This will be a brief, but detailed guide on how to lower the adds on our servers.
Step 1. Open up the Volume Mixer by right clicking your volume control, and selecting Open Volume Mixer.
Step 2. Scroll over the Volume Mixer until you find Steam Client WebHelper. This is the volume control for both the Steam overlay and the advertisements.
Step 3. Simply lower the volume to whatever fits your needs, whether it be a volume of 10 or 1.
Keep in mind that this will also affect the volume of your Steam overlay, so making the advertisements inaudible will make any websites opened in the overlay inaudible as well.