Det er den musik, min datter lytter til, når hun tegner på sit værelse.

Det er is a very common Danish way to identify or point something out.

Here, det does not mean a specific thing by itself; it works like the it/that in English sentences such as:

• It is the music ...
• That is the music ...

So Det er den musik ... is a natural identifying structure in Danish. Starting directly with Den musik ... would usually require a different sentence pattern.

This is a very common learner question.

In Danish, when a noun is defined by something that comes after it, such as a relative clause, you often use:

• den/det/de + noun in base form

So:

• den musik, min datter lytter til

rather than:

• musikken, min datter lytter til

The following clause min datter lytter til is what identifies which music we mean, so Danish normally uses den musik here.

A useful comparison:

• musikken = the music in a more standalone sense
• den musik, ... = the music that ...

Danish often leaves out the relative word when it is not the subject of the clause.

So all of these are possible in principle:

• den musik, som min datter lytter til
• den musik, min datter lytter til

In this sentence, the omitted word would be som. Leaving it out is very normal and natural.

So the full structure is basically:

• den musik, (som) min datter lytter til

Because lytte normally goes with the preposition til:

• lytte til musik = listen to music

In the relative clause, the object of til is the noun musik, which has already appeared earlier:

• den musik ...
• min datter lytter til

So the preposition is left behind at the end. This is called preposition stranding, and it is very common in Danish.

English does the same thing:

• the music my daughter listens to

You could think of the full relationship as:

• min datter lytter til den musik

but den musik has been moved to the front as the thing being described.

Because lytte usually does not take a direct object by itself in this meaning. Danish uses the fixed pattern:

• lytte til noget = listen to something

So you say:

• Hun lytter til musik
• not normally Hun lytter musik

This is just a verb pattern you have to learn as a unit: lytte til.

Når is used for something that happens whenever, when, or as in a repeated or general situation.

Here the idea is that this is the music she listens to when she is drawing — in other words, during that kind of situation, not just one single past event.

Use da for a specific event in the past:

• Da hun tegnede i går, lyttede hun til musik.
  = When she was drawing yesterday, she listened to music.

Use når for habitual or general meaning:

• Når hun tegner, lytter hun til musik.
  = When she draws / Whenever she draws, she listens to music.

Because når hun tegner ... is a subordinate clause.

In main clauses, Danish normally follows the V2 rule, where the verb is in second position. But after a subordinating word like når, that main-clause inversion does not happen.

So you get normal subordinate-clause order:

• når hun tegner
• fordi hun tegner
• hvis hun tegner

Not:

• når tegner hun

That inverted order belongs to main clauses, for example:

• Hun tegner på sit værelse.
• På sit værelse tegner hun.

Because Danish uses a reflexive possessive when the possessor is the subject of the clause.

Here the subject of the når-clause is hun, and the room belongs to that same person. So Danish uses sin/sit/sine:

• hun tegner på sit værelse

This means her own room.

If you said hendes værelse, it would usually suggest someone else’s room.

A quick comparison:

• Hun er på sit værelse. = She is in her own room.
• Hun er på hendes værelse. = She is in her room, but her refers to another female person.

Because sit agrees with the noun being possessed, not with the person who possesses it.

The noun is:

• et værelse → neuter singular

So the reflexive possessive must be:

• sit værelse

The forms are:

• sin
  • common gender singular noun
• sit
  • neuter singular noun
• sine
  • plural noun

Examples:

• sin bog
• sit værelse
• sine bøger

In Danish, på værelset / på sit værelse is very idiomatic for being in one’s room / in one’s bedroom.

So although English uses in, Danish often prefers på with rooms in this kind of everyday context.

• Hun er på sit værelse.
• Hun tegner på sit værelse.

You may also hear i sit værelse in some contexts, but på sit værelse is extremely common and often sounds more natural in ordinary Danish.

They mark where the inserted clause begins and ends.

The middle part:

• min datter lytter til

belongs with den musik and describes it. So it is set off as a relative clause:

• Det er den musik, min datter lytter til, ...

Then the sentence continues with the time clause:

• når hun tegner på sit værelse

So the commas help you see the structure:

1. Det er den musik
2. min datter lytter til
3. når hun tegner på sit værelse

In practice, the second comma shows the end of the relative clause before the når-clause starts.