This is also known as pitch perturbation and refers to the minute involuntary variations in the frequency of adjacent vibratory cycles of the vocal folds. Pathological voices often exhibit a higher percentage of jitter. Whereas jitter is a measure of the percentage irregularity in the pitch of the vocal note pitch perturbation , shimmer is a measure of the percentage irregularity in the amplitude of the vocal note. It is often referred to as amplitude perturbation. Shimmer, therefore, measures the variability in the intensity of adjacent vibratory cycles of the vocal folds.
As with jitter, pathological voices will typically exhibit a higher percentage of jitter. The vocal note produced by the vibrations of the vocal folds is complex and made up of periodic regular and repetitive and aperiodic irregular and non-repetitive sound waves.
The aperiodic waves are random noise introduced into the vocal signal owing to irregular or asymmetric adduction closing of the vocal folds. Noise impairs the clarity of the vocal note and too much noise is perceived as hoarseness. Praat is capable of measuring the proportions of periodic and aperiodic waves noise in the vocal note and displaying this as a Harmonics-to-Noise HNR ratio. Laryngeal pathology may lead to poor adduction of the vocal folds and, therefore, increase the amount of random noise in the vocal note.
The greater the proportion of noise, the greater the perceived hoarseness, and the lower the HNR figure will be, i. Figure 1 represents jitter, shimmer and HNR diagrammatically. For adult males this is around Hz cycles per second , for adult females it is about Hz, and for children under the age of 10 years it can average Hz.
Subtracting the minimum pitch from the maximum pitch gives the pitch range. This is an indicator of flexibility, representing a measure of how much the client varies their pitch during speech.
Typical pitch ranges are Hz for adult males and Hz for adult females. Instrumental Measurement of Voice 1 February Graham Williamson. More commonly, this is due to a psychogenic muscle tension dysphonia. In rare cases, there may be a dominant cerebral hemisphere lesion affecting Broca area causing an apraxia of phonation, while other widespread cortical lesions cause mutism. This can be in the form of pitch breaks where the voice cracks, squeaks, or becomes usually high pitched.
Pitch breaks can be used with effect in singing when these are known as register transitions 34 or mode changes. Alternatively, the voice may cut out all together. Voice breaks result when some parameter of the vibrating system is changed e. Voice breaks may also be present when the vocal folds are inflamed, there is a primary muscle tension imbalance such as puberphonia or secondary tensioning asymmetries such as a superior laryngeal nerve palsy.
This is when two distinct pitches can be perceived simultaneously during phonation. It can result from tensioning imbalance in primary muscle tension dysphonia, secondary to a subtle neurological weakness such as a paresis, 36 or when there is a difference in mass between the two vocal folds due to a structural abnormality such as an intracordal cyst.
There may also be associated voice breaks. Tremor is a regular wobble or shakiness of the voice 5 to 12 Hz. It is more common in the elderly in isolation or as one of several tremors affecting different parts of the body essential tremor. It can be present together with other neurological conditions such as cerebellar ataxia 2 or 3 Hz , spasmodic dysphonia irregular frequency , 38 and late-stage Parkinson disease 4 to 7 Hz. The fundamental frequency of the voice is the measurable vibratory frequency of the sound source, which is in most cases the vocal folds.
These include anatomical, physiological, social, and cultural influences. As a rough guide, the mean fundamental frequency of adult men during speech ranges between and Hz, between and Hz for adult women, and between and Hz for children.
Pragmatically, the inappropriateness of the pitch is defined as that judged by the patient and assessor to be outside the normal range based on the age and sex of the individual.
This is quite a common perceptual finding but is rarely a complaint in women except when the voice has changed or is associated with other vocal complaints. In women, the commonest cause is muscle tension imbalance lateral compression or Morrison Type 2 resulting from habitual talking at the top of the range of the voice, a common tendency in primary school teachers.
In men, a high-pitched voice can cause negative comments about gender and lead to ridicule and psychological problems. Structural abnormalities and neurological problems need to be excluded. Structural problems include sulcus vergeture and an anterior glottis web. In sulcus vergeture, there is a longitudinal groove in the membranous portion of the vocal fold and is frequently bilateral. There is tethering of the epithelium to the underlying ligament or vocalis muscle.
The consequence is a high-pitched voice with reduced pitch range. The voice can also be breathy, lack power, and projection.
Both can cause significant high-pitched voices and dysphonia. In recurrent laryngeal nerves palsies, the compensatory unbalanced pull of the laryngeal muscles leads to asymmetry of the glottis and stretching of the vocal folds. This leads to a high-pitched voice with the breathiness from glottal gap. In advanced Parkinson disease, the mean speaking fundamental is raised compared with age-matched men but not in women and not for early-stage disease.
