A voice that is high pitched (perhaps squeaky or sharp in tone) can be referred to as a high voice.
The opposite can be a 'quiet voice' which means that it is quiet in sound, difficult to hear or like a whisper.
In terms of singing, a low voice is someone with a deep or baritone voice. It means they are not able to reach high pitched notes but specialize in the lower end of the musical scale.
I hope that helps!
高い声（キーキーしていたり鋭いトーンの声など）は、a high voice と表すことができます。
その反対は a quiet voice です。これは静かな音で、ささやいているような聞き取りにくい声のことです。
歌に関しましては、低いバリトンの音程の場合は a low voice といいます。これは高いピッチを出すことができず、低いキーを専門に歌う方のことを言います。
参考になればうれしいです！
A bass voice: the lowest adult male singing voice.
"John's a singer with a bass voice."
When describing such a person you could say,
"Paul has a deep, resonating voice. I love it because it seems so manly!"
A bass voice: 男性の一番低音の歌声
"John's a singer with a bass voice." ジョンは低音の歌手だ。
そういう人のことを表現する場合は以下のように言えます。
"Paul has a deep, resonating voice. I love it because it seems so manly!" ポールは低くて響く声をもってる。男らしくていい声だ。
You can say someone is soft spoken. This an adjective that means someone who speaks quietly.
An example of soft spoken is someone who always speaks in a calm and even tone.
A low voice is the opposite of a high voice. We can also express this as a deep voice. All low sounds can be described as deep sounds. We also use the phrase bass voice sometimes, i think this comes from music terminology.
To express the opposite to high voice, feel free to use any of these two expressions. Both of them mean absolutely the same and do not hesitate to use them.
A low voice example sentence: The boy in my class always speaks in a low voice because he likes to talk to his friends during class time.
A soft tone example sentence: Please speak in a soft tone because the patients are trying to sleep in the next room.
A quiet voice example sentence: The old woman spoke in a quiet voice over the phone because she was not feeling well.
We can use these three different adjectives: low, quiet or deep to express a voice that is the opposite of a high voice.
Example sentences :
He spoke to me in a low voice.
She had a very quiet voice.
He responded to me in a very deep voice.
インド 
イギリス 
日本 
南アフリカ 
アメリカ合衆国 
