Cum ventus fortis est, sonus dulcis in arundinibus auditur.

Here cum is a conjunction meaning when.

Latin has two different uses of cum:

• cum
  • ablative noun = with
    • cum amico = with a friend
• cum
  • a whole clause = when, since, or sometimes although
    • cum ventus fortis est = when the wind is strong

In this sentence, cum is followed by a full clause with a subject and verb, so it must be the conjunction.

That is a very common question. Cum can be followed by either the indicative or the subjunctive, depending on the sense.

Here, cum ventus fortis est is a straightforward temporal clause, meaning when the wind is strong. For that simple time sense, Latin can use the indicative.

Very roughly:

• cum
  • indicative often gives a plain time meaning: when
• cum
  • subjunctive often gives a more descriptive background sense, or a causal sense such as since, or sometimes although

So est is perfectly normal here because the sentence is simply stating a condition of time or circumstance.

Because fortis is an adjective describing the noun ventus.

• ventus = wind
• fortis = strong

Since ventus is masculine singular nominative, the adjective must agree with it in gender, number, and case. So we get:

• ventus fortis = a strong wind or the wind is strong

Forte would not work here as an adjective agreeing with ventus. In many contexts, forte is an adverb, meaning something like by chance, not strong.

Ventus is nominative singular.

You know it is the subject because:

• est is third person singular, so it needs a singular subject
• ventus is a nominative singular noun
• fortis agrees with ventus, confirming that they belong together

So ventus fortis est literally means the wind is strong.

Auditur is the present passive indicative, third person singular, of audio.

Its basic breakdown is:

• audio = I hear
• audit = he, she, it hears
• auditur = he, she, it is heard

So in this sentence:

• sonus dulcis auditur = a sweet sound is heard

Because it is passive, the sentence does not say who hears the sound. Latin often leaves that unstated when it is obvious, general, or unimportant.

Because Latin is using the passive construction:

• sonus dulcis auditur = a sweet sound is heard

Here sonus is nominative singular, so it is the grammatical subject of the passive verb auditur.

English often prefers an active phrasing such as you hear a sweet sound or one hears a sweet sound, but Latin is perfectly happy to say a sweet sound is heard.

Dulcis is an adjective modifying sonus.

They agree in case and number, and they match in sense:

• sonus = nominative singular masculine
• dulcis = nominative singular, matching sonus

So:

• sonus dulcis = a sweet sound or the sweet sound

Even though dulcis has the same form for masculine and feminine in the nominative singular, here it is masculine because it agrees with sonus, which is masculine.

Because in with the ablative usually expresses location.

So:

• in arundinibus = in the reeds or among the reeds

The noun arundinibus is ablative plural from arundo, arundinis, meaning reed.

A useful rule is:

• in
  • ablative = in, on, among in a static location
• in
  • accusative = into, showing motion toward something

Here there is no motion into the reeds, only location, so the ablative is correct.

Because arundo means reed, and the sentence is talking about reeds as a group or setting, not just one single reed.

So:

• in arundine = in a reed
• in arundinibus = in the reeds or among the reeds

The plural feels natural here, since wind moving through multiple reeds produces the sound.

It can suggest either, depending on how literally you want to take it.

Latin in with the ablative can cover a range of location ideas that English divides more sharply. So in arundinibus could be understood as:

• in the reeds
• among the reeds

In natural English, among the reeds may sound a little more idiomatic in this context, but the Latin itself is fine either way.

Yes, it could come before. Latin word order is much freer than English word order.

So both of these are possible:

• sonus dulcis
• dulcis sonus

Both mean sweet sound. The difference is usually one of style, emphasis, or rhythm, not basic grammar.

In your sentence, sonus dulcis is simply a natural word order.

Because Latin does not have articles like English a, an, and the.

So:

• ventus can mean wind, a wind, or the wind
• sonus can mean sound, a sound, or the sound
• arundinibus can mean reeds or the reeds

The context tells you which English article makes the most sense. That is why the same Latin sentence can be translated in slightly different but equally correct ways.

Yes, that is a very reasonable understanding.

Because both clauses are in the present tense, the sentence can sound like a general truth or repeated situation:

• When the wind is strong, a sweet sound is heard in the reeds
• Whenever the wind is strong, a sweet sound is heard in the reeds

English chooses between when and whenever based on style and context, but the Latin can support that general sense.