The use of term ‘voice’ is variable with the context. Voice can be described as the right to opinion or a right to speak. The other case is that of the human voice. It is a major part of human communication. The human sound system produces voice for talking, singing, screaming, laughing and crying. It is a process that occurs within the sound box in humans and with the support of other subsystems.
Voice is the product of three subsystems. They include the respiratory system, laryngeal system and articulatory system.
Air Pressure System
The functioning of the diaphragm, abdominal muscles, chest muscles, lungs and ribs are vital for producing voice. It regulates the air pressure necessary to vibrate the vocal folds (structures present in the voice box).
The laryngeal system is the vibratory source. It houses the vocal folds, viz., two muscle bands covered in layers of tissues. The air pressure from the lungs is modified into sound waves by the vibration of the vocal folds. It also helps in varying the pitch and loudness of the produced sound.
The vocal tract includes structures like pharynx, oral and nasal cavities. These structures produce recognizable speech sounds by modifying the sound from the larynx.
The three subsystems work together to produce the end product that we hear when we speak.
Apart from voice production, the vocal mechanism plays an important role in:
- Breathing: Keeping the airway open without obstructions for air to flow in and out of the lungs.
- Swallowing: Prevents food from entering the airway by keeping the glottis closed.
- Cough Reflex: Builds up appropriate pressure for the forceful expulsion of food/ foreign objects that has entered the airway by mistake.
A disordered voice is a change in quality, pitch, and loudness that is inappropriate to age, gender, and context. These conditions can interfere with the daily routine of a person. The individual can seek treatment even when others do not perceive deviance and the individual expresses concerns.
Voice disorders are distinguished into types to help the professional identify underlying pathology and treat appropriately.
Organic Voice Disorders
The physiological changes that occur due to alterations of the structures in subsystems causes the organic voice disorders. They can further be divided into structural and neurogenic organic voice disorders.
Structural Disorders: It is caused by the physical changes that occur in the vocal tract due to ageing or alterations in vocal fold tissues.
Neurogenic Disorders: The result of damage to the central or peripheral nervous innervation to the vocal structures. Shows up in the form of vocal tremor, spasmodic dysphonia or vocal fold paralysis.
Functional Voice Disorders
Inefficient or inappropriate use of the vocal mechanism can lead to vocal fatigue, muscle tension aphonia/dysphonia, diplophonia or ventricular phonation. These are signs or symptoms of functional voice disorders.
Psychogenic or Psychogenic Conversion Aphonia/ Dysphonia
Psychological stressors will lead to maladaptive aphonia or dysphonia that are habitual in nature. They are collectively called ‘Psychogenic Conversion Aphonia/ Dysphonia. It causes a significant change in the quality of voice of an individual, hindering his/ her everyday life.
Other Aerodigestive Disorders (not classified as voice disorders) like Paradoxical Vocal Fold Movement and Exercise-induced Laryngeal Obstruction also require treatment by a team of ENT and Speech-Language Pathologist (SLP).
Signs & Symptoms
- An increase in vocal effort while speaking accompanied by vocal fatigue, pain, tension or tenderness
- Reduced vocal endurance with prolonged voice usage
- Variable vocal quality (rough voice – raspy or aperiodic; breathy – audible air escape while speaking; strained/ strangled voice – increased effort with harshness)
- Frequent coughing or throat clearing (may worsen with increased voice use)
- Abnormality in pitch (too low, too high, inappropriate to age or gender) or inability to vary pitch
- abnormal loudness/volume
- abnormal resonance (hypernasal, hyponasal, cul-de-sac resonance);
- Complete loss of voice or breaks in between while speaking continuously
- Asthenia – weak voice; Tremors in voice while speaking
Role of a SLP
SLPs play a central role in the diagnosis and treatment of voice disorders. The various activities include clinical services, prevention, advocacy, education, and research. Whenever a need arises, SLPs may collaborate with otolaryngologists, Neurologists, Mental Health Professionals, Pulmonologists, Gastroenterologists, and vocal coaches to decide on the best treatment approach.