The teacher's voice is so quiet that I can't really catch what he/she says.
The teacher speaks so quietly that I can't hear what he/she is saying.
「何を言っているのかあまり聞き取れません」という部分は「I can't really hear/catch what 誰々 is saying」という英語になります。
「先生の声が小さくて」は「The teacher speaks so quietly that...」や「The teacher's voice is so quiet that...」という英語になります。「quiet/quietly」の代わりに「soft/softly」を使う事が出来ますが、「quiet/quietly」の方が英語ネイティブっぽくて自然だと思います＾＾
I should have brought my hearing aid! Can you hear anything he's saying?
Hearing aid = an audio device used to increase the volume of sounds for partially impaired listeners. (partially deaf listeners)
Partially impaired hearing = An impairment that makes hearing difficult for someone.
'My god!'= an exclamation which can express a variety of emotions such as: surprise, shock, happiness, desire, pain etc
'I wish + would' = Used at the beginning of a phrase to indicate that you want or hope that something or someone or some situation will develop in a certain way.
"I wish everyone would stop arguing!"
The teacher speaks very softly, I can hardly hear her.
Something that is soft is very gentle and has no force.
For example, a soft sound or voice is quiet and not harsh.
When you say you can hardly do something, you are emphasizing that it is very difficult for you to do it.
The teacher speaks very softly, I can hardly hear her.
softとは、柔らかく、反発しない、という意味です。
例えば、
a soft sound or voice is quiet and not harsh.
柔らかい音、声とは静かでとがってないものだ。
hardly do something,で、それを行うのが非常に難しいことを表すことができます。
例
The teacher speaks very softly, I can hardly hear her.
すごく柔らかく喋ってくれているが、ききとりはすごく難しい。
The teachers voice is very soft/quiet, she/he could speak up/louder.
The teachers voice can be explained as "soft" or "quiet."
"he/she could speak up/ louder." explains the teacher should speak at a higher volume.
Speak up and louder are both ways of saying higher volume.
I couldn't hear the teacher clearly because she spoke in a soft voice.
I couldn't hear the teacher clearly because she spoke in a quiet voice.
The definition of soft spoken is someone who speaks quietly.
An example of soft spoken is someone who always speaks in a calm and even tone.
To speak in a quiet voice it means to talk in a quiet voice that is difficult to hear.
A) I have no idea what the teacher is saying because she is speaking really soft
B) Can you hear what he/she is saying? i can't hear a thing.
A) I have no idea what the teacher is saying because she is speaking really soft
* idea-a thought or suggestion as to a possible course of action.
Example-"recently, the idea of linking pay to performance has caught on"
*saying-utter words so as to convey information, an opinion, a feeling or intention, or an instruction.
Example-"‘Thank you,’ he said"
*Speaking-used for or engaged in speech.
Example-"you have a clear speaking voice"
*soft-(of a voice or sound) quiet and gentle.
Example-"they spoke in soft whispers"
B) Can you hear what he/she is saying? i can't hear a thing.
*Hear-perceive with the ear the sound made by (someone or something).
Example-"behind her she could hear men's voices"
*Thing-anything (used for emphasis).
noun: a thing
Example-"she couldn't find a thing to wear"
I hope this helps :-)
A) I have no idea what the teacher is saying because she is speaking really soft
* idea-行動選択における考え
例"recently, the idea of linking pay to performance has caught on"
最近は、パフォーマンスの賃金をリンクさせるアイデアが広がっている。
*saying-情報や意見、気持ちや意図、指示を伝えるために単語を発すること。
例"‘Thank you,’ he said"
ありがとうと彼は言った。
*Speaking-スピーチまたはスピーチに関わることに使われる。
例-"you have a clear speaking voice"
君の喋る声ははっきりとしている。
*soft-(声が)静かで優しい.
例"they spoke in soft whispers"
彼らはひそひそと喋っている。
B) Can you hear what he/she is saying? i can't hear a thing.
*Hear-聞き取る.
例"behind her she could hear men's voices"
彼女は自分の後ろで男の声が聞こえた。
*Thing-どんなものでも（強調で使われる）
名詞: a thing
例"she couldn't find a thing to wear"
着るもの何ひとつ見つけられなかった。
お役に立てれば幸いです。
He/she speaks so quietly, I can barely hear him/her!
To explain to someone that the teacher is speaking quietly and therefore you can't hear them, you can say:
"He/she speaks so quietly, I can barely hear him/her!"
「先生の声が小さくて何を言っているか聞き取れない」と先生以外の人に伝えるなら、次のように言えます。
"He/she speaks so quietly, I can barely hear him/her!"
（彼／彼女は声が小さいので、何を言っているのか聞き取れない）
I can't hear what the teacher is saying because he/she speaks in such a quiet voice.
こんにちは。
さまざまな言い方ができると思いますが、下記のような英語表現はいかがでしょうか：
I can't hear what the teacher is saying because he/she speaks in such a quiet voice.
とても小さな声で話すので先生が何を言っているのか聞こえません。
大学の先生（教授）は professor のように言えます。
ぜひ参考にしてください。
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