Now-a-days, one can observe many applications of Speech Signal Processing. Our voice assistants are just a part of many applications. If you are interested to learn about Speech Signal Processing or want to know about what it is, you are in the right place..! Prepared from the first few chapters of the book called "Digital Processing of Speech Signals", by authors Lawrence R . Rabiner and Ronald W. Schafer (who are MIT graduates!), the PPT can serve as an introduction to the speech signal processing... There are even many other books authored by these signal processing experts. Don't forget to check them too...(click here for the works of Prof. Lawrence)...