نسيت السماعة بالبيت، ومشان هيك ما سمعت موسيقى بالطريق.

Because the verb form already includes I.

In Levantine past tense, the ending ـت tells you the subject is I:

• نسيت = I forgot
• سمعت = I heard / listened

So أنا is optional. You could say أنا نسيت السماعة بالبيت for emphasis, but most of the time native speakers leave it out.

Also, this I form is the same whether the speaker is male or female.

Here السماعة means something like the headphones / earphones / headset, depending on context.

A few useful notes:

• سماعة is singular
• سماعات is plural
• In everyday Levantine, people may use either one depending on what device they mean

So in real life, you may also hear نسيت السماعات بالبيت for I forgot the headphones at home.

In Levantine, بـ very often means in / at.

So:

• بالبيت = بـ + البيت
• literally in the house
• naturally at home

This is very common in spoken Levantine.
في البيت is also understandable, but بالبيت sounds more natural in everyday speech.

ومشان هيك means and because of that, so, or that’s why.

Breakdown:

• و = and
• مشان = because of / for / for the sake of
• هيك = like this / this way

But as a whole, مشان هيك is an idiomatic expression meaning:

• so
• that’s why
• for that reason

So the sentence structure is very natural:

• I forgot the headphones at home, so I didn’t listen to music on the way.

Because Arabic often links clauses with و even where English might just use so or nothing at all.

So:

• ومشان هيك = and that’s why / so
• مشان هيك by itself is also possible

The و makes the connection between the two parts feel smooth and natural.

In Levantine, a very common way to negate a past-tense verb is:

• ما + past verb

So:

• سمعت = I heard / I listened
• ما سمعت = I didn’t hear / I didn’t listen

This is one of the most basic and useful negation patterns in Levantine.

It can mean either, depending on context.

In this sentence, it naturally means I listened to music, because the first part mentions forgetting the headphones.

So even though the verb سمع is literally to hear, in everyday Arabic it can also be used in contexts where English would say listen to.

That is why:

• ما سمعت موسيقى بالطريق
  is naturally understood as
• I didn’t listen to music on the way

بالطريق means on the way, on the road, or during the trip/commute, depending on context.

It is:

• بـ + الطريق

In this sentence, the most natural English meaning is:

• on the way
• or during the commute

So ما سمعت موسيقى بالطريق means:

• I didn’t listen to music on the way

It is clearly Levantine / colloquial.

The biggest clue is مشان هيك, which is a spoken expression, not standard formal Arabic.

A more MSA-style version would be something like:

• نسيت السماعة في البيت، لذلك لم أستمع إلى الموسيقى في الطريق.

So the given sentence sounds natural in everyday Levantine conversation, not in formal news-style Arabic.

A rough Levantine-style pronunciation would be:

• nseet is-sammāʿa bil-bēt, w mšān hēk ma smeʿt mūsīʔa biṭ-ṭarīʔ

A few pronunciation notes:

• السماعة is pronounced with s doubled because س is a sun letter
• بالبيت sounds like bil-bēt
• الطريق is often pronounced with a doubled ṭ sound: ṭ-ṭarīʔ
• هيك sounds like hēk

You do not need to pronounce it exactly this way right away, but this is close to natural Levantine speech.

Yes, absolutely.

• نسيت السماعة بالبيت = natural, neutral
• أنا نسيت السماعة بالبيت = also correct, but with extra emphasis on I

Adding أنا can sound like:

• I forgot them
• Me, I forgot the headphones at home

So both are correct, but leaving out أنا is usually more natural unless you want emphasis.