Разве мы не должны идти к аварийному выходу, если слышна сирена?

Разве adds a sense of surprise, doubt, or mild contradiction. It often suggests that the speaker thought the answer was obvious or expected.

In this sentence, разве makes it feel like:

• Isn't it the case that... ?
• Aren't we supposed to... ?
• Wait, shouldn't we... ?

So it is not just a neutral question. It sounds like the speaker is reacting to something, maybe because people are not going to the emergency exit when the siren sounds.

In Russian, yes/no questions do not always need special word order. Very often, a sentence becomes a question mainly through:

• intonation
• question particles like разве, неужели, ли

So Разве мы не должны идти к аварийному выходу...? is clearly a question because of разве and the overall intonation.

Russian does not need English-style inversion like Shouldn't we go...?

In this sentence, it means aren’t we supposed to go / shouldn’t we go.

That is an important point, because English shouldn’t can mean two different things:

• It would be wrong to go
• Aren’t we expected to go?

Here, because of разве and the context, the meaning is the second one: the speaker thinks going to the emergency exit is probably the correct procedure.

Without context, не должны can sometimes be ambiguous, but here the intended meaning is clearly about obligation/expectation.

Идти is the imperfective verb, and пойти is perfective.

Here идти works well because the sentence is about the general action/process of going in response to a situation:

• должны идти = should be going / should go

It focuses on what people are supposed to do, not on a single completed result.

If you said пойти, that would emphasize starting the action or a more one-time movement:

• Разве мы не должны пойти к аварийному выходу...?

That is also possible, but it feels a bit more like Shouldn’t we go head over there now?

So идти is very natural when talking about procedure or expected behavior.

Because к means toward / to in the sense of moving in the direction of something.

• идти к выходу = go to/toward the exit

You are moving toward the exit, not into it.

Using в would usually suggest movement into some enclosed space, which does not fit well with exit here.

So:

• идти к аварийному выходу = go to the emergency exit

This is the normal Russian way to say it.

Because the preposition к requires the dative case.

So both words change to dative singular:

• аварийный → аварийному
• выход → выходу

That gives:

• к аварийному выходу

This is a very common pattern in Russian:

• к дому
• к машине
• к большому зданию

So the form is not special to this phrase; it is just normal dative after к.

Слышна сирена means something like the siren is audible / a siren can be heard.

This structure is different from мы слышим сирену:

• мы слышим сирену = we hear the siren
• слышна сирена = the siren is heard / audible

Russian often uses this kind of impersonal-feeling or descriptive construction when the important point is that the sound is present, not who hears it.

So если слышна сирена is very natural for signs, rules, instructions, and formal statements.

Because сирена is a feminine singular noun, and слышна agrees with it.

Compare:

• слышен звук — masculine
• слышна сирена — feminine
• слышно пение — neuter-like/adverbial-style usage
• слышны голоса — plural

So слышна matches сирена grammatically.

Yes. It is the short form of the adjective слышный, and in modern Russian it often functions like audible or can be heard.

Short-form adjectives are commonly used as part of the predicate:

• дверь открыта = the door is open
• он готов = he is ready
• сирена слышна = the siren is audible

In this sentence, слышна is the predicate, and сирена is the subject.

Because in present-tense Russian, to be is usually omitted.

So where English says:

• The siren is audible

Russian simply says:

• Сирена слышна

The same thing happens in many other sentences:

• Он дома = He is at home
• Она готова = She is ready
• Вы правы = You are right

So the missing is is completely normal.

Because если слышна сирена is a subordinate clause.

Russian normally puts a comma before если when it introduces an if-clause:

• Мы уйдём, если будет поздно.
• Позвони, если сможешь.
• Разве мы не должны идти к аварийному выходу, если слышна сирена?

This comma rule is very regular.

That would be much less natural here.

Слышна сирена is the standard, elegant way to say the siren is audible.

Слышно сирену can occur in colloquial speech, but it is less neutral and less standard in a sentence like this. For a learner, если слышна сирена is the better model.

They are close, but not always exactly the same.

• аварийный выход = emergency exit
• запасной выход = secondary / alternate / spare exit

In many real-life situations, people may use them similarly, especially on signs, but аварийный выход more directly emphasizes use in an emergency.

So in your sentence, аварийный выход is a very logical choice.

Yes:

• Разве нам не нужно идти к аварийному выходу, если слышна сирена?

This is also natural. The difference is mainly one of tone:

• должны = stronger sense of duty, rule, or obligation
• нужно = necessary / need to

So должны can sound a bit more like isn’t that what we are required to do?, while нужно can sound more like isn’t that what we need to do?

Both are correct, but должны fits very well if the speaker is referring to a rule or procedure.