Learn Hardcore Finnish: Olen innostunut opiskelemaan lisää, kun huomaan, että ääntäminen paranee. - I am excited to study more when I notice that my pronunciation is improving.

Innostunut is the past participle of innostua (to get excited, to become enthusiastic). In this sentence it works like an adjective: excited / enthusiastic.

So olen innostunut is literally I am excited / I have become enthusiastic.
Grammatically it is:

olen – verb olla, present tense
innostunut – past participle used as a predicative adjective

It does not mean a perfect tense like I have studied; it is more like I am (in a state of) excited.

Why is it opiskelemaan and not opiskella after olen innostunut?

Opiskelemaan is the so‑called third infinitive illative of opiskella (to study).

Basic infinitive: opiskella
Third infinitive stem: opiskelema‑
Illative ending: ‑an
→ opiskelemaan

After many verbs and adjectives that express interest, enthusiasm, beginning, readiness, going somewhere to do something, Finnish uses this ‑maan / ‑mään form:

Olen innostunut opiskelemaan. – I am excited about studying.
Alan opiskelemaan. – I am starting to study.
Menen opiskelemaan. – I go to study.

Opiskella here would be wrong or at least sound foreign; a native expects innostunut opiskelemaan, not innostunut opiskella.

What does lisää mean here, and how is it different from enemmän?

Both lisää and enemmän can correspond to more in English, but they are used a bit differently.

Lisää focuses on an additional amount of something:
- opiskelemaan lisää – to study more / additionally / some extra
Enemmän focuses on a larger quantity or comparison:
- opiskelemaan enemmän – to study more (than before / than someone else)

In this sentence:

opiskelemaan lisää suggests: I am excited to keep studying, to add more studying, without necessarily comparing to anything.
opiskelemaan enemmän would put a bit more emphasis on increasing the amount compared to some baseline (e.g. more than before).

Both can be used, but lisää fits very naturally for more (extra).

Why is there a comma before kun?

In Finnish, a comma is normally placed between a main clause and a subordinate clause.

Here:

Main clause: Olen innostunut opiskelemaan lisää
Subordinate clause: kun huomaan, että ääntäminen paranee

Because kun introduces a subordinate clause (kun huomaan, että ääntäminen paranee), there is a comma before it:

Olen innostunut opiskelemaan lisää, kun huomaan, että ääntäminen paranee.

You would also put a comma if the kun‑clause came first:

Kun huomaan, että ääntäminen paranee, olen innostunut opiskelemaan lisää.

What does kun mean here? Is it “when” or “because”?

Kun can mean both when and because, depending on context.

In this sentence, both readings are actually possible:

Temporal “when”
- I get excited about studying more *when I notice that my pronunciation is improving.*
Causal “because”
- I get excited about studying more *because I notice that my pronunciation is improving.*

Many native speakers would feel that both nuances are present: the time relationship (when) and the cause (because). English usually has to choose one, but Finnish kun can cover both in such sentences.

What is the role of että in että ääntäminen paranee, and can you leave it out?

Että is a conjunction meaning that, introducing a content clause (a reported thought, feeling, perception, etc.).

Structure:

huomaan – I notice
että ääntäminen paranee – that the pronunciation is improving

In Finnish you must keep että here. Unlike in English, you generally cannot drop the that:

Natural Finnish: huomaan, että ääntäminen paranee
Ungrammatical/very wrong: huomaan ääntäminen paranee

So että marks that what follows is the content of what you notice.

What is ääntäminen, and how is it formed from a verb?

Ääntäminen is a noun, meaning pronunciation.

It is built from the verb ääntää (to pronounce) using the ‑minen ending:

verb: ääntää – to pronounce
verbal noun: ääntäminen – pronunciation

This ‑minen form is very common in Finnish. Examples:

opiskella → opiskeleminen – studying
kirjoittaa → kirjoittaminen – writing
puhua → puhuminen – speaking

So ääntäminen paranee literally is the pronunciation gets better / the pronunciation improves.

Why is ääntäminen in the basic form (nominative), not in some case like ääntämistä?

In this sentence ääntäminen is the subject of the verb paranee:

ääntäminen – subject
paranee – verb

Subjects in Finnish are normally in the nominative case (the dictionary form), so ääntäminen is nominative.

If ääntäminen were an object of some other verb, you might see other cases like partitive (ääntämistä) or accusative. But here it is simply the thing that improves, so nominative is correct.

What does paranee mean exactly, and why this form?

Paranee is the 3rd person singular present of the verb parantua / parantua/parata (to get better, to improve, to heal).

Verb: parantua / parata – to improve, to get better
3rd person singular present: paranee – gets better / is improving

In the sentence:

ääntäminen – pronunciation (3rd person singular subject)
paranee – improves

So ääntäminen paranee means the pronunciation improves / is improving.

You could also, in other contexts, use a perfect tense:

ääntäminen on parantunut – the pronunciation has improved (result is now visible)

But here, paranee presents it as a repeated, ongoing process: every time you study, you notice that pronunciation is (generally) improving.

What is the difference between parantaa and paranee? Why not use parantaa here?

The difference is about who/what is doing the improving:

parantaa – to improve something, to make something better (transitive)
- Harjoittelu parantaa ääntämistä. – Practice improves pronunciation.
paranee (from parantua / parata) – to get better by itself (intransitive)
- Ääntäminen paranee. – Pronunciation gets better.

In your sentence, ääntäminen itself is what is changing, so we use the intransitive form:

ääntäminen paranee – pronunciation improves (by itself, as a result of your studying)

Could you also say Olen innostunut opiskelemaan enemmän? How would that differ from lisää?

Yes, Olen innostunut opiskelemaan enemmän is grammatically fine.

Nuance:

opiskelemaan lisää – to study more in the sense of extra, additionally, without explicit comparison
opiskelemaan enemmän – to study more compared to some reference (than before, than others, etc.)

In practice:

If you mean I’m excited to keep studying, to do more of it, lisää is very natural.
If you want to stress increasing the amount relative to before (e.g. “I used to study 10 minutes a day, now I want to study 30”), enemmän highlights that comparison a bit more.

Can the word order be Kun huomaan, että ääntäminen paranee, olen innostunut opiskelemaan lisää? Does that change the meaning?

Yes, that word order is completely correct:

Kun huomaan, että ääntäminen paranee, olen innostunut opiskelemaan lisää.

The meaning stays essentially the same. The difference is mostly about emphasis and flow:

Olen innostunut opiskelemaan lisää, kun huomaan, että ääntäminen paranee.
Starts by stating that you are excited to study more, then gives the condition/reason.
Kun huomaan, että ääntäminen paranee, olen innostunut opiskelemaan lisää.
Starts by describing the situation (when you notice improvement), then states the reaction.

Both orders are natural Finnish. The choice mainly depends on what you want to introduce first in the sentence.