Wir hören den ersten Crack deutlich.

Because Crack is the direct object of hören, and hören takes the accusative case.

• wir = subject, nominative
• den ersten Crack = direct object, accusative

If Crack is masculine singular, the accusative article is den:

• nominative: der Crack
• accusative: den Crack

So Wir hören den ersten Crack is grammatically correct.

Because erste here is an ordinal number used like an adjective, and it follows the definite article den.

In den ersten Crack:

• den = masculine accusative singular definite article
• after that, the adjective-like word takes the ending -en

So:

• der erste Crack = nominative
• den ersten Crack = accusative

This is the normal weak adjective ending after a definite article.

Yes. Ordinal numbers such as erste, zweite, dritte, etc. behave like adjectives in German.

That means they change their endings depending on:

• case
• gender
• number
• article type

So in this sentence, erste becomes ersten because it is modifying a masculine accusative noun: Crack.

Because Crack is a noun, and all nouns are capitalized in German.

So even if the word comes from English, it still follows German spelling rules:

• der Crack
• ein Crack
• den ersten Crack

It can be used in German as a borrowed word from English, especially for a sharp cracking sound or in certain technical or descriptive contexts.

The important grammar point here is that German treats it like a regular noun:

• it has a gender
• it takes case endings through the article
• it is capitalized

In this sentence, it is being treated as a masculine noun: der Crack.

Because deutlich is an adverb, and adverbs often come after the object in a neutral German sentence.

So:

• Wir hören = subject + verb
• den ersten Crack = object
• deutlich = adverb

That gives the natural order: Wir hören den ersten Crack deutlich.

German word order is flexible, so other orders are possible for emphasis, but this version sounds neutral and normal.

Here, deutlich is an adverb, describing how we hear something.

It means something like:

• clearly
• distinctly
• noticeably

It does not change its form here. Unlike adjectives before nouns, adverbs do not take endings in this kind of use.

Because German main clauses normally follow the V2 rule: the finite verb comes in the second position.

In this sentence:

• position 1: Wir
• position 2: hören

Then the rest follows: den ersten Crack deutlich

So the sentence follows standard German main-clause word order.

Yes, that is grammatically possible, but it changes the emphasis.

German allows different elements in the first position of a main clause. If you put deutlich first, the verb still has to stay second:

• Deutlich hören wir den ersten Crack.

This sounds more marked or stylistic, with stronger focus on deutlich. The original sentence is more neutral.

Because wir is the subject of the sentence, and German only needs it once here.

• wir = we
• hören = hear

So Wir hören simply means we hear.

German verbs are conjugated, so hören already matches wir:

• ich höre
• du hörst
• er/sie/es hört
• wir hören
• ihr hört
• sie/Sie hören

When it means to hear something, yes, it normally takes a direct object in the accusative.

Examples:

• Ich höre die Musik.
• Wir hören den Lärm.
• Sie hört einen Knall.

So in your sentence, den ersten Crack is in the accusative because it is what is being heard.

The ö is not pronounced like a normal English o.

A useful approximation is:

• say e as in bed
• while rounding your lips as if saying o

So hören sounds roughly like HER-en with rounded lips on the first vowel, though that is only an approximation.

Also note:

• h is pronounced here
• the r in many accents of German is weak or vocalized after the vowel
• the final -en is usually a light unstressed ending

Yes. In this sentence, deutlich suggests that the sound is heard in a clear, unmistakable way.

Depending on context, English translations could include:

• clearly
• distinctly
• plainly

So if the meaning has already been given to you, the key thing to notice is that deutlich is the adverb describing the manner of hearing.