Table 2.

Speech analyses used in DFD studies^*.

Analysis Type	Analysis	Description
Perceptual	Live perceptual evaluation	Real time visual/perceptual evaluation by a speech pathologist at scheduled time intervals.
Perceptual	Perceptual evaluation of recordings	Visual/perceptual evaluation from a video/audio recording by a speech pathologist at scheduled time intervals.
Acoustic	Cephalometric analysis	Utilizing lateral cephalometric radiographs to analyze bony and soft tissue landmarks to relate the cranial base, maxilla, and mandible to the teeth.
Acoustic	Electropalatography	Utilization of a palatal stent with electrodes to record tongue and palate contacts during speech.
Acoustic	Formant analysis of vowels	A method used to analyze vowel pronunciation. The first formant (F1) and the second formant (F2) are typically extracted from a speech recording. An F1xF2 vowel plot is then used to display vowel sound distribution.
Acoustic	Spectral moment analysis	A type of spectral analysis typically used to describe consonants. The power spectrum is treated as if it is a probability distribution.
Acoustic	Spectral peak analysis	A type of spectral analysis typically used to describe consonants. Spectral peaks are measured.
Acoustic	Tongue thrust evaluation	Visual analysis of tongue position during different actions. Tongue position is ranked on a subjective, predetermined scale.
Acoustic	Velopharyngeal evaluation	Estimation of the size of velopharyngeal port area using pressure–flow measurements while participants are asked to repeat pressure sounds, such as [p].

^*Includes speech analysis methods used in DFD studies. This is not an exhaustive list of all available speech analyses.