Det kommer an på om prøveperioden står i hørselsdagboken.

Here det does not refer to a specific thing. It is a dummy subject, like it in English expressions such as It depends or It is raining.

So in Det kommer an på ..., the word det is just required to make the sentence grammatical. You usually should not try to connect it to a noun earlier in the sentence.

Å komme an på is a fixed expression meaning to depend on.

In the present tense, it becomes:

• det kommer an på = it depends on

This is a phrasal expression, so its parts stay separate in normal sentence structure:

• infinitive: å komme an på
• present: kommer an på
• past: kom an på

So even though it functions as one unit in meaning, it is written as separate words.

Here om means whether.

The sentence is talking about something that depends on whether the trial period is written in the hearing diary. That is why om is the natural choice.

Compare:

• Det kommer an på om ... = It depends on whether ...
• Hvis ... usually means if in the sense of a condition: If X happens, then Y happens

In many beginner situations, English if can correspond to both om and hvis, but here whether is the better English equivalent, so om is the correct Norwegian word.

Prøveperioden is the definite form: the trial period.

The sentence is apparently referring to a specific trial period that both speaker and listener already know about. That is why Norwegian uses the definite form with -en attached to the noun:

• en prøveperiode = a trial period
• prøveperioden = the trial period

Using the definite form is very common when the thing is already known from the context.

In Norwegian, stå is often used when information is written, listed, or appears in a text, form, document, sign, or similar source.

So:

• Det står i boka = It says so in the book / It is written in the book
• Navnet står på listen = The name is on the list

That is why prøveperioden står i hørselsdagboken sounds natural: it means the trial period is written down or recorded there.

This use of stå is very common and is worth learning as a set pattern.

Hørselsdagboken is a compound noun.

It is built from:

• hørsel = hearing
• dagbok = diary
• -en = the definite ending, so dagboken = the diary

Together:

• hørselsdagbok = hearing diary
• hørselsdagboken = the hearing diary

A useful thing to remember is that in Norwegian compounds, the definite ending goes on the last part of the compound.

Because om prøveperioden står i hørselsdagboken is a subordinate clause.

In Norwegian subordinate clauses, the normal order is:

• subject + verb

So:

• om prøveperioden står i hørselsdagboken

This is different from main clauses, where Norwegian often uses verb-second word order.

Compare:

• main clause: Prøveperioden står i hørselsdagboken.
• subordinate clause: ... om prøveperioden står i hørselsdagboken.

So the word order here is exactly what you should expect after om.

Det kommer an på is completely normal and natural in everyday Norwegian. It works well in both speech and writing.

A somewhat more formal or abstract alternative is:

• Det avhenger av ... = It depends on ...

For example:

• Det kommer an på om prøveperioden står i hørselsdagboken.
• Det avhenger av om prøveperioden står i hørselsdagboken.

Both are correct, but det kommer an på often feels a bit more conversational.

Yes, om can also mean about, but not in this sentence.

For example:

• en bok om språk = a book about language

Here, though, om introduces a clause:

• om prøveperioden står i hørselsdagboken

When om is followed by a whole clause like this, it often means whether.

So the structure helps you identify the meaning:

• om + noun can sometimes mean about
• om + clause often means whether

I is natural because a diary, book, or document is treated as something information is written in.

So Norwegian commonly says:

• i boka = in the book
• i journalen = in the record/journal
• i dagboken = in the diary

If the idea were more about a surface, label, or list, other prepositions could appear in other contexts, but with a diary or written record, i is the normal choice here.