If you are considering vinyl doors, they can offer a sense of privacy, but they also offer some degree of noise dampening. The level of noise it produces depends on the material it is made from. Vinyl is said to be the quietest door available. However, vinyl doors can become warped if not properly installed. Vinyl doors are also more prone to mold and mildew than wood.
If you are interested in making your home quieter and more peaceful, consider upgrading your interior doors. They are an easy and inexpensive way to improve the feel of your home and to reduce noise. In addition, the effort is likely to pay off in increased resale value.