In order to be considered normal, the phonological pattern of a language should include two series of stops, afficates, and fricatives opposed as voiced and voiceless, lenes to fortes, or, in the case of stops and affricates, as non-aspirates to aspirates. Partaking in these two series, we should expect to find from five to ten articulatory types (orders) such as bilabial type, a labiodental type, ans so forth.
- Martinet (1962), a pag.77