É importante diminuir o barulho durante a reunião.

É importante is a very common impersonal structure in Portuguese, just like It is important in English.

• É importante diminuir o barulho = It is important to reduce the noise
• The it is not translated as a separate word here.

You could also say:

• É preciso diminuir o barulho = It is necessary to reduce the noise
• Isso é importante = That is important

But isso é importante means something slightly different: it points to a specific thing already mentioned. In your sentence, é importante is just making a general statement.

After expressions like é importante, Portuguese often uses an infinitive verb, just like English does after it is important to...

So:

• É importante diminuir o barulho
• literally: It is important to reduce the noise

Other similar examples:

• É bom descansar = It is good to rest
• É difícil entender isso = It is difficult to understand that

You do not need to conjugate diminuir here because no specific subject is being named.

Diminuir o barulho means to reduce the noise or to make things quieter.

Depending on context, it can mean:

• speak more quietly
• stop making so much noise
• turn down the volume
• reduce overall noise levels

It is a very natural phrase in Brazilian Portuguese.

A close English equivalent could be:

• Please keep the noise down
• It is important to reduce the noise

Portuguese uses definite articles much more often than English does.

So o barulho literally means the noise, but in English we might simply say noise.

In Portuguese, the article often sounds more natural:

• diminuir o barulho
• fechar a porta
• lavar as mãos

Even when English would sometimes drop the, Portuguese often keeps it.

Both can refer to noise, but they are not always used in exactly the same way.

• barulho is the more common everyday word
• ruído can sound a bit more technical, formal, or specific

Examples:

• O vizinho está fazendo barulho. = everyday, natural
• Há muito ruído nesta máquina. = more technical

In your sentence, barulho sounds very normal and natural for daily use.

Both can work, but they are slightly different.

• durante a reunião = during the meeting
• na reunião = in the meeting / at the meeting

Durante emphasizes the time period while the meeting is happening.

So:

• É importante diminuir o barulho durante a reunião
  = emphasis on keeping the noise down while the meeting is going on

You could also hear:

• É importante diminuir o barulho na reunião

That is also understandable and natural, but durante a reunião is a bit more precise for during.

Because reunião is a feminine noun in Portuguese.

So:

• a reunião = the meeting
• uma reunião = a meeting

Many Portuguese nouns ending in -ão are masculine, but not all of them. Reunião is feminine, so you must say:

• a reunião
• durante a reunião

This is something you mostly learn word by word.

The accent shows that É is the verb ser in the present tense: is.

• É importante = It is important

This is different from e without an accent:

• e = and

So the accent matters a lot:

• É importante = It is important
• e importante would be wrong in this sentence

A rough pronunciation guide is:

• re-u-ni-ÃO
• the stress is on the last syllable: -ão

Important points:

• reu is usually pronounced smoothly, almost like reh-oo
• nião ends with the nasal sound ão, which is very common in Brazilian Portuguese

A rough English-style approximation is:

• heh-oo-nee-OW̃

But the final ão is nasal, so it is not exactly like English ow.

Yes. Reduzir o barulho is also correct.

The difference is small:

• diminuir o barulho = very common and everyday
• reduzir o barulho = also correct, sometimes slightly more formal or deliberate

In everyday Brazilian Portuguese, diminuir o barulho sounds very natural.

It is both correct and natural. It sounds neutral and appropriate in many situations, especially:

• schools
• offices
• meetings
• announcements
• polite instructions

If you wanted something more direct, you might say:

• Por favor, diminuam o barulho durante a reunião.
• Vamos diminuir o barulho durante a reunião.

But your original sentence is perfectly natural as a general statement or rule.

Yes, but the original order is the most natural and standard:

• É importante diminuir o barulho durante a reunião.

You could move parts around for emphasis, for example:

• Durante a reunião, é importante diminuir o barulho.

This still sounds natural and means the same thing, but it emphasizes the time expression first.

The original version is usually the best default choice.

Yes, depending on what you mean.

For our noise, you would usually not say that literally unless the context really requires it. More natural options are:

• o barulho
• o nosso barulho if you truly want to stress our noise

For noise level, Portuguese often uses:

• o nível de ruído
• o nível de barulho in less technical contexts

But for everyday speech, diminuir o barulho is much more natural than trying to say reduce the noise level word for word.