В комнате было слишком шумно, чтобы спокойно говорить с оператором.

Because this is an impersonal sentence.

The core idea is not the room was noisy in the usual subject-predicate sense. Instead, Russian is saying something more like:

In the room, it was too noisy...

In these impersonal sentences, Russian often uses:

• a state word like шумно, холодно, темно, трудно
• plus было in the past tense

So:

• В комнате шумно = It is noisy in the room.
• В комнате было шумно = It was noisy in the room.

The form было is neuter singular past, which is the standard form often used in impersonal constructions.

Here, шумно is best understood as a predicative adverb or word of state.

It looks like an adverb, and in many grammar explanations it is grouped with words that describe a general condition or environment:

• тихо = quiet
• холодно = cold
• темно = dark
• жарко = hot
• шумно = noisy

In this sentence, шумно does not describe a noun directly. It describes the situation/environment.

So this is different from:

• шумная комната = a noisy room

Here we do not have шумная because Russian is not describing комната as a noun; it is describing the overall condition in the room.

Because в plus the prepositional case is used to mean in when talking about location.

• комната = room
• в комнате = in the room

So:

• в комнате answers where?

This is standard:

• в доме = in the house
• в машине = in the car
• в школе = at school / in the school

If it were motion into the room, Russian would usually use the accusative instead:

• в комнату = into the room

But here there is no movement; it is simply the location of the noise.

This is a very common pattern meaning:

too ... to ...

So:

• слишком шумно = too noisy
• чтобы спокойно говорить = to speak calmly

Together:

слишком шумно, чтобы спокойно говорить
= too noisy to speak calmly

More examples:

• Слишком поздно, чтобы звонить.
  = Too late to call.

• Он слишком устал, чтобы работать.
  = He is too tired to work.

A useful thing to remember is that чтобы here introduces the result/limit after too.

Because чтобы introduces a subordinate clause, and Russian normally separates that clause with a comma.

So:

• В комнате было слишком шумно, чтобы спокойно говорить с оператором.

That comma is standard and expected.

You will see the same with similar structures:

• Он был слишком занят, чтобы прийти.
• Слишком темно, чтобы читать.

Because спокойно modifies the verb говорить, so Russian uses an adverb, not an adjective.

• спокойный = calm (adjective, describes a noun)
• спокойно = calmly / in a calm way (adverb, describes an action)

Here the idea is:

to speak calmly

So Russian says:

• спокойно говорить

Compare:

• спокойный человек = a calm person
• человек говорит спокойно = the person speaks calmly

Говорить is the natural choice here because the sentence is about the process of speaking/conversing, not one completed utterance.

A few contrasts:

• говорить = to speak, to talk
• сказать = to say, to tell, to utter something specific
• поговорить = to have a talk, to talk for a while

In a noisy environment, the problem is the ongoing act of communication, so говорить fits well.

Also, after слишком ... чтобы ..., Russian often uses the infinitive in a broad, general sense:

• слишком холодно, чтобы гулять
• слишком рано, чтобы вставать
• слишком шумно, чтобы говорить

Because the verb говорить с кем? requires с + instrumental when it means to speak with someone.

• оператор = operator
• с оператором = with an operator

So the pattern is:

• говорить с другом = speak with a friend
• говорить с учителем = speak with the teacher
• говорить с оператором = speak with the operator

This is a standard government pattern of the verb and preposition.

Literally, it means with the operator. In natural English, depending on context, that may be translated as:

• speak with the operator
• talk to the operator

Russian uses с because it focuses on communication with a person.

So even if English might prefer to in some contexts, Russian still says:

• говорить с кем-то

Yes, there is no explicit subject, and that is normal.

The structure is roughly:

• В комнате = location
• было = was
• слишком шумно = too noisy
• чтобы спокойно говорить с оператором = to speak calmly with the operator

Russian often builds sentences around a state rather than around a named subject. English often inserts a dummy subject like it:

• It was too noisy in the room to speak calmly with the operator.

Russian does not need that kind of placeholder subject here.

Yes. Russian word order is flexible, although the original version sounds very natural.

Original:

• В комнате было слишком шумно, чтобы спокойно говорить с оператором.

Other possible orders include:

• Было слишком шумно в комнате, чтобы спокойно говорить с оператором.
• С оператором было слишком шумно говорить в комнате.
  This is grammatically possible, but it changes the emphasis and sounds less neutral.

The original puts В комнате first, which naturally sets the scene: in the room.

In many modern contexts, оператор often means a telephone/call-center operator or customer service representative.

So the sentence likely suggests something like:

• it was too noisy in the room to talk calmly to a support operator
• it was too noisy to speak with the person handling the call

However, оператор can also mean other kinds of operator depending on context, such as a machine operator or camera operator. The exact meaning depends on the situation.

Yes. A very useful pattern is:

[Location / situation] + было / будет / было бы + слишком + state/adjective + чтобы + infinitive

Examples:

• Здесь слишком темно, чтобы читать.
  = It is too dark here to read.

• На улице было слишком холодно, чтобы долго гулять.
  = It was too cold outside to walk for long.

• Он слишком устал, чтобы работать.
  = He is too tired to work.

Your sentence follows exactly that pattern:

• В комнате было слишком шумно, чтобы спокойно говорить с оператором.