Phonetics is the scientific study of speech sounds, including how they are produced (articulatory phonetics), transmitted (acoustic phonetics), and perceived (perceptual phonetics). The document discusses the different types of speech sounds like vowels, consonants, diphthongs, and affricatives. It describes how each type of sound is articulated using specific organs like the lips, tongue, teeth, and soft palate. Key speech sounds in English like /b/, /p/, vowels, and fricatives are explained in terms of their place and manner of articulation.