When a person speaks, voice problems usually include pain or discomfort and/or difficulties in terms of the pitch, the loudness and the quality of the voice. When patients with voice problems induced by stroke, Parkinson’s disease, and systemic diseases involving the voice are examined, generally, of the Four Diagnoses (四診), a Diagnosis of Hearing can be used in current Korean medicine. The effects of acupuncture and herb medicine on voice problems have been reported for over 20 years. However, when it comes to improvements, objective and subjective evaluation methods need to be explained.
Subjective methods for evaluating voice were studied through a literature search of old medicinal books containing Korean medicine diagnostics, and an objective evaluation method using Praat software is presented.
Korean medicine doctors analyze the patient’s voice in clinical settings unconsciously on a daily basis. However, most voice diagnoses depend on the doctor’s subjective evaluation. Voice qualities can be evaluated by using the Eight Principles (八綱), including Yin-Yang; the Five Elements (Phases); the Grade, Roughness, Breathy, Asthenic, Strained (GRBAS) score, and the Visual Analogue Scale (VAS) as subjective methods, and an acoustic analysis using the Praat program can be used as an objective method.
A more complete voice examination can be achieved by using subjective and objective methods at the same time. For an objective explanation and management of patient’s voice problems or systemic disorders, an objective method should be used in Korean medicine, which already has many subjective diagnostic methods. More research needs to be conducted, and more clinical evidence needs to be collected in the future.
Sound is caused turbulent changes in a gas, such as air, a fluid or a solid, and the sounds of the human voice are created by vibrations of the vocal cords [
The book Dongeuibogam explains many kinds of acute and chronic dysphonia or aphonia (voiceless disease): for example, those after drinking alcohol and being invaded by Wind, those after being invaded by Wind and Cold, dysphonia induced by cerebrovascular accident, dysphonia induced by shortage of Blood and Qi, etc. The book also describes the treatment method for dysphonia [
Many doctors are interested in treating hoarseness and dysphonia or dysphasia (dysarthria) induced by strokes or Parkinson’s disease and in evaluating the character of the voice and the degree of dysphasia [
The human voice comes from below the vocal cords and changes due to the vocal tract, oral cavity, nasal cavity, etc. [
There are many voice-analyzing variables, but considering medical aspects, a few basic variables can be summarized: for instance, the fundamental frequency (F0), the standard deviation of the fundamental frequency (F0 SD), the formant, the jitter, the shimmer and the harmonics-to-noise ratio (HNR). The degree of high and low as to what a human can hear and understand is called pitch. Pitch can be assumed to be the fundamental frequency in terms of the voice-analyzing variables [
The formant frequency, or the resonance frequency, is made in the vocal cord and is the one harmonic frequency among several multiple harmonics that coincides with the speaker’s characteristics. According to a person’s own articulator, a person generally has 3 or 4 harmonics. From lowest to the highest frequency, those harmonics are named as F1, F2, F3 and F4. Especially, F1 and F2 have importance because they are affected by the position of the tongue and the size of the oral cavity [
Jitter and Shimmer may also be good surrogate markers or indicators for comparing a normal voice to an abnormal one. Jitter evaluations are used to study stuttering and vocal pathology, especially vocal-cord regulating problems [
The human voice can be evaluated in two ways, one of which is hearing by the ears and the other is using hardware or a software program. Generally speaking, using both ways to evaluate a patient is best. Sound analyzers have been developed since the late 1940’s and have changed from analogue to digital. One of the most frequently used voice analyzers is Computerized Speech Lab (CSL) made by Kay Elemetrics (USA) [
2.3.1. Classification by Yin-Yang
Yin-Yang is the fundamental icon that represents east Asia or China. Yin-Yang is regarded as a general word in daily life nowadays and has opposing and complementary views at the same time. If classification is to be accomplished, then an opposing view is needed. If a patient’s voice can be categorized as clear, high-pitched, strong, and fast, then that person’s voice can be said to have the property of Yang. On the contrary, if the voice is categorized as thick, low, weak and slow, then the voice can be said to have the property of Yin. If voice is more precisely divided according to the Eight Principles (八綱), there is the Yang property, the Excessive property, and the Heat property for a patient who has a high-pitched, strong, powerful voice. On the other hand, there is the Yin property, the Empty property, and the Cold property for a patient who has a low, powerless, thin voice, who does not like to talk, or who has difficulty in talking and sometimes speaks with voice breaks [
2.3.2. Five voices
Five Voices sometimes are regarded as the same notion of five sounds, but in an exact meaning, five voices are more formal than five sounds [
