Harsh: This describes a voice that is rough and unpleasant to listen to.
Raspy: This is similar to harsh, but it also implies a certain kind of dryness or hoarseness.
Strident: This describes a voice that is sharp and piercing, almost like a screech.
Gruff: This describes a voice that is deep and rough, often associated with a masculine or authoritative presence.
Unpleasant: This is a general term that encompasses any voice that is not enjoyable to listen to.
Screeching: This specifically describes a high-pitched, piercing voice that is unpleasant to hear.
Hoarse: This describes a voice that is rough and strained, often caused by illness or overuse.
Monotone: This describes a voice that lacks variation in pitch and inflection, making it sound boring or unengaging.
Other: There are many other ways to describe the opposite of a sweet voice, depending on the specific context. For example, a voice might be described as harsh, cold, unsympathetic, or dissonant.
Ultimately, the best way to describe the opposite of a sweet voice depends on the specific qualities you want to emphasize.