YOU SAID:

I can't hit high notes.

INTO JAPANESE

高い音が出ない。

BACK INTO ENGLISH

There is no high sound.

INTO JAPANESE

高い音は出ません。

BACK INTO ENGLISH

There is no high-pitched sound.

INTO JAPANESE

高音は出ません。

BACK INTO ENGLISH

There is no treble.

INTO JAPANESE

高音はありません。

BACK INTO ENGLISH

There is no treble.