In recent Chinese five voices treatment music, Gung music is in C major scale and has bright and calm feelings. On the contrary, Sang music is in D major and uses many kinds of metal musical instruments, has heavy and slowly ascending feelings. Gak music is in E major and uses many kinds of wooden musical instruments, so it gives the most cheerful, lightest and vivid feelings Chi music is in G major and it gives a magnificent and soft feeling in a serial order. Wu music is in A minor, so it gives a dark, slow, tragic and restrained feeling [
2.3.3. Five sounds
Five sounds are regarded as more natural, original sounds than five voices [
2.3.4. Grade, roughness, breathy, asthenic, strained (GR BAS) evaluation
GRBAS is an acronym for Grade, Rough, Breathy, Asthenic and Strained. The GRBAS method has been used in Japan for a long time tor evaluate patients with vocal pathologies. By listening to the voices from the patients, trained professionals evaluate the overall grade and degree of roughness, breathiness, asthenia, and strain. It is a 4-point system in which item ranges from 0 (normal) to 3 (very severe) [
2.3.5. Visual analogue scale evaluation
The VAS is used to evaluate pain and general health condition. Generally, it ranges from 0 to 10 or from 0 to 100, where 10 or 100 means a patient has the most severe pain. A patient with a vocal pathology, such as dysarthria, dysphonia, aphonia, hoarseness, Parkinson’s disease, etc., can also be evaluated using the VAS.
Articulation of the voice might have been a curious thing for ancestors who treated patients, and descriptions of the articulators of the voice, such as the vocal cord, the vocal tract, the lips, the mouth, etc., have been found in old traditional medicine books. Five voices and five sounds were connected with five elements in physiological aspects; moreover feelings of voices were allocated to each of the five elements in pathological and diagnostic areas. Thus, each voice can give information about diseases of the five organs through the feelings of voices and about diseases of the six bowels through the properties of voices: clear/thick, high-pitched/low-pitched, powerful/powerless, and fast/slow. The five voices and five sounds used to be useful for diagnosing a patient’s disease and health condition based on the Eight Principles such as the Yin-Yang property, Empty/Excessive, Exterior/Interior, and Heat/Cold.
For example, 『Classic of Difficult Issues (難經)』 says that the five organs govern the five voices [
Although doctors in clinical settings are not aware of using voice examinations, they are always hearing and listening to what their patients say, so they are considering pattern identification during the discussions with the patient. They can sense the voice volume, the feeling of the voice, and the habits of speaking subconsciously. We can consider one more thing here: not only is a subjective voice examination important, but so is objective voice examination. Thus, what should be done to carry out an objective voice examination?
Doctors can identify patterns like the Yin pattern, the Deficiency pattern, and the Cold pattern through the patient’s voice being generally weak voice generally and patterns like the Yang pattern, the Excessive pattern and the Heat pattern through the patient’s voice being strong or powerful. Thus, the Eight Principles can be used in subjective voice examination with ease. However, when it comes to Goong, Sang, Gak, Chi, and Wu voices and the five sounds, standardization and consensus among health professionals are thought to be needed for clinical applications. Reliability, objectivity and standardization are important areas of diagnosis in Korean medicine. GRBAS and VAS use both subjective and objective criteria. Therefore, a scientific analysis, such as one using voice-analysis software, could be one option to measure the treatment outcome after Korean medicine treatment for voice-related diseases or systemic diseases (Fig 1).
Nowadays, voice is regarded as a necessary factor for communicating well, and voice-related problems, such as hoarseness, dysarthria and dysphonia, could possibly be used to compare the effects of Korean medicine treatments. When it comes to hoarseness for example, the points of view are different between Western medicine and Korean medicine. In Korean medicine, voice is affected not only by the vocal cords and the muscles surrounding the vocal cords, but also by many other factors, such as accommodations of the Lungs, Kidneys, and Liver for a high-pitched voice and of the Spleen for a soft voice, resonance through the Liver and the Spleen, and the emotional effect through the Heart and the Pericardium [
If effective treatment and management for patients with voice-related problems are to be achieved, in addition to the current subjective evaluation methods using Yin-Yang and Five Elements, including five voices and five sounds, an objective evaluation method using voice analytic software and a grading method for severity are needed. If eight principles and five voices and five sounds are combined with GRBAS and the VAS scoring system, a subjective voice examination can be done. Moreover, performing an objective voice examination using software in treating patients with voice problems and patients with systemic diseases with voice problems should be helpful in monitoring and managing those patients.