Jeg kan høre torden derude.

In Danish, kan + infinitive often works like English can + verb with senses:

• Jeg kan høre ... = I can hear ...
• It often describes what you are able to perceive right now, not only general ability.

So Jeg kan høre torden derude sounds very natural for noticing a sound at the moment.

You can also say Jeg hører torden derude, but jeg kan høre is often the more idiomatic choice when talking about hearing something happening.

Because kan is a modal verb, and after modal verbs Danish uses the bare infinitive.

So:

• jeg kan høre
• jeg vil høre
• jeg skal høre

Not:

• jeg kan at høre

This is similar to English:

• I can hear
• not I can to hear

Here, kan mainly means that the speaker is able to perceive the sound at this moment.

With verbs of perception like høre and se, kan is very often used in a way that sounds natural and immediate:

• Jeg kan høre dig. = I can hear you.
• Kan du se det? = Can you see it?

So yes, kan can express ability, but in sentences like this it often simply matches natural English usage with can hear or can see.

Because torden here is being used as a general, uncountable phenomenon, just like English thunder in I can hear thunder.

So Danish says:

• Jeg kan høre torden.

not usually:

• Jeg kan høre en torden.

This is similar to other uncountable or general nouns:

• Jeg kan høre musik.
• Jeg kan høre regn.

If you were talking about something more specific, the wording might change, but in this sentence the article is naturally omitted.

Derude means something like:

• out there
• outside
• out there somewhere

It is written as one word in Danish.

It is an adverb made from:

• der = there
• ude = out / outside

Together, derude points to something outside or at some distance from the speaker.

Compare:

• ude = outside / out
• derude = out there

So Jeg kan høre torden derude suggests the thunder is somewhere outside, away from the speaker.

This is an important distinction.

• høre = to hear
• lytte (til) = to listen (to)

So in this sentence, høre is correct because thunder is something you perceive with your ears, whether or not you are trying to.

Examples:

• Jeg kan høre torden. = I can hear thunder.
• Jeg lytter til musik. = I am listening to music.

You would not normally use lytte here unless you specifically meant that you were intentionally listening for the thunder.

Yes, you could.

Both are grammatical:

• Jeg kan høre torden derude
• Jeg hører torden derude

The difference is mostly one of natural phrasing and nuance:

• Jeg kan høre ... often sounds a little more like immediate perception: I can hear ...
• Jeg hører ... can sound slightly more neutral: I hear / am hearing ...

In everyday Danish, kan høre is very common in this kind of sentence.

In a normal Danish main clause, the finite verb usually comes early, and if the subject comes first, the order is:

• subject + finite verb + infinitive/complements

So here:

• Jeg = subject
• kan = finite verb
• høre = infinitive
• torden = object
• derude = adverb

That gives:

• Jeg kan høre torden derude.

You cannot place the verbs in any order you like. For example, Jeg høre kan ... is incorrect.

Yes. Danish often allows another element to come first for emphasis, but then the finite verb still stays in second position.

For example:

• Derude kan jeg høre torden.

This puts emphasis on derude.

That is a normal feature of Danish word order, often called the V2 rule: the finite verb comes second in main clauses.

You would normally add ikke after the finite verb:

• Jeg kan ikke høre torden derude.

That means I can’t hear thunder out there.

This is a very common Danish pattern:

• Jeg kan ikke se det.
• Han vil ikke gå.

So the negative word ikke usually comes after the finite verb in a main clause like this.

Høre can be tricky for English speakers because of ø.

A rough guide:

• ø is a rounded front vowel, somewhat like the vowel in French peu or German schön
• the r in Danish is softer than in English
• the final -e is a light unstressed vowel

So høre is roughly something like HUH-ruh, but with rounded lips on the first vowel. That English-style approximation is not exact, but it can help as a starting point.

The main thing to notice is that ø is not like English o.

Derude is an adverb.

It tells you where the thunder is being heard from: outside / out there.

Danish has many similar adverbs:

• derinde = in there
• deroppe = up there
• dernede = down there

So derude fits into a very common Danish pattern of location words.