Learn Hardcore Portuguese (Portugal): Um pouco de música muda sempre o meu humor antes do exame. - A bit of music always changes my mood before the exam.

um pouco de música = some / a bit of music in general, not specific
- A general statement: any music helps change my mood.
um pouco da música = a bit of the music, referring to specific music already known from context
- For example, you’re listening to a particular song/playlist and you say:
  - Quero ouvir só um pouco da música. – I just want to listen to a bit of the music (that is playing / that we talked about).

In the original sentence, we mean music in general, so um pouco de música is correct.

Why is the verb muda and not mudo or mudam?

The subject of the sentence is um pouco de música:

um pouco de música = a bit of music → this is 3rd person singular

The verb mudar (to change) in the present tense:

eu mudo – I change
tu mudas – you change
ele/ela muda – he/she/it changes

Since um pouco de música = it (singular), we use ele/ela muda → muda.

So:

Um pouco de música muda…
A bit of music changes…

Mudo would mean “I change” (or the adjective “mute”) and mudam would be plural (they change), which doesn’t match the singular subject.

Could I say A música muda sempre o meu humor instead of Um pouco de música muda sempre o meu humor?

Yes, grammatically you can:

A música muda sempre o meu humor. – Music always changes my mood.

However, there is a nuance:

Um pouco de música emphasizes that just a little music is enough to change your mood.
A música is more general: music as a whole, without the idea of a small amount.

Both are correct; they just highlight different things.

Why is sempre placed after muda in muda sempre? Could it be sempre muda instead?

Both positions are possible in European Portuguese:

Um pouco de música muda sempre o meu humor…
Um pouco de música sempre muda o meu humor…

They are both grammatical and very natural. The difference is subtle:

muda sempre slightly highlights the action “changes” as something that always happens.
sempre muda can feel a bit more emphatic on the frequency “always”.

In everyday speech, both orders are used, and in this sentence they are practically interchangeable.

Why do we say o meu humor and not just meu humor?

In European Portuguese, it is very common (and often preferred) to use a definite article + possessive:

o meu humor – my mood
a minha casa – my house
os meus livros – my books

So:

o + meu + humor

Saying meu humor without the article is not wrong, but in European Portuguese it can sometimes sound more formal, old-fashioned, or poetic in many contexts. In everyday speech, o meu humor is more natural.

Could I say muda sempre o humor instead of muda sempre o meu humor?

You can, but the meaning changes slightly:

muda sempre o meu humor – always changes my mood (specifically yours)
muda sempre o humor – always changes the mood (more general/impersonal; could mean the atmosphere, people’s mood in general)

In the original sentence, you are talking about your own mood, so o meu humor is the clear and natural choice.

What does humor mean here? Is it like English humour or mood?

In Portuguese, humor most commonly means mood, as in:

Estou de bom humor. – I’m in a good mood.
Ele está de mau humor. – He’s in a bad mood.

It can also relate to humour / comedy in some contexts, especially in combinations like:

programa de humor – comedy show

But in the sentence Um pouco de música muda sempre o meu humor, it clearly means my mood.

Why is it antes do exame and not antes de exame?

Antes de can be used both:

With an article → antes do exame
- de + o exame → do exame
- Means before the exam (a specific exam, known from context).
Without an article → antes de exame
- This is possible, but it sounds less natural here in European Portuguese; it would feel more generic or technical, like “before exams (in general)” in some contexts.

In everyday speech, when you refer to a specific exam you have to take, you normally say:

antes do exame – before the exam

So antes do exame is the natural choice.

What exactly is do in do exame?

Do is a contraction of the preposition de and the definite article o:

de + o = do

So:

antes de + o exame → antes do exame

Similar contractions:

de + a = da → da escola – of the school
de + os = dos → dos livros – of the books
de + as = das → das aulas – of the classes

In antes do exame, you are literally saying before of-the exam → before the exam.

Why is the verb in the present tense (muda) if we’re talking about something that happens regularly, not just once?

In Portuguese (as in English), the simple present is used for:

General truths
Habits / repeated actions

So:

Um pouco de música muda sempre o meu humor antes do exame.
= A bit of music always changes my mood before the exam.

This is a habitual action, so the present tense (muda) is exactly what we use. You don’t need an extra word like costuma (though it’s possible: Um pouco de música costuma mudar… – “A bit of music usually tends to change…”).

Is música here countable or uncountable in Portuguese?

In this sentence, música is used as an uncountable noun, like English music:

um pouco de música – a bit of music

You would normally not say um pouco de músicas here; that would sound strange, as if you’re counting songs or pieces of music.

If you want to count, you use words like:

canção / música (in the sense of song)
- duas músicas – two songs

But in our sentence, we’re talking about music as a general thing, so the singular uncountable música with um pouco de is correct and natural.