Learn Hardcore Spanish (Spain): La música calma a mi hermano cuando tiene miedo. - Music calms my brother when he is afraid.

Leaving out the article (Música calma a mi hermano) sounds wrong in standard Spanish. The article is normally required with abstract nouns and things in general:

La comida es cara. = Food is expensive.
El amor es difícil. = Love is difficult.

So la música is the normal way to say music in this kind of general statement.

Why is calma used here, and what form is it?

Calma is the third person singular of the verb calmar in the present indicative:

Yo calmo
Tú calmas
Él / Ella / Usted calma
Nosotros calmamos
Vosotros calmáis
Ellos / Ustedes calman

The subject is la música, which is third person singular, so the verb agrees with it:

La música calma… = Music calms…

It’s a transitive verb here: calmar (to calm) something/someone. In this sentence, what it calms is a mi hermano.

Why do we say a mi hermano and not just mi hermano after calma?

Spanish uses the personal a before direct objects that are:

specific people
pets (often)
or person-like entities

Here, mi hermano is a specific person, so you need a:

La música calma a mi hermano. ✅
La música calma mi hermano. ❌ (wrong in standard Spanish)

More examples:

Veo a María. = I see María.
Llamo a mi madre. = I call my mother.

So a mi hermano is just my brother (as a direct object), with the necessary personal a.

Could you say La música lo calma cuando tiene miedo instead? What’s the difference?

Yes, you can say:

La música lo calma cuando tiene miedo.

Here, lo is a direct object pronoun meaning him, and it replaces a mi hermano. Both are correct:

La música calma a mi hermano cuando tiene miedo.
La música lo calma cuando tiene miedo.

You wouldn’t normally use both together (La música lo calma a mi hermano) unless you’re doing it for emphasis in certain dialects; in standard usage, pick one or the other.

Why is it tiene miedo and not something like es miedoso or está asustado?

All exist, but they’re not exactly the same:

Tiene miedo = he is afraid, literally he has fear.
- Focuses on the feeling of fear at that moment.
Está asustado = he is scared.
- Very close in meaning; describes a current state of being frightened.
Es miedoso = he is fearful / a scaredy-cat (by character).
- Describes a personality trait, not just a temporary feeling.

In your sentence, tiene miedo expresses whenever he is afraid (temporarily), which matches the idea of music calming him in those moments.

Why is there no él in cuando tiene miedo? Why not cuando él tiene miedo?

Spanish is a “pro‑drop” language: subject pronouns (yo, tú, él, etc.) are often omitted because the verb form usually makes the subject clear.

Cuando tiene miedo…
Context tells us we’re still talking about mi hermano, so we don’t need él.

You can say:

La música calma a mi hermano cuando él tiene miedo.

But adding él usually adds a nuance of contrast or emphasis, e.g. specifically when he is afraid (and not someone else). In neutral, everyday speech, the version without él is more natural.

What kind of present tense is calma here? Does it mean “right now” or a general truth?

In Spanish, the simple present can mean:

Habitual/general action
- La música calma a mi hermano cuando tiene miedo.
  = Music calms my brother when he is afraid (whenever that happens).
Right now
- Ahora la música lo calma. = Right now, music is calming him.

Here it clearly expresses a general or habitual fact about your brother: whenever he is afraid, music (in general) calms him.

Can I change the word order to Cuando tiene miedo, la música calma a mi hermano?

Yes, that’s perfectly correct:

La música calma a mi hermano cuando tiene miedo.
Cuando tiene miedo, la música calma a mi hermano.

Both sound natural in Spain. Putting cuando tiene miedo at the beginning just emphasizes the condition/time first. The meaning is the same.

Why is it mi hermano and not mí hermano? What’s the difference between mi and mí?

mi (without accent) = my (possessive adjective)
- mi hermano = my brother
- mi casa = my house
mí (with accent) = me (stressed object pronoun, after prepositions)
- para mí = for me
- sin mí = without me

In your sentence it’s a possessive: my brother, so it must be mi hermano (no accent).

Why does música have an accent? How do I know when to write it?

Música has an accent because of Spanish stress rules:

Words ending in a vowel, -n, or -s are normally stressed on the second‑to‑last syllable.
música is pronounced MÚ-si-ca (stress on the first syllable), which breaks that rule.
To show this irregular stress, Spanish writes an accent mark: música.

Other similar examples:

lápiz (LA‑piz)
teléfono (te‑LÉ‑fo‑no)

The accent mark only affects pronunciation/stress, not the basic meaning.

Could I say La música tranquiliza a mi hermano instead of calma?

Yes, but there is a small nuance:

calmar = to calm, to soothe
tranquilizar = to make (someone) calm/quiet, to reassure

Both verbs can work. Calmar is slightly more general and very common in this context. Tranquilizar can sound a bit more like reassuring or settling someone down, but in many contexts they’re almost interchangeable:

La música calma a mi hermano.
La música tranquiliza a mi hermano.

Both are fine in Spanish from Spain.

If I want to say “Music calms me when I am afraid”, how do I change the sentence?

You mainly change a mi hermano to a first-person object:

Option 1: with a pronoun

La música me calma cuando tengo miedo.

Option 2: with an explicit noun phrase

La música calma a mi cuando tengo miedo. ❌ (wrong: needs accent and pronoun)
Correct: La música me calma a mí cuando tengo miedo.
(Here a mí adds emphasis: me in particular.)

The normal and most common version is:

La música me calma cuando tengo miedo.