Det lyder, som om bowlingkuglen væltede keglerne.

Som om means as if or like in this kind of sentence.

So Det lyder, som om ... means It sounds as if ... or It sounds like ....

You cannot normally replace it with at here. Det lyder, at ... would not sound natural in Danish.

The comma separates the main clause from the clause introduced by som om.

Here:

• Det lyder = main clause
• som om bowlingkuglen væltede keglerne = clause after it

In modern Danish, both Det lyder som om ... and Det lyder, som om ... can be seen, depending on comma style. So the comma is not something to panic about here.

Yes. Som om introduces a subordinate clause.

That matters because Danish main clauses and subordinate clauses do not always behave the same way. In this sentence, the word order looks simple:

• bowlingkuglen = subject
• væltede = verb
• keglerne = object

If you added a word like ikke, the subordinate-clause pattern would be clearer:

• Det lyder, som om bowlingkuglen ikke væltede keglerne.

Because Danish loves compound nouns.

bowlingkuglen is built from:

• bowling
• kugle = ball
• -n / -en = the definite ending

So:

• en bowlingkugle = a bowling ball
• bowlingkuglen = the bowling ball

English usually writes compounds more separately than Danish does, but Danish often joins them into one word.

Because keglerne means the pins, while kegler means just pins.

The forms are:

• en kegle = a pin
• kegler = pins
• keglerne = the pins

So the ending -ne is the definite plural ending.

Væltede is the past tense of vælte.

So:

• vælte = to tip over / to knock over
• væltede = tipped over / knocked over

In this sentence, it means that the bowling ball knocked the pins over.

Because Danish often uses past tense after som om when describing what something seemed to be like.

So Det lyder, som om bowlingkuglen væltede keglerne means something like:

• It sounds as if the bowling ball knocked over the pins

This does not necessarily mean the speaker saw it happen. It is an impression based on the sound.

You could also hear a perfect form in some contexts, such as har væltet, but væltede is perfectly natural here.

Not necessarily.

Det lyder, som om ... expresses an impression or inference. The speaker is judging from what they hear, not stating a confirmed fact.

So the idea is:

• That is what it sounded like not
• I know for certain that it happened

Because Danish usually puts the definite article at the end of the noun instead of using a separate word like English the.

Compare:

• en kugle = a ball
• kuglen = the ball
• en kegle = a pin
• keglerne = the pins

So the definiteness is built into the noun itself.

Yes, that is possible.

The difference is mainly one of aspect and viewpoint:

• væltede presents it as a past event in a simple way
• har væltet focuses more on the completed result

In many everyday situations, both would be understandable. The original version with væltede is very natural for describing what it sounded like happened.