見える・聞こえる details

が見える

is visible; is audible — something reaches the eyes or ears with nobody trying to perceive it

あ、ここから海うみが見みえる！

a, koko kara umi ga mieru!

Oh, you can see the sea from here! casual

部屋へやの窓まどから、景色けしきが見みえます。

heya no mado kara, keshikigamiemasu.

From the window of the room, the scenery is visible. neutral

Examples

comes into view or within earshot — the thing perceived is the subject, and nobody is credited with perceiving it

あ、ここから海うみが見みえる！

a, koko kara umi ga mieru!

Oh, you can see the sea from here! casual

部屋へやの窓まどから、景色けしきが見みえます。

heya no mado kara, keshikigamiemasu.

From the window of the room, the scenery is visible. neutral

隣となりの部屋へやから、小ちいさい声こえが聞きこえた。

tonari no heya kara, chiisai koe ga kikoeta.

A quiet voice came through from the next room. neutral

恐おそれ入いりますが、お声こえが少すこし聞きこえにくいようです。

osoreirimasu ga, o koe ga sukoshi kikoenikui you desu.

I'm sorry, but your voice seems a little hard to hear. formal

お見えになる — a second, unrelated job for the same verb — the polite way to say that a visitor has arrived, 三時さんじにお客様きゃくさまがお見みえになりました.

The thing perceived takes が, never を (×海うみを見みえる); the person it
reaches takes に, in practice almost always には — 私わたしにはよく見みえない.

がする
音おとがする reports an impression with its source unplaced; 音おとが聞きこえる reports it reaching a particular ear, which is why 聞きこえる takes an experiencer (私わたしには聞きこえない) and がする cannot — ×私わたしには音おとがしない.

られる（可能）
見みえる is not the potential of 見みる — it says the thing arrives at the eye unbidden (窓まどから海うみが見みえる), while 見みられる says an opportunity exists (その映画えいがはネットで見みられる); 聞きこえる and 聞きける split the same way.
〜く見える・〜に見える・〜く聞こえる・〜に聞こえる
The same verb, and on a noun host one particle decides everything — 子こどもが見みえる reports a child in view, 子こどもに見みえる reports that whoever you are looking at passes for one, so が answers "is it there?" while に and く answer "what does it come across as?".