kyonen yori zuibun nihongo ga kikitoreru you ni natte, zibun demo odoroite iru.

去年より means than last year or compared with last year.

Here, より is the comparison particle. The sentence is comparing the speaker’s current Japanese listening ability with their ability last year.

A useful point: Japanese often leaves the other side of the comparison unstated when it is obvious. So 去年より really means something like more than I could last year.

ずいぶん is an adverb meaning considerably, quite a lot, or far more than before.

So 去年よりずいぶん日本語が聞き取れる gives the feeling of:

• I can understand spoken Japanese much better than last year
• there has been a noticeable improvement

It is stronger than just saying 少し (a little).

This is a very common question.

With potential expressions like 聞き取れる (can catch / can make out / can understand by hearing), Japanese often marks the thing that can be done with が rather than を.

So:

• 日本語が聞き取れる = I can make out Japanese / I can understand spoken Japanese

Using を is sometimes possible in real-life Japanese with some potential forms, but が is the standard and very common choice here.

These are easy to mix up.

• 聞く = to listen / to hear intentionally
• 聞こえる = to be audible / to be heard
• 聞き取れる = to catch what is being said / to make out / to understand by listening

So 日本語が聞き取れる does not just mean I can hear Japanese sounds. It means I can actually catch and understand what is being said.

That nuance is important in this sentence.

Verb + ようになる means to come to be able to..., to reach the point where..., or more generally to undergo a change so that...

So:

• 聞き取れるようになる = to become able to understand/catch it by listening

This pattern emphasizes change over time.

In this sentence, the speaker is saying that compared with last year, they have reached a new level where they can understand spoken Japanese much better.

Because the sentence is talking about ability, not habit.

Compare:

• 聞き取れるようになる = become able to catch/understand
• 聞き取るようになる = come to do it habitually / start doing it

In this sentence, the idea is clearly I can now understand spoken Japanese better, so the potential form 聞き取れる is the natural choice.

The て-form connects this clause to the next one.

So:

• 聞き取れるようになって、自分でも驚いている
• I’ve become able to understand spoken Japanese much better, and even I’m surprised

The て-form here works like and, but it also suggests a natural flow:
because this change happened, I’m surprised myself.

Here, 自分 means oneself / myself, and でも adds the nuance of even.

So 自分でも驚いている means:

• Even I am surprised
• I myself am surprised too
• I’m surprised, even from my own perspective

The speaker is saying the improvement is big enough that they themselves find it surprising.

Important: this でも is not the but meaning. It is the particle meaning even.

驚いている describes the speaker’s current state of being surprised.

So the nuance is:

• 驚いた = I was surprised / a completed reaction
• 驚いている = I am surprised / I’m in a surprised state now

In this sentence, the speaker is looking at their present improvement and saying that they are still surprised by it now, so 驚いている fits very well.

The subject is understood from context as I.

Japanese often omits subjects when they are obvious. In this sentence, the clues are:

• 自分でも = even I myself
• the overall content is about someone’s own progress

So the natural interpretation is:

• I can understand spoken Japanese much better than last year, and even I’m surprised.

This kind of omission is extremely normal in Japanese.

It implies a comparison between last year and now.

Japanese often states only the reference point:

• 去年より = than last year

The unstated idea is:

• now, compared with last year

So the sentence is not floating in time. It strongly suggests the speaker is talking about their current ability.

Yes. 去年よりも is also natural.

The difference is small:

• より = neutral comparison
• よりも = slightly more emphatic

So:

• 去年よりずいぶん...
• 去年よりもずいぶん...

Both work. The version in the sentence is completely natural and a little more straightforward.

This sentence is in plain style:

• なって
• 驚いている

It sounds natural in casual writing, conversation, diaries, essays, social media, and many non-polite contexts.

A polite version could be something like:

• 去年よりずいぶん日本語が聞き取れるようになって、自分でも驚いています。

So the grammar is not rude; it is just non-polite/plain.

The comma helps separate the two parts of the sentence and makes it easier to read:

• 去年よりずいぶん日本語が聞き取れるようになって、
• 自分でも驚いている。

It marks a pause after the first idea and before the speaker’s reaction.

Japanese commas are somewhat flexible, so this comma is mainly there for clarity and rhythm.