Is it permissible for a woman to create a YouTube channel to present scientific and beneficial content using only her voice, while adhering to the guidelines of not showing any part of her body and avoiding softening or sweetening her voice?

A woman's voice is not considered 'awrah' (private and unlawful to expose) unless it involves softness, a captivating tone, or laughter and submissiveness in speech. If the listener derives pleasure from it, or fears temptation for himself, then it is impermissible for him to listen to it; otherwise, it is not forbidden. It is not permissible for a woman to soften or make her voice alluring, as this could incite temptation, in accordance with the Almighty's saying: "So do not be soft in speech [to men], lest he in whose heart is disease should covet." (Quran 33:32). If the audio clips contain beneficial content and are free from softness or alluring tones, then there is no harm in them. However, if they are restricted to women, that would be preferable.