L'acustica aiuta il soprano.

Because la becomes l' before a vowel. This is called elision.

• la acustica → l'acustica

It is still the feminine singular definite article, just shortened for smoother pronunciation.

Yes. The article l' here stands for la, so acustica is feminine singular.

In this sentence:

• l'acustica = the acoustics / acoustics
• feminine singular noun

Even though English often uses acoustics as a plural-looking word, Italian acustica is grammatically singular.

Aiuta is the third-person singular present indicative of aiutare (to help).

So it means:

• he/she/it helps
• helps

Here it agrees with the subject l'acustica, which is singular.

Full breakdown:

• aiutare = infinitive
• aiuta = helps

In the normal Italian word order, the sentence is:

• L'acustica = subject
• aiuta = verb
• il soprano = direct object

So the structure is:

• The acoustics help the soprano

Italian often follows subject + verb + object, just like English.
So the first noun phrase, l'acustica, is naturally understood as the doer of the action.

Because aiutare takes a direct object in Italian.

So you say:

• aiutare qualcuno = to help someone

Not:

• aiutare a qualcuno in this meaning

That is why the sentence is:

• L'acustica aiuta il soprano

and not L'acustica aiuta al soprano.

In Italian, soprano is often treated as a masculine noun as a musical term, so il soprano is very normal.

However, in modern usage you may also encounter la soprano when referring specifically to a female singer. So this is one of those words where usage can vary somewhat by context and style.

In this sentence, just focus on the fact that:

• il soprano is a correct form
• it means the soprano

It can depend on context.

Soprano can refer to:

• a soprano singer
• the soprano voice/register

In this sentence, since aiutare usually refers to helping a person or performer, learners will often understand il soprano as the soprano singer.

Normally, no. Italian uses articles much more regularly than English.

So:

• l'acustica
• il soprano

sound natural, while leaving the articles out would usually sound incomplete or unnatural in a sentence like this.

A simple pronunciation guide is:

la-KOO-sti-ka ah-YOO-ta eel so-PRA-no

More carefully, with stress:

• acùstica
• aiùta
• sopràno

And because of the elision, L'acustica is pronounced smoothly as one unit.

Often, yes, but the grammar is different.

English commonly uses acoustics, which looks plural.
Italian commonly uses acustica, which is singular.

So even though the meaning may match English acoustics, the Italian verb stays singular:

• L'acustica aiuta...
• not L'acustica aiutano...

Almost, but not perfectly.

Word-by-word:

• L' = the
• acustica = acoustics / acoustics quality
• aiuta = helps
• il soprano = the soprano

A natural English translation depends on context, but grammatically the Italian sentence is very straightforward: subject + verb + object.