Editing Voice analysis (section)

==Analysis methods==
Voice problems that require voice analysis most commonly originate from the vocal folds or the laryngeal musculature that controls them, since the folds are subject to collision forces with each vibratory cycle and to drying from the air being forced through the small gap between them, and the laryngeal musculature is intensely active during speech or singing and is subject to tiring. However, dynamic analysis of the vocal folds and their movement is physically difficult. The location of the vocal folds effectively prohibits direct, invasive measurement of movement. Less invasive imaging methods such as [[x-ray]]s or [[ultrasound]]s do not work because the vocal cords are surrounded by cartilage, which distorts image quality. Movements in the vocal cords are rapid, [[Fundamental frequency|fundamental frequencies]] are usually between 80 and 300 [[Hertz|Hz]], thus preventing usage of ordinary video. [[Stroboscope|Stroboscopic]], and high-speed videos provide an option, but to see the vocal folds a fiberoptic probe leading to the camera must be positioned in the throat, which makes speaking difficult. In addition, placing objects in the pharynx usually triggers a gag reflex that stops voicing and closes the larynx. In addition, stroboscopic imaging is only useful when the vocal fold vibratory pattern is closely periodic.

The most important{{According to whom|date=February 2022}} indirect methods are currently [[inverse filter]]ing of either microphone or oral airflow recordings and [[electroglottograph]]y (EGG).{{Citation needed|date=November 2021}} In inverse filtering, the speech sound (the radiated acoustic pressure waveform, as obtained from a microphone) or the oral airflow waveform from a circumferentially vented (CV) mask is recorded outside the mouth and then filtered by a mathematical method to remove the effects of the vocal tract. This method estimates the glottal input of voice production by recording output and using a computational model to invert the effects of the vocal tract. The other kind of noninvasive indirect indication of vocal fold motion is the electroglottography, in which electrodes placed on either side of the subject's throat at the level of the vocal folds record the changes in the conductivity of the throat according to how large a portion of the vocal folds are touching each other. It thus yields one-dimensional information of the contact area. Neither inverse filtering nor EGG are sufficient to completely describe the complex 3-dimensional pattern of vocal fold movement, but can provide useful indirect evidence of that movement.

Another way to conduct voice analysis is to look at voice characteristics. Some characteristics of voice are [[phonation]], [[Pitch (music)|pitch]], [[loudness]], and rate. These characteristics can be used to evaluate a person's voice and can aid in the voice analysis process. Phonation is typically tested by looking at different types of data collected from a person such as words with long vowels, words with many phonemes, or just typical speech. A person's pitch can be evaluated by making the person produce the highest and lowest sounds they can, as well as sounds in between. A keyboard can be used to aid in this process. Loudness is valuable to look at because for certain people, loudness affects the way they produce certain sounds. Some people need to speak louder for certain phonemes in comparison to others just so they can produce them.{{Citation needed|date=November 2021}} This can be tested by asking the person to use the same amount of loudness while singing a scale. Rate is also important because it looks at how fast or slow a person speaks.

<ref>{{cite book|last1=Hapner|first1=Edie|last2=Stemple|first2=Joseph|title=Voice Therapy: Clinical Case Studies|date=2014|publisher=Plural Publishing}}</ref>