Sound, we can see because of radars and how they affect things, such as a sonic boom. Spoken language has letters, which are written down. Proof. But time?
We can only see sound because of tools, we cannot see it directly. We can see time through a clock, a tool, even if we can't see it directly. If language is written down, then it is no longer spoken.
Spoken language can be heard, too. That leaves it in history. Sound can be "seen" directly using tools. Clocks move on an arranged pattern. We can see the "clocks" tick and tock, but not "time".