asa ha mado wo akeru to, soto no tori no koe ga yoku kikoemasu.

朝は makes morning the topic: as for the morning / in the morning.

A learner might expect 朝に, because に is often used for time, but with broad time words like 朝, 夜, 今日, 明日, Japanese often does not need に.

So:

• 朝は = in the morning, as for mornings
• It also gives a contrastive nuance sometimes, like in the morning (at least)

In this sentence, 朝は sounds very natural because the speaker is setting the scene: In the morning, when I open the window...

Here, Vる + と means when or once something happens.

So:

• 窓を開ける = open the window
• 窓を開けると = when I open the window / once the window is opened

This と is often used when the second part is a natural result, regular outcome, or something that tends to happen automatically.

So the sentence has the feeling of:

• When I open the window in the morning, I can hear the birds outside well.

It is not mainly a deliberate if like a choice or suggestion. It sounds more like a repeated, natural consequence.

Japanese often uses the plain form before grammar patterns like と, から, けど, ので, and many others.

So even though the whole sentence ends politely with 聞こえます, the verb before と stays plain:

• 窓を開けると、外の鳥の声がよく聞こえます。

This is completely normal.

A rough pattern is:

• inside the sentence: plain form
• sentence ending: polite form if the speaker wants polite style

So the mix of 開ける + 聞こえます is standard Japanese.

This is a very common question.

• 聞きます = to listen / to hear in an intentional sense
• 聞こえます = can be heard / is audible / comes into one’s ears naturally

In this sentence, the birds are not something the speaker is actively trying to listen to. Rather, after opening the window, their voices naturally become audible.

So:

• 鳥の声を聞きます would sound more like I listen to the birds
• 鳥の声が聞こえます means I can hear the birds / the birds’ sounds are audible

That is why 聞こえます is the natural choice here.

With 聞こえる, the thing that is heard is usually marked by が, not を.

So:

• 鳥の声が聞こえます = the birds’ voices/sounds are audible

This is because 聞こえる works more like to be heard than to hear something intentionally.

Compare:

• 音楽を聞きます = I listen to music
• 音楽が聞こえます = I can hear music

So が is the normal particle here.

よく can mean different things depending on context:

• often
• well
• clearly

In this sentence, よく聞こえます most naturally means:

• can hear well
• can hear clearly
• can hear easily

So the idea is not mainly I often hear them, but rather their sounds carry well / I can hear them clearly after opening the window.

Context decides the meaning.

Compare:

• その店によく行きます。 = I often go to that shop.
• 小さい声でよく聞こえません。 = I can’t hear well because the voice is quiet.

Here, it is the second type.

This is a noun chain using の.

• 外 = outside
• 外の鳥 = birds outside / outside birds
• 外の鳥の声 = the voices/sounds of the birds outside

So the full phrase means something like:

• the sound of the birds outside
• the birds’ voices from outside

Japanese often stacks nouns this way, and の links them together.

You can think of it step by step:

1. 鳥の声 = birds’ voices / bird sounds
2. 外の鳥の声 = the voices of the birds outside

Japanese usually does not mark singular vs. plural unless it needs to.

So 鳥の声 could mean:

• a bird’s voice
• birds’ voices
• birdsong / bird sounds

In this sentence, English would often translate it naturally as:

• the sound of the birds outside
• the birds outside
• birdsong from outside

So even though 鳥 has no plural ending, the meaning can easily be plural from context.

Japanese often leaves out information that is understood from context.

Here, the person opening the window and hearing the birds is probably the speaker, so Japanese does not need to say 私は.

The sentence naturally implies something like:

• In the morning, when I open the window, I can hear the birds outside well.

If you added 私は, it would still be grammatical, but it may feel unnecessary unless you want contrast or emphasis.

Japanese commonly omits:

• the subject
• the object
• other obvious information

This is one of the biggest differences from English.

Most likely it describes a habitual or general situation.

The non-past form in Japanese often covers:

• present
• future
• repeated habits
• general truths

So this sentence sounds like:

• In the morning, when I open the window, I can hear the birds outside clearly.

That feels like something that usually happens, not just one single event.

If the speaker wanted to emphasize one specific occasion, they would usually give more context or use past forms.

This is a great grammar question.

In this sentence, 開けると suggests a natural, expected result:

• when I open the window, I can hear the birds

It sounds like the second thing happens almost automatically.

If you used たら, the sentence would still be understandable, but the nuance would be a bit different:

• 窓を開けたら、外の鳥の声がよく聞こえます。

That can sound more like when/if I open the window in a more situational sense.

Very roughly:

• と = natural consequence, regular outcome
• たら = when/if, often more flexible and event-based

So と fits nicely here because hearing the birds is the normal result of opening the window.

The comma shows a pause and makes the sentence easier to read.

• 朝は窓を開けると外の鳥の声がよく聞こえます。
• 朝は窓を開けると、外の鳥の声がよく聞こえます。

Both are possible, but the version with the comma is easier to process because the first clause is a bit long.

Japanese commas are often used more flexibly than English commas. They can show:

• a pause
• a change in clause
• improved readability

So the comma here is natural, but not absolutely required.