Mi hermana suele tararear lo que oye en esa emisora por la mañana, y yo también termino tarareando la melodía.

Soler + infinitive is a very common way to say that someone usually or tends to do something.

So:

• Mi hermana suele tararear... = My sister usually hums... / My sister tends to hum...

A few useful points:

• Soler is almost always followed by an infinitive.
• It talks about habit, not a single action.
• It is more natural in Spanish than always using an adverb like usualmente.

Examples:

• Suelo leer por la noche. = I usually read at night.
• Suelen llegar tarde. = They usually arrive late.

Here lo que means what or that which.

So:

• lo que oye = what she hears

Why lo?

• Lo is a neuter article/pronoun here.
• It does not mean it in this sentence.
• It turns que into a phrase meaning the thing that or what.

Compare:

• Lo que dices = what you say
• Lo que veo = what I see
• No entiendo lo que quiere. = I do not understand what he/she wants.

So tararear lo que oye literally means to hum what she hears.

Both oír and escuchar relate to hearing, but they are not always used in exactly the same way.

In this sentence:

• oír = to hear
• escuchar = to listen to

So:

• lo que oye focuses on what reaches her ears
• lo que escucha would sound more like what she listens to

Because the sentence is about her humming whatever comes from that radio station, oye works very naturally.

Compare:

• Oigo un ruido. = I hear a noise.
• Escucho la radio. = I listen to the radio.

That said, in real life there can be overlap, and sometimes both verbs are possible depending on the nuance.

Emisora means radio station.

So:

• esa emisora = that radio station

This is more specific than radio, which can mean:

• the device itself
• radio as a medium
• sometimes a station, depending on context

In Spain, emisora is a very normal word for a broadcasting station.

Examples:

• Esa emisora pone buena música. = That station plays good music.
• Escucho la radio todos los días. = I listen to the radio every day.

Esa is a demonstrative adjective meaning that.

Spanish has a three-way contrast:

• esta = this
• esa = that
• aquella = that over there / that one farther away

Here esa emisora means that station, probably one already known from the context.

Also note:

• emisora is feminine singular
• so the demonstrative must match: esa

Examples:

• esta canción = this song
• esa emisora = that station
• aquella ciudad = that city over there

In Spain, por la mañana is the normal way to say in the morning.

Similarly:

• por la tarde = in the afternoon
• por la noche = at night / in the evening

So:

• en esa emisora por la mañana = on that station in the morning

For an English speaker, this is just one of those expressions that should be learned as a set phrase.

Examples:

• Trabajo por la mañana. = I work in the morning.
• Estudio por la tarde. = I study in the afternoon.
• Salimos por la noche. = We go out at night.

Yes, Spanish could leave out yo:

• ...y también termino tarareando la melodía.

That would still be correct.

The subject pronoun yo is included here for emphasis or contrast. It helps express:

• and I also...
• my sister does it, and I end up doing it too

Spanish often omits subject pronouns because the verb ending already shows the subject, but speakers include them when they want to highlight the person.

So:

• yo is not required for grammar
• it is used for focus

Because y and también do different jobs.

• y = and
• también = also / too

So:

• y yo también... = and I also...

Without también, the idea of too would be weaker or disappear.

Compare:

• Mi hermana canta y yo bailo. = My sister sings and I dance.
• Mi hermana canta y yo también canto. = My sister sings and I sing too.

These are two different structures with different meanings.

1. terminar + gerundio

This means to end up doing something.

• termino tarareando la melodía = I end up humming the melody

It suggests an unplanned result.

2. terminar de + infinitive

This means to finish doing something or sometimes to have just done something.

• termino de tararear la melodía = I finish humming the melody
• acabo de tararear la melodía = I have just hummed the melody

So in your sentence, termino tarareando is the right choice because the idea is:

• I eventually find myself humming it too

Because after terminar in this meaning, Spanish uses a gerund to express the action someone ends up doing.

Structure:

• terminar + gerundio

Examples:

• Terminó llorando. = He/She ended up crying.
• Terminé comprándolo. = I ended up buying it.
• Acabaron viviendo en Madrid. = They ended up living in Madrid.

So:

• termino tarareando = I end up humming

This is not the same as the English continuous tense. Here the gerund is part of a fixed verbal pattern.

Spanish often uses the definite article where English might not.

Here la melodía means:

• the melody

It refers to the melody that has just been implied by the music she hears and hums. In other words, it is a specific melody understood from the context.

Spanish uses articles very naturally in cases like this:

• Me duele la cabeza. = My head hurts.
• Tocó la guitarra. = He/She played the guitar.
• Tarareé la canción. = I hummed the song.

So la melodía sounds more natural than leaving the article out.

No. Tararear means to hum, while cantar means to sing.

So:

• cantar = use the lyrics/words, or sing musically
• tararear = make the tune with your voice, often without words

Examples:

• Cantó la canción completa. = He/She sang the whole song.
• Tarareó la melodía. = He/She hummed the melody.

In your sentence, tararear is perfect because the focus is on the tune getting stuck in someone's head.

Oye is the third-person singular present form of oír.

Conjugation of oír in the present:

• oigo = I hear
• oyes = you hear
• oye = he/she hears
• oímos = we hear
• oís = you all hear
• oyen = they hear

So:

• lo que oye = what she hears

This verb is a bit irregular, so it is worth memorizing.

It most naturally modifies the idea of hearing things on that station in the morning.

So the phrase means roughly:

• My sister usually hums what she hears on that station in the morning...

In other words, por la mañana tells you when this happens.

Spanish often places time expressions after the main information, and that word order sounds natural here.

In many contexts, acabar + gerundio and terminar + gerundio can both mean to end up doing something.

So:

• termino tarareando la melodía
• acabo tarareando la melodía

Both can work.

Still, there can be slight stylistic differences depending on region and speaker:

• terminar + gerundio often sounds very straightforward
• acabar + gerundio is also very common and can feel slightly more idiomatic in some contexts

In this sentence, termino tarareando is completely natural.

No, not really. Repeating tararear is natural because both parts of the sentence describe the same action done by two different people:

• Mi hermana suele tararear...
• yo también termino tarareando...

This repetition actually helps connect the two ideas clearly:

1. your sister hums what she hears
2. as a result, you end up humming the tune too

Spanish often repeats a verb when that is the clearest and most natural way to express the idea.