Spectrum characteristic of human voice

The literature review must contain an annotated bibliography..

This section should be an extensive overview of the relevant background literature in your area of research. It should not just summarize the papers you have read, but also organize them in a way that highlights or groups the essential aspects of them.  For example, you might outline how the research area has developed over time, including discussion of major debates.  In short, you should present the reader with a good overview of the important issues or perspectives found in the literature you are reviewing.  What you write must clearly show you have synthesized the material in some way.