All sounding is a type of urethral, yes, but not all urethral activities are sounding. Sounding involves specific tools penetrating the urethra, most usually thin metal rods.
Therefore, as things currently stand... If someone wants to look at SPECIFICALLY sounding, they'll have to sort through everything tagged with urethral. Which includes urethral_fucking, urethral_fisting, cock_vore, etcetera.
To allow people to find specifically Sounding, its alias to Urethral should be changed to an implication.
Putting this here as a fresh thread because the alias has no forum post.
Updated by user 59725