This document discusses speech signal processing and Persian phonetics. It introduces speech physiology and the source-filter theory of speech production. It describes voiced and voiceless sounds in Persian and their associated acoustic patterns over time, frequency and intensity. It provides examples of fricative consonants [f] and [h] and their output and source signals. In the end, it poses two key questions about relating acoustic patterns to phonetics using pattern recognition approaches and how phonetics can help with speech-to-text conversion of Persian texts.