Stemmegruppen velger konsertantrekket.

Because Norwegian very often forms compound nouns as one word, where English would often use two or more words.

• stemmegruppe = stemme
  • gruppe
• konsertantrekk = konsert
  • antrekk

When these are made definite, they become:

• stemmegruppen = the voice group / the vocal section
• konsertantrekket = the concert outfit

Writing them as separate words would usually be wrong in standard Norwegian.

Those endings mark the definite form of the noun, roughly like English the.

• en stemmegruppe = a voice group

• stemmegruppen = the voice group

• et konsertantrekk = a concert outfit
• konsertantrekket = the concert outfit

So instead of using a separate word like English the, Norwegian often adds the definiteness directly to the noun.

Because the two nouns have different grammatical genders.

• stemmegruppe is a common-gender noun, so the indefinite article is en, and the definite ending is usually -en.
• antrekk is a neuter noun, so the indefinite article is et, and the definite ending is usually -et.

That is why you get:

• en stemmegruppe → stemmegruppen
• et antrekk → antrekket

Velger is the present tense of å velge (to choose).

A useful thing for English speakers is that Norwegian verbs do not change according to person:

• jeg velger = I choose / am choosing
• du velger = you choose / are choosing
• han/hun velger = he/she chooses
• vi velger = we choose
• de velger = they choose

So velger stays the same regardless of who the subject is.

Yes. This is the basic subject–verb–object order:

• Stemmegruppen = subject
• velger = verb
• konsertantrekket = object

So the structure is very similar to English:

• The vocal section chooses the concert outfit.

This makes the sentence fairly straightforward for an English speaker.

In a musical or choir context, stemmegruppe usually means a voice section, such as:

• sopranos
• altos
• tenors
• basses

So it is not just any random group. It usually refers to the singers belonging to one particular vocal part.

It can cover both, depending on context.

So velger can mean:

• chooses
• is choosing

Norwegian usually does not make the same strong distinction that English does between simple present and present continuous. Context tells you which is meant.

It would be:

En stemmegruppe velger et konsertantrekk.

That means something like A vocal section chooses a concert outfit.

Compare:

• Stemmegruppen velger konsertantrekket. = the specific group chooses the specific outfit
• En stemmegruppe velger et konsertantrekk. = a group chooses an outfit

Because Norwegian often expresses definiteness by attaching it to the noun itself.

Instead of saying:

• the group
• the outfit

Norwegian commonly says:

• gruppen
• antrekket

This is one of the most important differences from English noun structure.

Yes, but that would usually add extra emphasis or specification.

For example:

• den stemmegruppen = that / that particular voice group
• det konsertantrekket = that / that particular concert outfit

In your sentence, plain stemmegruppen and konsertantrekket are enough because the nouns are simply definite, not especially emphasized.

The spelling keeps the g, but in speech the pronunciation can be less obvious than an English speaker might expect. In standard Norwegian, velge is pronounced roughly like VEL-ye or VEL-ge depending on dialect and phonetic detail, not with a hard English g sound as in go.

This is normal in Norwegian: spelling and pronunciation do not always match English expectations exactly, especially around combinations like lg.

Yes. Norwegian makes compounds very freely, and this is a very typical pattern:

• first noun describes the type or purpose
• second noun is the main noun

So in konsertantrekk:

• konsert tells you what kind of outfit it is
• antrekk is the main noun

The whole word means an outfit used for concerts or performance settings.

The dictionary forms are:

• stemmegruppe for stemmegruppen
• antrekk for konsertantrekket if you are looking up the head noun, or konsertantrekk as the full compound
• å velge for velger

This is useful because Norwegian dictionaries usually list nouns in the indefinite singular form and verbs in the infinitive.

Sometimes, yes, depending on context. Velger basically means chooses / selects, but in natural English a sentence like this might sometimes be phrased as:

• The vocal section decides on the concert outfit.

That is more about natural English style than Norwegian grammar. The Norwegian verb itself is still simply velger.