Installatøren sier at det kommer an på om vibrasjonsstøyen er lav.

It means it depends on.

This is a very common Norwegian expression:

• Det kommer an på været. = It depends on the weather.
• Det kommer an på om han har tid. = It depends on whether he has time.

Literally, the parts are:

• det = it
• kommer = comes
• an på = a fixed particle + preposition combination

But you should learn det kommer an på as a whole expression, not word by word.

Because at introduces a subordinate clause and means that.

So:

• Installatøren sier = The installer says
• at det kommer an på ... = that it depends on ...

In English, that is often optional:

• The installer says (that) it depends on...

In Norwegian, at is very commonly used in this kind of sentence.

Here, om means whether.

So:

• om vibrasjonsstøyen er lav = whether the vibration noise is low

This is a very common use of om after verbs or expressions involving uncertainty, doubt, or dependence:

• Jeg vet ikke om han kommer. = I don’t know whether he is coming.
• Det kommer an på om det regner. = It depends on whether it rains.

A learner often notices that om can also mean about, but that is a different use.

Because after om, you normally get subordinate clause word order.

In a subordinate clause, Norwegian usually keeps the subject before the verb:

• vibrasjonsstøyen er lav

Compare:

• Main clause question: Er vibrasjonsstøyen lav? = Is the vibration noise low?
• Subordinate clause: ... om vibrasjonsstøyen er lav = ... whether the vibration noise is low

So even though the English translation may feel question-like because of whether, Norwegian does not use question word order here.

It is a compound noun:

• vibrasjon = vibration
• støy = noise
• vibrasjonsstøy = vibration noise

Then the ending -en makes it definite singular:

• vibrasjonsstøy = vibration noise
• vibrasjonsstøyen = the vibration noise

The -s- in the middle is a common linking element in Norwegian compounds:

• vibrasjon + støy → vibrasjonsstøy

Because it is the definite singular form:

• en installatør = an installer
• installatøren = the installer

So the sentence is talking about a specific installer, not just any installer.

This definite ending is very common in Norwegian:

• en bil → bilen
• en lærer → læreren
• en installatør → installatøren

Yes. Lav means low, and it can be used about level, amount, or intensity, including sound/noise.

So vibrasjonsstøyen er lav means the vibration noise is at a low level.

Depending on context, English might translate this more naturally as:

• the vibration noise is low
• the vibration noise level is low
• the vibration noise is quiet

But in Norwegian, lav is completely normal here.

In this expression, det is a formal or dummy subject. It does not point to one specific noun in the sentence.

This is similar to English expressions like:

• It depends
• It is raining
• It seems strange

So in det kommer an på, the det is just part of the standard structure. You generally cannot leave it out.

Yes. All the verbs are present tense:

• sier = says
• kommer = comes / depends
• er = is

So the sentence describes a present statement:

• The installer says that it depends on whether the vibration noise is low.

Norwegian present tense is often quite simple in form, and it is used in many of the same situations as English present tense.

Yes. A common alternative is avhenger av, which also means depends on.

For example:

• Installatøren sier at det avhenger av om vibrasjonsstøyen er lav.

That is understandable, but det kommer an på is often especially common in everyday speech.

A rough comparison:

• det kommer an på = very common, natural, conversational
• avhenger av = also common, sometimes a bit more formal or abstract depending on context

Sometimes English uses if where Norwegian uses om, but in this sentence whether is the best explanation.

English often says:

• It depends on if the vibration noise is low
• It depends on whether the vibration noise is low

Many English speakers say if in everyday speech, but whether is more precise here. Norwegian uses om for this idea.

So for learners, it is safest to think:

• om after det kommer an på = whether

Yes, sometimes they can, because an is a particle and på belongs with the expression. In simple sentences, though, it is easiest to learn the basic pattern:

• Det kommer an på + noun
• Det kommer an på + om-clause

Examples:

• Det kommer an på prisen. = It depends on the price.
• Det kommer an på om han svarer. = It depends on whether he answers.

In more advanced sentences, Norwegian word order may separate parts of phrasal expressions, but at your stage it is best to memorize the standard chunk det kommer an på.