Learn Hardcore Turkish: Çamaşır makinesi çalışırken ben de salonda kitap okuyorum. - While the washing machine is running, I read a book in the living room.

çalış- + ıyor + ken → çalışırken (the vowel in -ıyor drops: çalışıyorken → çalışırken).
So the whole phrase çamaşır makinesi çalışırken = “while the washing machine is running”.

Why is it çamaşır makinesi and not just çamaşır makine?

Turkish often uses a noun + noun (possessive) compound to make new nouns:

çamaşır = laundry
makine = machine
çamaşır makinesi = laundry machine → washing machine

The second noun gets a 3rd‑person possessive ending (-si) to show this compound relationship:
çamaşır makine + si → çamaşır makinesi.
This is a fixed expression; you normally say çamaşır makinesi for “washing machine”.

What does ben de mean here, and how is that different from bende?

In this sentence, ben de means “I also / I too”.

ben = I
de (separate word) = also / too

So ben de salonda kitap okuyorum = “I’m also reading a book in the living room.”

This is different from bende (one word), which is ben + -de (locative suffix) and means “on me / at me / with me”, e.g. Para bende. = “The money is with me.”

What is the role of de in ben de? Could I leave it out?

De here is a focus particle meaning “also / too / as well”.

With de: Ben de salonda kitap okuyorum. = “I also am reading a book in the living room.”
Without de: Ben salonda kitap okuyorum. = “I am reading a book in the living room.” (no “also / too” nuance)

Grammatically you can leave it out, but you lose the idea that you are doing something in addition to someone/something else (here: in addition to the washing machine working).

Why is it salonda and not something like salon içinde for “in the living room”?

Turkish usually expresses “in/at/on” by using a case ending instead of a separate preposition:

salon = living room
-da / -de = locative case = in / at / on

So salonda literally means “in the living room”.
You can sometimes see salonun içinde (“inside the living room”) for emphasis, but salonda is the normal, simple way.

Why is the subject ben stated? Could the sentence be Çamaşır makinesi çalışırken salonda kitap okuyorum?

Yes, you can omit ben:

Çamaşır makinesi çalışırken ben de salonda kitap okuyorum.
Çamaşır makinesi çalışırken salonda kitap okuyorum.

Both are grammatical.
Turkish verb endings already show the subject (okuyor-um = “I am reading”), so pronouns like ben are optional and usually added for emphasis or contrast. With ben de, you stress that I, too am doing something.

What tense is okuyorum, and why is it used here?

Okuyorum is the present continuous tense:

oku- = read
-yor = continuous aspect
-um = 1st person singular (“I”)

So okuyorum = “I am reading.”
It matches the idea of an action happening right now, at the same time as the washing machine is running.

Why does çalışırken look like a different tense from okuyorum? Are they in different tenses?

They look different, but they are related.

çalışırken is based on the present continuous (çalışıyor) + -ken (“while/when”), which then contracts to çalışırken.
okuyorum is a normal present continuous form.

So semantically, both are present continuous, but çalışırken is turned into a “while doing X” subordinate clause. That’s why one has -ken and the other has the regular -yorum ending.

Is the word order fixed? Could I say Ben de salonda, çamaşır makinesi çalışırken, kitap okuyorum?

The word order is flexible in Turkish. All of these are possible:

Çamaşır makinesi çalışırken ben de salonda kitap okuyorum.
Ben de salonda çamaşır makinesi çalışırken kitap okuyorum.
Ben de salonda, çamaşır makinesi çalışırken, kitap okuyorum.

The default, natural order in Turkish tends to place the “while…” clause first and the main verb at the end, as in the original sentence. Moving phrases changes emphasis and rhythm, but not the basic meaning.

Why is there no word for “while” like in English? Where is “while” in the Turkish sentence?

The idea of “while” is expressed by the suffix -ken, not by a separate word.

çalışırken = “while (it is) working / running”

So the English “while” is “hidden” inside çalışırken.
Turkish often uses such verb + suffix combinations instead of separate conjunction words.

Does de/da change spelling according to vowel harmony, like -de/-da on nouns?

No—this is an important distinction:

-de / -da attached to a word is the locative case suffix (in/at/on) and it obeys vowel harmony: evde, okulda, etc.
de / da written as a separate word is the “also/too” particle and does not obey vowel harmony. It is always de or da based only on consonant voicing rules, and in modern spelling it’s almost always written as de unless it follows a word ending in an unvoiced consonant (then da).

In ben de, de is the separate “also” particle, not the locative suffix.

How would the meaning change if I said Çamaşır makinesi çalışıyor, ben de salonda kitap okuyorum instead of çalışırken?

Çamaşır makinesi çalışırken ben de salonda kitap okuyorum.
= “While the washing machine is running, I’m also reading a book in the living room.” (explicit simultaneity)
Çamaşır makinesi çalışıyor, ben de salonda kitap okuyorum.
= “The washing machine is running; I’m also reading a book in the living room.”

The second sentence still implies that the actions are simultaneous, but çalışırken makes the “while/at the same time” relationship more explicit and tighter.