O nervoso passa quando eu escuto música.

Here o nervoso is a noun-like use of nervoso. It refers to nervousness, an anxious feeling, or being worked up.

In more formal Portuguese, you would often see o nervosismo for nervousness. But in everyday Brazilian speech, people do sometimes use o nervoso to talk about that emotional state.

So this sentence sounds like:

• the nervousness goes away
• the anxiety passes
• feeling nervous passes

Portuguese often uses the definite article with abstract ideas, states, and qualities more than English does.

So o nervoso is not literally the nervous in the way English would say it. It is more like:

• the nervousness
• that nervous feeling

This kind of structure is common in Portuguese, where an adjective can be used like a noun.

Yes, it can sound natural in colloquial Brazilian Portuguese, especially in speech.

That said, many learners will also hear or learn more standard-sounding versions such as:

• O nervosismo passa quando eu escuto música.
• O nervoso vai embora quando eu escuto música.
• Eu fico menos nervoso quando eu escuto música.

So o nervoso passa is understandable and natural in the right context, but o nervosismo passa may sound a little more neutral or formal.

Here passa comes from the verb passar, and it means something like:

• passes
• goes away
• wears off

So o nervoso passa means that the nervous feeling stops, fades, or goes away.

This is a very common use of passar in Portuguese:

• A dor passou. = The pain went away.
• A raiva passa. = The anger passes.

Because Portuguese does not use a preposition here.

In English, we say listen to music.
In Portuguese, you simply say:

• escutar música
• ouvir música

So there is no to equivalent in this structure. You do not say escuto para música.

This is something English speakers often need to get used to: verbs do not always take the same prepositions across languages.

Yes, ouço would also be possible.

Both verbs can work:

• escutar música
• ouvir música

In everyday Brazilian Portuguese, both are common. A rough distinction is:

• ouvir = to hear / to listen
• escutar = often feels a little more like to listen attentively

But in many real situations, Brazilians use them interchangeably.

So these both sound natural:

• O nervoso passa quando eu escuto música.
• O nervoso passa quando eu ouço música.

Because música here means music in general, not a specific piece of music.

So:

• escuto música = I listen to music
• escuto uma música = I listen to a song
• escuto a música = I listen to the song / the music (specific)

Portuguese often leaves out the article when speaking generically like this.

Yes, it could be omitted.

Portuguese is a pro-drop language, which means the subject pronoun is often left out when the verb already makes the subject clear.

So both are natural:

• quando eu escuto música
• quando escuto música

The version with eu can add:

• a little emphasis
• extra clarity
• a slightly more explicit rhythm in speech

Because this sentence describes a habitual or general situation.

Quando eu escuto música means something like:

• when I listen to music
• whenever I listen to music

It refers to something that regularly happens, so the present indicative is natural.

If you were talking about a future event, Portuguese often uses the future subjunctive:

• Quando eu escutar música, vou me acalmar. = When I listen to music, I’ll calm down.

So:

• quando eu escuto = habitual / general
• quando eu escutar = future situation

Yes. A very natural alternative is:

• Quando eu escuto música, o nervoso passa.

This means the same thing. Portuguese often allows this kind of flexibility, especially with time clauses like quando...

The difference is mostly about focus:

• O nervoso passa quando eu escuto música.
  Focus starts on the nervousness going away.
• Quando eu escuto música, o nervoso passa.
  Focus starts on the condition or moment: when I listen to music.

Quando means when here, introducing a time clause.

In this sentence, it has the sense of:

• when
• whenever

Because the sentence expresses a general pattern, quando is closer to whenever in meaning:

• O nervoso passa quando eu escuto música. = My nervousness goes away whenever I listen to music.

So quando does not only refer to one single moment; it can also describe repeated situations.