Я почти не слышу музыку в метро.

Yes. Russian often omits the subject pronoun when it is clear from the verb ending.

• слышу already means I hear / I am hearing
• so Почти не слышу музыку в метро is completely natural

Including я can make the sentence:

• a little more explicit
• slightly more emphatic
• useful for contrast, as in Я почти не слышу музыку, а он слышит

So я is not required, but it is not wrong at all.

почти не literally means almost not, but in natural English it is usually:

• hardly
• barely
• almost don’t

So Я почти не слышу музыку в метро means something like:

• I can barely hear music in the metro
• I hardly hear music in the metro

This is a very common Russian pattern:

• Я почти не сплю = I hardly sleep
• Он почти не ест мясо = He hardly eats meat

Because почти modifies the whole negative idea: almost do not hear.

So Russian says:

• почти не слышу = I almost don’t hear / I barely hear

If you said не почти слышу, that would sound unnatural and would mean something like I don’t almost hear, which is not how Russian normally expresses this idea.

So learners should remember почти не + verb as a common pattern.

Because слышать and слушать mean different things.

• слышать = to hear
  passive perception: sound reaches your ears
• слушать = to listen (to)
  active attention: you are intentionally listening

In this sentence, the idea is that the speaker cannot perceive the music well in the noisy metro, so слышу is the right choice.

Compare:

• Я слушаю музыку = I am listening to music
• Я слышу музыку = I hear music

слышу is the 1st person singular present tense form of слышать.

That is why it matches я:

• я слышу = I hear

A few other forms are:

• ты слышишь = you hear
• он/она слышит = he/she hears
• мы слышим = we hear
• они слышат = they hear

So the ending -у here signals I.

Because this sentence describes an ongoing situation, not a single completed result.

• слышать is imperfective
• услышать is perfective

In Russian:

• imperfective is used for repeated, ongoing, general, or uncompleted actions
• perfective usually refers to a completed event or a successful result

So:

• Я почти не слышу музыку в метро = I can barely hear music in the metro / a general or current situation
• Я услышу музыку = I will hear the music / a future completed event

Also, perfective verbs do not normally have a true present meaning in Russian. Their “present” forms usually refer to the future.

Because музыка is the direct object of слышу.

The dictionary form is:

• музыка = nominative

But after a transitive verb like слышать, the direct object normally goes into the accusative:

• слышу музыку

For feminine nouns ending in -а, the accusative singular usually changes to -у:

• музыка → музыку
• книга → книгу
• машина → машину

So музыку is the expected accusative form.

Yes, sometimes. This is a very common learner question.

With negation, Russian can use either:

• не слышу музыку
• не слышу музыки

Both are possible, but the nuance can differ.

A simple way to think about it:

• музыку (accusative) often treats the object more concretely or more like a specific thing
• музыки (genitive) often sounds more like any music or emphasizes absence

So:

• Я не слышу музыку = I don’t hear the music / I don’t hear music
• Я не слышу музыки = I don’t hear any music

In modern everyday Russian, accusative after negation is quite common, so the sentence with музыку is perfectly understandable and natural. But learners should know that музыки is also a real and important alternative.

Here в means in, referring to location.

When в expresses location, Russian normally uses the prepositional case:

• в школе = at school
• в городе = in the city
• в метро = in the metro

So the meaning is location: the speaker is in the metro.

If в expresses motion into something, Russian usually uses the accusative instead:

• иду в школу = I am going to school
• вхожу в метро = I enter the metro

In this sentence, it is location, not motion.

Because метро is an indeclinable noun.

That means it stays the same in different cases:

• метро
• в метро
• из метро
• к метро

This happens with a number of loanwords in Russian, especially some nouns ending in -о.

Even though the form does not change, the case is still understood from the preposition and the sentence structure. Here, after в meaning location, it is functioning as prepositional.

It can mean either one, depending on context.

Russian present tense often covers both:

• what is happening now
• what usually happens

So Я почти не слышу музыку в метро could mean:

• Right now, in this metro carriage, I can barely hear the music
• In general, I can barely hear music in the metro

If the speaker wants to make the habitual meaning more explicit, they could add words like:

• обычно = usually
• часто = often

For example:

• Я обычно почти не слышу музыку в метро

Russian has no articles, so there is no direct equivalent of a/an/the.

That means музыку can be understood in different ways depending on context:

• music
• the music
• sometimes some music

In this sentence, English could be translated in several ways:

• I can barely hear music in the metro
• I can barely hear the music in the metro

The surrounding context tells you which meaning is intended. Russian speakers rely on context much more than English speakers do for this.

Yes. Russian word order is flexible, and changing it changes emphasis more than basic meaning.

Neutral order:

• Я почти не слышу музыку в метро.

Other possible orders:

• В метро я почти не слышу музыку.
  emphasis on in the metro
• Музыку я почти не слышу в метро.
  emphasis on music
• Я музыку в метро почти не слышу.
  also possible, with a slightly different rhythm or focus

So the original sentence is natural, but not the only possible order.