The voice is a sound produced by the larynx from pulmonary exhaled air, which is then amplified and reinforced by resonant cavities (pharynx, nasal cavity, oral cavity and the lips). But, in addition, the voice not only reflects but is influenced by the different moods of the person, their personality, health, etc.
The brain governs the implementation of the vocal instrument and directs the execution of the muscle activity involved (rib cage, lungs, vocal cords and resonators).
Dysphonia is the alteration of some of the acoustic qualities of the voice (intensity, pitch, timbre and duration) as a consequence of an organic disorder or improper use of the voice (functional) and can be permanent or temporary. Therefore, aphonia would be the total loss of the voice.
The etiology of speech disorders may be organic, physiological, psychological or environmental, and there are some factors that determine the appearance or duration of such alterations, and even the worsening thereof, such as respiratory diseases (laryngitis, chronic bronchitis, asthma, vegetations, etc.), laryngeal malformations, surgery, laryngeal trauma, respiratory use and improper speech, behavioural characteristics, the family and social environment, and hearing impairment, among other things.
Determining how and to what degree a voice is pathological is not always easy, because there are multiple factors that directly influence the estimation (affective and emotional circumstances, cultural, age, gender, professional standards, self assessment of one’s own voice, etc.) . Therefore, in order to accurately diagnose vocal pathology it is necessary to conduct a comprehensive and thorough study, which includes, in addition to the data on family and personal history, and the history of the disease, an organic exploration of the pharynx, larynx and resonant cavities, a functional examination of the posture, respiratory phonological coordination, vocal sound and maximum phonation and exhalation time, laryngeal function testing by way of laryngostroboscopy or fibroscopy, and an acoustic voice analysis of fundamental frequency, tonal extent, intensity and phonetogram.
Dysphonia can be classified according to three criteria:
- Aphonia: Total loss of voice.
- Dysphonia voice alteration in any of its qualities.
- Laryngophony: Dysphonia located in the larynx, causing bad voice projection (inappropriate tone), vowel hoarseness (strong voice, no timbre and too deep), functional laryngitis (inflammatory processes due to prolonged shouting) and phonasthenia or vocal fatigue (weak shallow voice with no timbre).
- Rhinophonia: changes in the resonance or nasalization of phonation. This can be:
. Open rhinophonia: the air escapes through the nose during phonation.
. Closed rhinophonia: nasal obstruction that prevents the passage of air through the nostrils.
- Organic dysphonia: caused by lesions in the phonation organs due to causes that are congenital (brain lesions, malformations, paralysis, endocrine factors, etc.), inflammatory (acute and chronic laryngitis) and traumatic (injury wounds, burns, radiation therapy, surgery, etc.).
- Functional dysphonia: produced by altered vocal attitude that can be complicated by organic lesions of the larynx caused by vocal strain (nodules) or transient organic disorders (laryngitis). These are triggered by acute laryngitis, injuries and allergies, psychological factors, systemic diseases, etc. Predisposing factors to speaking or singing, personal psychological characteristics, consumption of tobacco and alcohol, chronic ENT conditions, poor audio-phonatory control, poor vocal technique, exposure to excessive noise, dust, irritating vapours, etc.
According to the alteration of the vocal attitude and how the patient compensates, one can distinguish between two types of functional dysphonia:
. Hypertonic or hyperkinetic: Excessive tension of the vocal cords during phonation with stress behaviour.
. Hypokinetic or hypotonic: the vocal cords are not completely closed due to lack of muscle tension, with compensation from the adjacent structures.
In the case of functional dysphonia, vocal effort behaviour can lead to an objective laryngeal alteration, known as functional laringopathies, alterations of the mucosa of the vocal fold caused by a vocal behaviour impairment, causing the formation of nodules and polyps.
In general, organic dysphonia requires surgery and then rehabilitation, whereas functional dysphonia requires speech therapy, although, depending on the case, they may require surgery or medication.
The speech therapy intervention for speech disorders is aimed at restoring proper posture and proper breathing mechanics, reduce muscle tension and eliminate laryngeal effort, as well as adapt the cavity resonance to the sound emitted from the larynx.
At the beginning of the vocal therapy detailed information must be provided to patients, as appropriate, on proper vocal hygiene aimed at reducing vocal aggression and carrying out active prevention, providing advice on reducing toxic habits and predisposing factors (dry, cold or very hot environments, sudden temperature changes, etc.), not using the voice over long periods, properly treating impairments and infections of the upper airways, maintaining a lifestyle that is as healthy as possible, using the voice at a moderate level, etc.
The vocal therapy consists of restoring a proper postural attitude to get the best voice with the least possible effort, relaxation exercises to reduce muscle tension, breathing exercises designed to lengthen phonation, regulation of breathing, an increase or decrease in the volume of the voice and correct breathing and restoration of the impaired sound qualities (intensity, duration, pitch and timbre).