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"Escuchar música" is an intransitive verb phrase which is often translated as "to listen to music", and "ir a una fiesta" is an intransitive verb phrase which is often translated as "to go to a party". Learn more about the difference between "escuchar música" and "ir a una fiesta" below.
escuchar música( 
ehs
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koo
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chahr
moo
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see
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kah
)An intransitive verb phrase is a phrase that combines a verb with a preposition or other particle and does not require a direct object (e.g., Everybody please stand up.).
1. (general)
a. to listen to music 
En el tren todos van con sus audífonos puestos, escuchando música.Everyone on the train has their headphones on, listening to music.
Las niñas pasaron toda la tarde escuchando música en sus habitaciones.The girls spent all afternoon listening to music in their rooms.
ir a una fiesta(   
eer
ah
oo
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nah
fyehs
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tah
)An intransitive verb phrase is a phrase that combines a verb with a preposition or other particle and does not require a direct object (e.g., Everybody please stand up.).
a. to go to a party 
Mis amigos y yo vamos a una fiesta el viernes por la noche.My friends and I are going to a party on Friday night.
irse a una fiesta
A pronominal verb phrase combines a verb with a preposition or other particle and always uses a reflexive pronoun. (e.g., Se dio cuenta del problema.)
a. to go to a party 
¿Cristina no viene al cine? - No, se fue a una fiesta.Isn't Cristina coming to the movies? - No, she went to a party.