Learn Hardcore Finnish: Päivän hälinä unohtuu, kun istumme sohvalle juttelemaan läheisten kanssa. - The day’s bustle is forgotten when we sit on the sofa to chat with our loved ones.

Hälinä is “hubbub, bustle, noisy activity” – it often suggests a mixture of noise + movement + busyness (people talking, moving around, things happening).

Melu is more neutral “noise” or “loud sound”, and doesn’t necessarily imply busyness. Examples:

liikenteen melu – traffic noise (just sound)
torin hälinä – the bustle/hubbub of the market (people, movement, sound together)

In the sentence, päivän hälinä is “the day’s hustle and bustle”, not just literal loud noise.

Why is unohtuu (from unohtua) used instead of unohdamme or unohdetaan?

There are two different verbs:

unohtaa = to forget (transitive: someone forgets something)
- unohdamme hälinän – “we forget the bustle”
unohtua = to be forgotten, to fade from one’s mind (intransitive: something gets forgotten, often “by itself”)
- hälinä unohtuu – “the bustle is (gets) forgotten / fades away”

In the sentence, the idea is that the day’s hustle and bustle naturally fades away when we sit on the sofa; no one is actively, deliberately “forgetting” it. That’s why unohtua is used:

Päivän hälinä unohtuu... = “The day’s bustle just fades from our mind...”

Is unohtuu a passive form?

No.

Unohtuu is:

3rd person singular, present tense
of the intransitive verb unohtua

Finnish passive (also called “impersonal”) for “forget” would be:

unohdetaan – “(people) forget”, “one forgets”

So:

hälinä unohtuu – “the bustle is forgotten / fades away” (it happens to it)
hälinä unohdetaan – “the bustle is forgotten (by people)” (impersonal passive of unohtaa)

The sentence uses unohtuu to sound more natural and less agent-focused.

Why is there a comma before kun?

In Finnish, you normally put a comma between a main clause and a subordinate clause, even if the order is main → subordinate (unlike English, which often omits it).

Päivän hälinä unohtuu, kun istumme sohvalle juttelemaan...
Main clause: Päivän hälinä unohtuu
Subordinate clause: kun istumme sohvalle juttelemaan...

If you reverse the order, you still use a comma:

Kun istumme sohvalle juttelemaan läheisten kanssa, päivän hälinä unohtuu.

What is the role of kun here, and how is it different from milloin?

Here kun is a subordinating conjunction meaning “when” in the sense of “at the time that / whenever”.

kun istumme sohvalle – “when(ever) we sit down on the sofa”

Milloin is a question word:

Milloin istutte sohvalle? – “When do you (pl.) sit on the sofa?”

You don’t use milloin to introduce a normal “when”-clause like this; you use kun.

Why is it istumme sohvalle and not istumme sohvalla?

This is a case difference:

sohvalle – allative: “onto the sofa / to the sofa” (movement towards/onto a surface)
sohvalla – adessive: “on the sofa” (location on a surface, staying there)

Istua + allative expresses the act of sitting down (onto something):

istua tuolille – to sit down on a chair
istua lattialle – to sit down on the floor
istua sohvalle – to sit down on the sofa

So istumme sohvalle is “we sit down on the sofa”, focusing on the movement.

If you said istumme sohvalla, it would mean “we (are) sit(ting) on the sofa”, more about the state of already being seated, not the act of sitting down.

Why is juttelemaan used instead of the basic form jutella?

Juttelemaan is the 3rd infinitive, illative form of jutella (to chat).

The pattern is:

verb of movement/position + -maan / -mään form
→ expresses purpose (“in order to do X”)

So:

istua sohvalle juttelemaan
literally: “to sit onto the sofa to-chat”
= “to sit down on the sofa in order to chat”

Using just istumme sohvalle jutella is ungrammatical in standard Finnish. For purpose after verbs like mennä, tulla, jäädä, istua etc., you use this -maan / -mään form:

mennä nukkumaan – go to sleep
tulla syömään – come to eat
jäädä juttelemaan – stay to chat
istua sohvalle juttelemaan – sit down on the sofa to chat

Is istua + (place) + juttelemaan a fixed expression, or part of a broader pattern?

It’s part of a broader pattern:

[verb of movement/position] + [place (often illative/allative)] + [3rd infinitive in -maan / -mään]

This pattern expresses going/coming/sitting/etc. somewhere in order to do something:

mennä kirjastoon lukemaan – go to the library to read
tulla meille syömään – come to our place to eat
jäädä kotiin lepäämään – stay home to rest
istua pöydän ääreen syömään – sit down at the table to eat
istua sohvalle juttelemaan – sit down on the sofa to chat

So istua sohvalle juttelemaan fits this general “purpose of movement/position” construction.

What does läheisten literally mean, and why is it in that form?

The base word is läheinen:

as an adjective: “close, near”
as a noun: “a close person, loved one, close relative/friend”

Läheiset (nominative plural) ≈ “close ones / loved ones”.
Läheisten is the genitive plural, “of (the) close ones / of loved ones”.

Here it appears before kanssa, which requires the genitive:

läheisten kanssa – “with (our/the) loved ones”
structurally: “with the close ones”

Why does kanssa require the genitive case?

Kanssa is a postposition meaning “with”, and it regularly takes the genitive:

ystävä → ystävän kanssa – with a friend
lapset → lasten kanssa – with (the) children
läheiset → läheisten kanssa – with loved ones

So läheisten is in the genitive plural because kanssa almost always appears as:

[genitive noun/pronoun] + kanssa

Could we say kun me istumme sohvalle instead of kun istumme sohvalle? Does it change the meaning?

Yes, you can say kun me istumme sohvalle, and it is grammatically correct.

In Finnish, subject pronouns (minä, sinä, me, te, etc.) are often omitted, because the verb ending already shows the person and number:

istumme already means “we sit / we are sitting”

Adding me usually:

adds a bit of emphasis on “we” (as opposed to someone else), or
makes the style slightly more spoken/informal or explicit.

So:

kun istumme sohvalle – neutral “when we sit down on the sofa”
kun me istumme sohvalle – “when we sit down on the sofa” (slight emphasis on we)