The dwemer had Tonal Architects (and they were scientists/magecrafters/philosophers?)

But why exactly are they called Tonal Architects? I read that Tonal has something to do with the spiritual link between a person and an animal (like a totem or something)
But that's our world. Is it the same in TES, or what exactly does it mean to be a Tonal Architect?

It means you drum the Heart to reproduce the scream of Lorkhan, by secret murder, which inaugurated Creation. The Tonal Architects were assigned to design a ritual for tapping into the Heart of Lorkhan, and they came up with forenoted theory to echo Creation and change the present.

Because manipulating the heart was just like playing music. Hit the heart with Sunder, and it makes all sorts of sounds. With Keening, it is refined to the desired pitch, volume, and frequency.

They also used tones in things like locks. Septimus Signus mentions hearing them from the giant lockbox.

The guy was also off his rocker.

That's a good point. Maybe he just imagined it because he thought the Heart of Lorkhan was inside.

Storyteller.

Just to clarify for the OP: It's "Tonal" as in "tones". Sound, music, story.

Ah, that's what I first thought. I got confused by my google search

The sermons suggest that tonal architecture isn't strictly limited to doom-drumming. Solid sounds as cutting implements and so forth.

They were quite profient at torturing the Heart of a God, and manipulated it's screams into desired effects!

Bindbending - not to mention evil!
Makes the things they did to the Falmer look cheap!