Vibrasjonsstøyen er lav.

Because Norwegian normally writes compound nouns as one word.

Here, vibrasjonsstøyen is built from:

• vibrasjon = vibration
• støy = noise
• -en = the definite ending

So the core compound is vibrasjonsstøy = vibration noise, and then -en makes it the vibration noise.

English often uses separate words for this kind of expression, but Norwegian usually combines them into one noun.

That -s- is a linking element used in many Norwegian compounds.

So:

• vibrasjon
  • støy
    becomes
• vibrasjonsstøy

This -s- does not usually add meaning by itself. It mainly helps the compound sound natural and follow common word-building patterns.

You cannot always predict perfectly when Norwegian will use a linking -s-, so this is something learners gradually get used to by seeing more compounds.

The ending -en marks the noun as definite: the.

So:

• vibrasjonsstøy = vibration noise
• vibrasjonsstøyen = the vibration noise

In Norwegian, the definite article is often added to the end of the noun instead of being a separate word like English the.

Because Norwegian usually expresses definiteness by adding an ending to the noun.

For many masculine nouns in Bokmål:

• en bil = a car
• bilen = the car

Here, støyen works the same way inside the compound:

• vibrasjonsstøyen = the vibration noise

So English uses a separate word (the), but Norwegian often uses a suffix.

The adjective agrees with the noun.

Here, the head noun is støy, which is usually treated as a masculine noun in Bokmål, so the adjective in this predicate position is:

• lav

Compare:

• Støyen er lav. = The noise is low.
• Nivået er lavt. = The level is low.
  (nivå is neuter, so the adjective becomes lavt.)
• Kostnadene er lave. = The costs are low.
  (plural gives lave)

So lav is the correct form because the noun here is singular and not neuter.

Er is the present tense of å være = to be.

So:

• er = is / are

In this sentence, er links the subject and the adjective:

• Vibrasjonsstøyen er lav.
• The vibration noise is low.

This is the normal way to make a simple present-tense statement with to be.

It is an adjective.

More specifically, it is a predicative adjective, because it comes after er and describes the subject:

• Vibrasjonsstøyen = the vibration noise
• er lav = is low

This is different from an adjective directly before a noun, such as:

• lav støy = low noise

So in your sentence, lav is still an adjective, but it is not placed directly before the noun.

Yes. This is the standard word order for a simple statement:

• Subject + verb + complement
• Vibrasjonsstøyen + er + lav

This is very similar to English:

• The vibration noise + is + low

Norwegian is a verb-second language, but in a basic main clause where the subject comes first, the result often looks quite similar to English.

It depends on what you mean, but in many contexts that sounds less natural.

• Vibrasjonsstøyen er lav = the vibration noise is low
  This refers to a specific noise, or the noise in a particular machine/system/context.

• Vibrasjonsstøy er lav would sound more like a general statement about vibration noise as a concept, and that is often less natural unless the context clearly calls for a generic statement.

In technical writing, the definite form is very common when talking about a specific measured or discussed feature.

A learner will often notice three things:

• the compound is long, so it has a main stress earlier in the word
• sj/støy has the Norwegian sh-like sound in støy
• øy is a vowel combination that many English speakers find difficult

A rough guide is:

• vi-bra-SJONS-støy-en

The øy sound has no exact English equivalent. It is something you usually need to hear and imitate.

Also, compounds in Norwegian are pronounced as one unit, not as separate words.

Yes, especially in a technical or formal context.

It sounds like something you might see in:

• product specifications
• engineering reports
• machine descriptions
• test results

In everyday conversation, people might use simpler wording depending on context, but the sentence itself is perfectly normal Norwegian.

The main noun is støy.

In Norwegian compounds, the last element is usually the main word, and the earlier part modifies it.

So:

• vibrasjons- tells you what kind of noise
• støy is the core noun: noise

This is why the whole word refers to a type of noise, not a type of vibration.

The indefinite version would be:

• Vibrasjonsstøy er lav. or, depending on context, a more natural rephrasing might be used.

But if you want a clear singular indefinite noun phrase, Norwegian often prefers either:

• a different structure, or
• a noun that works more naturally with an article

The definite version Vibrasjonsstøyen er lav is often the most natural in technical contexts because it refers to a specific known noise source or measured quantity.

So as a learner, the main contrast to notice is:

• vibrasjonsstøy = vibration noise
• vibrasjonsstøyen = the vibration noise