Questions & Answers about Тихая музыка звучит в кафе как фон.
Тихая is an adjective that must agree with музыка in gender, number, and case.
- музыка is:
- feminine
- singular
- in the nominative case (it is the subject of the sentence)
The basic adjective тихий (quiet) declines like this in the nominative:
- masculine: тихий
- feminine: тихая
- neuter: тихое
- plural: тихие
So the correct form to match музыка (fem. sing. nom.) is тихая.
Other forms like тихой are used in other cases (genitive, dative, instrumental, prepositional) or after some prepositions, but not for a simple subject in the nominative here.
Тихо is an adverb (“quietly”), not an adjective, so it can’t directly modify музыка; it would modify the verb:
- Музыка звучит тихо. – The music sounds quiet(ly).
Музыка here is the grammatical subject of the sentence, so it must be in the nominative case.
- Тихая музыка – subject (nominative)
- звучит – verb (3rd person singular)
- в кафе как фон – adverbial part (where and how)
The verb звучать (to sound) is intransitive in this sentence: it does not take a direct object. So we do put into the accusative (); that would only happen if it were a direct object of some verb.