside of the tent it’s fine there. What you have to understand about the noise is that some is coming from the fan itself, and some is coming from the air movement. If the majority of noise you’re hearing is from the fan, you can build an insulated box around it and knock it down quite a bit.
The air movement is a little more difficult to silence. It usually requires muffler type devices that also restrict airflow. Can be done though if you’re creative enough.
There’s also the potential that your speed controller isn’t compatible with your fan, which can create some noise. That’s usually more of a whining type of noise though, that you typically don’t hear at full speed.