Learn Hardcore Turkish: Gürültüyü sınırlandırmak için kapıyı kapatıyoruz.

In Turkish, definite/specific direct objects take the accusative suffix -(y)ı/-(y)i/-(y)u/-(y)ü, chosen by vowel harmony. The y is a buffer because the nouns end in a vowel.

kapı + yı → kapıyı (the door)
gürültü + yü → gürültüyü (the noise) Without this ending, the object would be indefinite and the sentence would sound odd here.

Why is the object inside the -mek için purpose phrase also accusative: gürültüyü?

Even within an infinitive purpose clause (… -mek için), transitive verbs can take a direct object, and if that object is specific/known or a mass you’re targeting, it’s commonly marked accusative. Here we’re talking about the noise in our environment, so gürültüyü is natural. You might see bare objects in some set expressions (e.g., para kazanmak için), but with gürültü the accusative is standard and sounds better than gürültü azaltmak/sınırlandırmak in everyday speech.

Can I say gürültü azaltmak/sınırlandırmak için instead?

It’s sometimes seen in clipped/technical styles, but in normal speech and writing Turkish strongly prefers the accusative here: gürültüyü azaltmak/sınırlandırmak için. Using the bare gürültü can sound telegraphic or awkward.

What does için mean, and how do I use it?

için means for/for the sake of/in order to.

With nouns: okul için (for school), doktor için (for the doctor)
With pronouns: use genitive forms: benim için (for me), senin için (for you)
With verbs: use the infinitive -mek/-mak: çalışmak için (in order to work), sınırlandırmak için (in order to limit)

Can the … için phrase move around in the sentence?

Yes. Turkish word order is flexible. All of these are fine (most to least typical):

Gürültüyü sınırlandırmak için kapıyı kapatıyoruz.
Kapıyı gürültüyü sınırlandırmak için kapatıyoruz.
Kapıyı kapatıyoruz, gürültüyü sınırlandırmak için. (final position; often with a comma in writing)

How is kapatıyoruz built, and what tense/aspect is it?

kapat- (close) + -ıyor- (present progressive) + -uz (we) → kapatıyoruz = we are closing. The progressive suffix appears as -ıyor/-iyor/-uyor/-üyor by vowel harmony.

Does kapatıyoruz mean right now, or can it be habitual?

Primarily it’s present progressive (right now/around now). For a general or habitual statement, Turkish prefers the aorist:

Habitual: Kapıyı kapatırız (We close the door [as a rule]).
Progressive/current plan: Kapıyı kapatıyoruz (We’re closing the door / we keep closing it).

Is there any difference between kapatmak and kapamak?

They’re near-synonyms meaning to close/shut.

kapatmak is the most common and neutral choice for doors, windows, etc.
kapamak is also correct and a bit more colloquial/older-sounding. Note: the progressive of kapamak is kapıyoruz, which is homophonous with the progressive of kapmak (to grab/snatch). Context disambiguates, but kapatıyoruz avoids that ambiguity.

Could I say something more natural than sınırlandırmak with gürültü?

Yes. Common alternatives:

gürültüyü azaltmak = reduce the noise (very natural)
gürültüyü kısmak = turn down the noise/volume (esp. devices)
gürültüyü kesmek = cut the noise, stop the racket (colloquial)
gürültüyü engellemek/önlemek = block/prevent the noise sınırlamak is also fine and a bit shorter than sınırlandırmak.

Is there a nuance difference between sınırlamak and sınırlandırmak?

They overlap a lot. sınırlamak is shorter and very common; sınırlandırmak often sounds a bit more formal/bureaucratic or emphasizes the act of imposing limits. In this everyday sentence, either works.

Why is there no subject pronoun biz?

Turkish conjugations encode the subject, so the verb ending -uz already tells us we. You add biz only for emphasis/contrast: Biz kapıyı kapatıyoruz (as for us, we’re the ones closing the door).

What’s going on with the letters y in gürültüyü and kapıyı?

It’s a buffer consonant inserted between a vowel-final stem and a vowel-initial suffix. Without it, you’d have a vowel clash. So:

gürültü + -ü → gürültüü (bad) → insert y → gürültüyü
kapı + -ı → kapıı (bad) → insert y → kapıyı

How does vowel harmony affect the accusative endings here?

The accusative chooses its vowel by the last vowel of the noun:

Last vowel is back unrounded (a/ı): use -ı → kapı-yı
Last vowel is front rounded (ö/ü): use -ü → gürültü-yü (Buffer y appears because both stems end in a vowel.)

How would I say this in other tenses or in the negative?

Past: Gürültüyü sınırlandırmak için kapıyı kapattık. (We closed the door…)
Future: … kapatacağız. (We will close…)
Negative: … kapatmıyoruz. (We are not closing…)
Habitual negative: … kapatmayız. (We don’t close…)

How could I express the purpose with diye instead of için?

Use a finite clause with -sın/-sin + diye:

Gürültü azalsın diye kapıyı kapatıyoruz. = We close the door so that the noise will decrease. This is very natural and common in speech.

What if I want to say because of the noise (a reason) rather than a purpose?

Use yüzünden or nedeniyle:

Gürültü yüzünden kapıyı kapatıyoruz.
Gürültü nedeniyle kapıyı kapatıyoruz. These mean we’re closing the door due to the noise, not in order to reduce it.

Is gürültü the same as ses?

No. gürültü is noise (usually unwanted/annoying sound). ses is neutral sound/voice. With this sentence, gürültü is the right word.