At the most basic level of the description of the acoustics of speech, we can say that all speech sounds are made up of just four possible types of acoustic pattern:
1. Periodic sound      (examples:  vowels; nasal consonants)

2. Aperiodic sound    (example:   fricative consonants)

3. A mixture of periodic and aperiodic sound (example: [z])

4. Silence

                                                                  NEXT PAGE