Šapućemo da bi slavljenik čuo samo muziku.

Da bi introduces a purpose clause. In English, it usually corresponds to so that or in order that.

So the sentence structure is:

• Šapućemo = we are whispering / we whisper
• da bi slavljenik čuo samo muziku = so that the celebrant would hear only the music

It tells you the goal of the action in the main clause.

It looks past-like, but here it is not functioning as a simple past tense.

Čuo is the l-participle of čuti and, together with bi, it forms the conditional:

• bi čuo = would hear

So in this sentence:

• da bi slavljenik čuo = so that the celebrant would hear

This is a very common pattern in Serbian purpose clauses.

Because bi belongs to the subordinate clause, not the main clause.

The subject of the main clause is:

• mi implied in šapućemo = we

But the subject of the clause after da bi is:

• slavljenik = the celebrant

Since slavljenik is third person singular, the correct auxiliary is bi.

Compare:

• Šapućemo da bi slavljenik čuo... = We whisper so that he would hear...
• Šapućemo da bismo čuli... = We whisper so that we would hear...

Because it agrees with slavljenik, which is a masculine singular noun.

In this construction, the participle changes for gender and number:

• slavljenik bi čuo = the male celebrant would hear
• slavljenica bi čula = the female celebrant would hear
• slavljenici bi čuli = the celebrants would hear

So čuo is chosen because the subject is masculine singular.

Because čuti takes a direct object, and the direct object goes in the accusative case.

• nominative: muzika = music
• accusative: muziku

So:

• čuti muziku = to hear music

This is a standard case pattern in Serbian.

Slavljenik means the person being celebrated.

In many contexts, it means:

• the birthday person
• the celebrant
• the guest of honor

It is not just any guest. It specifically refers to the person whose celebration it is.

The feminine form is:

• slavljenica

Here samo modifies muziku, so the meaning is:

• only the music

In other words, the celebrant should hear music and nothing else.

Word order matters for focus. For example:

• samo muziku = only the music
• samo slavljenik = only the celebrant

So in your sentence, samo clearly limits muziku.

Sometimes you may hear da + present for purpose, but da bi + participle is the clearest and safest pattern for so that / in order that, especially when the subject changes.

This sentence has two different subjects:

• we whisper
• the celebrant hears

Because of that, da bi slavljenik čuo sounds very natural and clearly expresses purpose.

A learner should treat da bi + participle as the standard model here.

It can mean either, depending on context.

Serbian present tense often covers both:

• we whisper
• we are whispering

So šapućemo could describe:

• a general action or habit
• something happening right now

Without more context, both are possible.

Because Serbian has no articles like the or a/an.

Whether something is definite or indefinite is usually understood from:

• context
• word order
• the situation

So slavljenik can mean the celebrant, and muziku can mean the music or just music, depending on the context.

These are important sounds for English speakers:

• š sounds like sh in ship
• č sounds like ch in church
• ć is a softer sound than č; English does not have an exact equivalent, but it is somewhat like a very soft ty/ch sound

So roughly:

• Šapućemo ≈ sha-poo-će-mo
• čuo starts with č, not ć
• muziku has a clear z sound

A rough pronunciation of the whole sentence is:

• Sha-poo-će-mo da bi slav-ye-nik choo-o sa-mo moo-zee-koo

That is only approximate, but it helps with the main consonants.