Learn Hardcore Finnish: Hänen äänensä on rauhallinen.

Finnish can mark possession directly on the noun with a possessive suffix. For 3rd person singular (“his/her”), that suffix is -nsA (-nsa / -nsä depending on vowel harmony).

So:

ääni (voice)
ääni + nsä → äänensä = his/her voice

In this sentence:

Hänen = his/her (genitive pronoun)
äänensä = (his/her) voice (with possessive suffix)
Together: Hänen äänensä = “his/her voice”

Why do we have both hänen and the possessive ending -nsä? Isn’t one of them enough?

You’ve spotted a classic “double marking” feature of standard Finnish.

Standard / formal written Finnish usually prefers:
- hänen äänensä = his/her voice
  (genitive pronoun + possessive suffix)
Colloquial / everyday Finnish often uses just the genitive pronoun:
- hänen ääni = his/her voice (no suffix)
Or, in more formal style but without the pronoun, you can use only the suffix:
- hänen äänensä
- or just äänensä if it’s clear whose voice you’re talking about from context (this is more literary/poetic).

So:

Hänen äänensä on rauhallinen. – very standard, textbook style.
Hänen ääni on rauhallinen. – common in speech and informal writing.

Both are understandable; the first is the most “correct” in traditional grammar.

Is äänensä in the nominative or some other case? Why doesn’t it look like plain ääni?

Grammatically, äänensä here is the subject of the sentence, so it’s in the nominative case (the basic case).

What makes it look different from plain ääni is:

The stem change of the noun ääni
- Nominative: ääni
- Stem: ääne- (seen in forms like äänen, äänessä, etc.)
Addition of the possessive suffix -nsä to the stem:
- ääne- + nsä → äänensä

You don’t need to worry about all the historical details; the key takeaway:

ääni
- possessive suffix → äänensä
Even though the form changes, its grammatical case here is still nominative (it’s the subject).

Why is there no word for “the” or “a” in this sentence?

Finnish simply doesn’t have articles like “a/an” or “the”.

Hänen äänensä can mean:
- “his/her voice”
- “the voice of his/hers”
- “that voice of his/hers”
Context tells you whether the meaning is definite or indefinite. In this specific sentence, English naturally uses “his/her voice” (definite), but nothing in the Finnish explicitly marks definiteness.

So:

No separate words for a / an / the.
The same Finnish phrase can correspond to several different English article choices.

What does rauhallinen really mean here? Is it “calm”, “peaceful”, “quiet”…?

Rauhallinen is an adjective derived from:

rauha = peace
-llinen = a common suffix that forms adjectives

So rauhallinen is roughly:

peaceful, calm, tranquil, unhurried

When applied to a voice, rauhallinen ääni usually suggests:

soothing, steady, not agitated
speaking calmly, without stress or hurry

Contrast with some related adjectives:

hiljainen ääni – quiet voice (low volume)
tasainen ääni – even / steady voice (no big changes in tone)
pehmeä ääni – soft voice (gentle sound quality)

So in “Hänen äänensä on rauhallinen”, a natural translation is “His/Her voice is calm/soothing.”

Why is it rauhallinen and not rauhallista?

In Finnish, after olla (“to be”), the describing word (predicate adjective) is usually in the nominative when we talk about a normal, complete quality:

Hänen äänensä on rauhallinen.
= His/Her voice is calm.
(calm is a straightforward property of the whole voice)

The partitive form (rauhallista) is used in special, more nuanced cases, often when:

the state is incomplete, changing, or only partly true, or
you’re focusing on the amount/degree of a quality.

For a voice, “Hänen äänensä on rauhallista” would sound unusual in most contexts and might be interpreted as something like:

“His/her voice is somewhat calm-ish” / “(There is) calmness in his/her voice.”

In normal, neutral description of a stable trait, nominative is correct:

rauhallinen

How is on formed, and why is that the right form of the verb “to be” here?

The infinitive is:

olla = to be

The present tense forms are:

(minä) olen – I am
(sinä) olet – you are
(hän/se) on – he/she/it is
(me) olemme – we are
(te) olette – you (pl) are
(he/ne) ovat – they are

The subject in the sentence is Hänen äänensä = “his/her voice” → third person singular.
So we use the 3rd person singular form:

on = “is”

If it were plural, you’d change the verb:

Heidän äänensä ovat rauhallisia.
“Their voices are calm.”

Could I change the word order, like “Rauhallinen on hänen äänensä”?

Yes, Finnish word order is flexible, and you can move elements to change emphasis, not basic meaning.

Neutral / most common:
- Hänen äänensä on rauhallinen.
  → neutral statement: “His/Her voice is calm.”
Emphasizing the calmness:
- Rauhallinen on hänen äänensä.
  → more like: “Calm is his/her voice” / “It’s calm, that voice of his/hers.”
  This is stylistic, poetic, or contrastive.
Dropping the pronoun but keeping the suffix (more literary):
- Äänensä on rauhallinen.
  → “His/her voice is calm” (assuming context makes it clear whose).

All are grammatically possible; the version you were given is the neutral, textbook-like order.

How do you pronounce “Hänen äänensä on rauhallinen”?

Key pronunciation points:

Stress is always on the first syllable of each word:
- HÄ-nen ÄÄ-nen-sä on RAU-hal-li-nen
ä is like the a in English “cat” (but a bit clearer and tenser).
ää is a long version of that sound: hold it about twice as long.
au in rauha- is like English “ow” in “now”, but smoother.
Double ll in rauhallinen is a long consonant: hold the l slightly longer.

Approximate syllable breakdown:

Hä-nen ää-nen-sä on rau-hal-li-nen

If you keep the vowel lengths (short vs long) and the first-syllable stress, you’ll already sound much closer to natural Finnish.

Does hän mean “he” or “she”? How do I know which one this sentence refers to?

Hän is gender-neutral:

hän = he / she
hänen = his / her

Finnish does not grammatically distinguish male vs female pronouns. So:

Hänen äänensä on rauhallinen.
could mean:
- “His voice is calm.”
  or
- “Her voice is calm.”

You know which one is intended only from context (who you’re talking about). If you really need to specify, you usually mention the person:

Tytön ääni on rauhallinen. – The girl’s voice is calm.
Miehen ääni on rauhallinen. – The man’s voice is calm.