I feel that Japanese people speak with a voice that is not their own.
I think that people speak English with their natural voice that sounds deep, but with the Japanese people, especially women, they speak with a kind of animation-like voice.
ご質問ありがとうございます。
①
"I feel that Japanese people speak with a voice"=「日本人は~の声で話すと感じる」
"that is not their own."=「自分たちの(声)ではない。」
②
"I think that people speak English with their natural voice that sounds deep"=「人々は英語では、地声で太く話すと思います」
"but with the Japanese people, especially women, they speak with a kind of animation-like voice."=「でも日本人の場合、特に女性は、アニメに似たような声で話します。」
ご参考に!