Learn Turkish: Biz müzik dinliyorken yaya aniden caddeye çıktı. - The pedestrian suddenly stepped into the street while we were listening to music.

The suffix -ken means 'while'. When added to the present continuous -iyor, it describes an ongoing background action: dinliyorken (while listening). Notice that -ken never takes personal endings. Because of this, we must include the pronoun Biz at the beginning so we know 'we' were listening, and not the pedestrian.

Why doesn't the suffix -ken change to match the vowels in dinliyor?

The suffix -ken is one of the rare Turkish suffixes that completely ignores vowel harmony. It is always -ken, never '-kan', which is why it looks a bit unusual attached to the back vowels of -iyor as -iyorken.

Why does cadde have the ending -ye in this sentence?

The pedestrian is moving into or out onto the street, so we need the dative case to show direction towards a place. We take cadde (street), add the buffer letter y to separate the vowels, and add e to make caddeye (to/into the street).

Why is the verb çıkmak used for 'stepped into'?