Consonant harmony!

Something interesting I came across follows. First, some context.

David and Asuman Pollard's wonderful textbook Teach Yourself Turkish shows how Turkish handles to, at, and from as follows:

• -de indicates there's no movement to or from
• -e indicates there's movement towards
• -den indicates there's movement away from

The example provided is simple:

English	Turkish
house	ev
at the house	evde
to the house	eve
from the house	evden

Now, here's the interesting part (or what I call a curveball): a d can become a t! The Pollards explain it as follows:

Question: What do the words maç, dolap, beş, sokak, and raf have in common? Answer: They all end in a 'whispery' (unvoiced) consonant. The d in the ending becomes t in order to be whispery too. This is similar to vowel harmony, but with consonants!

Consonant harmony!? Very cool. Çok serin.

Apart from that interesting and logical twist, it also helps me feel less bewildered when I see words that don't show up in Turkish dictionaries and which I can't parse with the other rules I've learned so far.

Again, very cool. Tekrar, çok serin.