This is a common phenomenon in English, where the pronunciation of certain letters can be affected by the letters around them. In this case, the "t" is followed by "s" and "r", which creates a sound that is difficult to articulate.
Here's why it happens:
* Phonetic rules: The combination of "ts" followed by "r" often results in a silent "t" in English. This is similar to how the "t" is silent in words like "castle," "listen," and "often."
* Historical evolution: The word "debris" originally came from the French word "débris," where the "t" was pronounced. Over time, as the word was adopted into English, the pronunciation shifted to make it sound more like other English words.
So, even though the "t" isn't pronounced, it's still part of the spelling and affects the pronunciation of the surrounding sounds.