This phonological study investigates the articulatory timing ("phasing") relationships that render acoustic cues optimally recoverable by the listener, and the strong tendency for languages to allow sub-optimal timing patterns only if they allow optimal ones. The primary area of focus is the Otomanguean language group of Oaxaca, Mexico and neighboring states, which possesses "laryngeally complex" vowels, a typologically unusual pattern in which tone and non-modal phonatory settings (breathiness, creakiness)cross-classify. The laryngeally complex vowels of Jalapa Mazatec, Comaltepec, Chinantec, and Copala Trique are studied in depth. Also explored are the phasing relations between obstruents and laryngeals, and sonorants and laryngeals, including phonological analyses from such diverse groups as Mon-Khmer, Tibeto-Burman, and Nilotic, among others. Throughout the investigation, findings from a number of relevant disciplines aerodynamics, acoustics, audition are applied to the sound patterns in an effort not only to describe them in phonetic detail, but also to explain their phonological and typological behavior.