Editing Articulatory phonetics (section)

==Sound sources==

Sound sources refer to the conversion of aerodynamic energy into acoustic energy. There are two main types of sound sources in the articulatory system: periodic (or more precisely semi-periodic) and aperiodic. A periodic sound source is vocal fold vibration produced at the glottis found in vowels and voiced consonants. A less common periodic sound source is the vibration of an oral articulator like the tongue found in alveolar trills. Aperiodic sound sources are the turbulent noise of fricative consonants and the short-noise burst of plosive releases produced in the oral cavity.

[[Voice (phonetics)|Voicing]] is a common period sound source in spoken language and is related to how closely the [[vocal cord]]s are placed together. In English there are only two possibilities, ''voiced'' and ''unvoiced''. Voicing is caused by the vocal cords held close by each other, so that air passing through them makes them vibrate. All normally spoken vowels are voiced, as are all other sonorants except ''h'', as well as some of the remaining sounds (''b'', ''d'', ''g'', ''v'', ''z'', ''zh'', ''j'', and the ''th'' sound in ''this''). All the rest are voiceless sounds, with the vocal cords held far enough apart that there is no vibration; however, there is still a certain amount of audible friction, as in the sound ''h''. Voiceless sounds are not very prominent unless there is some turbulence, as in the stops, fricatives, and affricates; this is why sonorants in general only occur voiced. The exception is during [[whispering]], when all sounds pronounced are voiceless.

===Periodic sources===

* Non-vocal fold vibration: 20–40 [[hertz]] (cycles per second)
* Vocal fold vibration
** Lower limit: 70–80&nbsp;Hz modal (bass), 30–40&nbsp;Hz creaky
** Upper limit: 1170&nbsp;Hz (soprano)

====Vocal fold vibration====

* [[larynx]]:
** [[cricoid cartilage]]
** [[thyroid cartilage]]
** [[arytenoid cartilage]]
** [[Arytenoid muscle|interarytenoid muscles]] (fold adduction)
** [[posterior cricoarytenoid muscle]] (fold abduction)
** [[lateral cricoarytenoid muscle]] (fold shortening/stiffening)
** [[thyroarytenoid muscle]] (medial compression/fold stiffening, internal to folds)
** [[cricothyroid muscle]] (fold lengthening)
** [[hyoid bone]]
** [[sternothyroid muscle]] (lowers thyroid)
** [[sternohyoid muscle]] (lowers hyoid)
** [[stylohyoid muscle]] (raises hyoid)
** [[digastric muscle]] (raises hyoid)