À noite, o barulho da vizinhança diminui.

À noite means at night / in the evening, depending on context.

In Brazilian Portuguese, à noite is the most standard and common way to say at night in a sentence like this.

• À noite, o barulho da vizinhança diminui. = At night, the neighborhood noise decreases.

You may also hear de noite, especially in speech, and it often means roughly the same thing. But for learners, à noite is a very safe and natural choice.

A useful comparison:

• de manhã = in the morning
• à tarde = in the afternoon
• à noite = at night / in the evening

So à noite is a fixed time expression you should learn as a chunk.

À is a contraction of:

• a = the preposition to / at
• a = the feminine definite article the

So:

• a + a = à

In this expression, Portuguese uses that contraction before noite, which is a feminine noun:

• a noite → à noite

This grave accent is called crase in Portuguese. It does not mark stress like the acute accent does. Instead, it shows that two a sounds merged into one.

Important:

• à noite = correct
• a noite = usually incorrect in this meaning

Portuguese often uses definite articles more often than English does.

So where English might say:

• Neighborhood noise decreases at night

Portuguese naturally says:

• o barulho da vizinhança diminui

Here, o means the, and barulho is a masculine singular noun, so it takes o.

This is very normal in Portuguese. Articles are frequently used even when English would omit them.

Da vizinhança literally means of the neighborhood.

It is made of:

• de = of / from
• a = the
• de + a = da

So:

• o barulho da vizinhança = the noise of the neighborhood = more naturally in English, the neighborhood noise or the noise from the neighborhood

This structure is very common in Portuguese:

• o carro da professora = the teacher’s car
• a porta da casa = the door of the house
• o som da rua = the sound/noise of the street

Usually vizinhança means the neighborhood or the surrounding area / nearby residents as a group, depending on context.

In this sentence, o barulho da vizinhança suggests:

• the noise coming from the neighborhood
• the noise made by nearby people/houses/streets

So it is broader than just the neighbors.

If you wanted to refer more directly to the neighbors, you would often say:

• os vizinhos = the neighbors

Compare:

• o barulho da vizinhança = the neighborhood noise / the noise from nearby
• o barulho dos vizinhos = the neighbors’ noise

Diminui is the 3rd person singular present tense of the verb diminuir = to decrease / to lessen / to get smaller / to go down.

Conjugation:

• eu diminuo = I decrease
• você/ele/ela diminui = you/he/she decreases
• nós diminuímos = we decrease
• eles/elas diminuem = they decrease

In the sentence, the subject is:

• o barulho da vizinhança = the neighborhood noise

That subject is singular, so the verb must also be singular:

• o barulho ... diminui

The present tense here expresses a general fact or usual pattern:

• À noite, o barulho da vizinhança diminui. = At night, the neighborhood noise goes down / tends to decrease.

This is not necessarily about right now. It is more like a general truth or routine situation.

English does the same thing:

• At night, the noise decreases.

So this is a very normal use of the present tense in both languages.

In Brazilian Portuguese, diminui is pronounced approximately like:

• jee-mee-NOO-ee

A more careful breakdown:

• di sounds like jee in many Brazilian accents
• mi = mee
• nui is usually pronounced as two syllables: noo-ee

So:

• di-mi-nu-i
• 4 syllables

The stress falls on the last i sound area:

• di-mi-nu-i

Also, notice that diminui is spelled without an accent mark, but that does not mean it is pronounced like English diminoo. The ending is clearly heard.

A rough Brazilian Portuguese pronunciation is:

• vee-zeen-YAN-sa

Breakdown:

• vi = vee
• zi = zee
• nh = a palatal sound like ny in canyon
• ça = sa

So:

• vi-zi-nhan-ça

The nh is important:

• nh ≈ ny

Examples with the same sound:

• manhã
• senhorinha
• vinho

And ç always gives an s sound before a, o, u:

• ça = sa

Yes. You can also say:

• O barulho da vizinhança diminui à noite.

This means the same thing.

The version with À noite at the beginning emphasizes the time first, which is very natural when setting the scene.

So both are correct:

• À noite, o barulho da vizinhança diminui.
• O barulho da vizinhança diminui à noite.

The first one sounds a bit more like:

• At night, ...

The second one sounds a bit more like:

• The neighborhood noise decreases at night.

The comma is very natural here because À noite is an introductory time expression.

• À noite, o barulho da vizinhança diminui.

This is the clearest and most standard punctuation.

You may sometimes see short adverbial expressions without a comma, especially in informal writing:

• À noite o barulho da vizinhança diminui.

That is not shocking, but the comma is better style in a sentence like this, especially for learners and in careful writing.

Not in this sentence.

Portuguese normally needs the full expression:

• à noite

So:

• À noite, o barulho da vizinhança diminui. = correct
• Noite, o barulho da vizinhança diminui. = incorrect

Unlike English, where you can sometimes say things like nights are quiet, Portuguese usually needs the proper preposition/article combination in this kind of time phrase.

Usually barulho means noise, so it often has a negative or unwanted feeling.

Examples:

• Muito barulho = a lot of noise
• O barulho me incomoda = the noise bothers me

If you want a more neutral word for sound, Portuguese often uses:

• som = sound

So:

• barulho da vizinhança suggests noisy surroundings
• som da vizinhança would sound more neutral and less natural in this specific context

In this sentence, barulho is the right choice because it suggests the neighborhood is noisy and then gets quieter at night.