A low pitch to the voice is a much more common complaint in women who often get comments about sounding like a man, particularly on the phone. The most common cause is Reinke edema in which there is an increased amount of extracellular matrix produced in the superficial lamina propria. The whole pitch range may have shifted, often becoming lowered. This can result from natural changes with age or from the structural effects of increasing the mass of the vocal folds, for example, from smoking.
The pitch range may have become narrowed or monopitch, that is, lacks variation in speech. This can be due to personality issues, anxiety, and depression. It can also be a feature of neurological conditions such as Parkinson disease 39 , 48 and in recurrent laryngeal nerve palsy. Singers who are struggling with their pitch range may, for example, need to change key to sing a range of notes in a specific song.
Loss of the top end of the range of the voice or difficulty with certain parts of their range may be because of inadequate technique in making transitions between registers or modes of the voice. Reduced loudness of the voice may result from neuromuscular problems such as vocal fold palsies or paresis, Parkinson disease, or myasthenia gravis where there is a physical inability to oppose the vocal folds.
Sometimes the loudness reduces with voice use. Alternatively, it may only be an issue in noisy environments or when there is a need to project the voice.
Most patients will not complain about this but it may be apparent to the listener. It is common in muscle tension dysphonia when it may be a manifestation of an extrovert personality, a need to be heard when there are other dominant siblings or when the voice cannot be regulated when there is an untreated hearing loss. Occasionally, it may be necessary to increase the subglottic pressure to overcome the inertia of the vocal folds from structural or inflammatory causes.
The result can be uncontrolled regulation of loudness and may be associated with voice breaks. Throat symptoms may be present with any of the four etiologic conditions. These include paralaryngeal discomfort or soreness of the throat from the increased effort of phonation Table 6.
Dryness of the throat is a common complaint in many types of voice disorder. Specifically, it can be due to medications such as diuretics or antimuscarinics, not drinking enough fluids, too much consumption of sugary or caffeine-containing foods and drinks, a persistent glottic gap or excessive autonomic stimulation secondary to anxiety, throat clearing, and mucus in the throat.
Based on the history, it should be possible to make a preliminary differential diagnosis. It is, however, virtually impossible in most cases to make a confident diagnosis without examining the larynx. Both oral rigid 70 or 90 degrees endoscopes and flexible or video nasendoscopes should be available and also a continuous halogen or xenon and stroboscopic light source and a digital imaging capture system for storage and replay. Nasendoscopes diameter 3.
Video nasendoscopes now allow much improved imaging with stroboscopy, which was previously limited with the fiberoptic nasendoscopes. High-speed digital imaging and videokymography can provide additional useful information when the vibratory patterns are complex, but are not in general use as yet. The choice of examination technique depends on the quality and availability of the equipment and the specific aim of the assessment Table 6. If a subtle abnormality of the mucosal wave is suspected, then good quality images using stroboscopy should be employed.
If a neurological or muscle tension problem is likely, then nasendoscopy with continuous light source is more useful. Inflammation can be assessed with either method. Sometimes both methods need to be employed and patient preference needs to be considered. There are patients who hate anything in their nose and others who have too strong gag reflexes to tolerate a rigid endoscope.
Rigid endoscopy can be used in many children from 5 years of age, although views are generally brief. Pediatric nasendoscopes diameter 2.
As part of the assessment, it is essential to check each anatomical site and subsite for the presence or absence of the four etiologic factors together with a series of phonatory and nonphonatory tasks Table 6. The phonatory tasks include checking the degree of closure of the vocal folds and supraglottic structures on phonation and the change in the mucosal wave with change in pitch and loudness. Palpation of the neck is also another key part of the assessment.
This is not only to detect enlarged lymph nodes or other structural abnormalities in the neck but also to detect evidence of muscle tension. In muscle tension dysphonia, the paralaryngeal and other anterior neck muscles are often chronically contracted and tender. The most consistently abnormal muscles are the cricothyroid, thyrohyoid, middle constrictor, and suprahyoid muscles.
In spite of a detailed history and examination, it is sometimes still not possible to make an accurate diagnosis. In these cases, further investigations may be required including acoustic and electrolaryngographic analysis of the voice, laryngeal electromyography, a diagnostic microlaryngoscopy, and high-definition computed tomography scan of the larynx.
Trials of medication and probe voice therapy are also useful and are covered in other chapters of the book. Once the main types of etiologic factor have been identified by detailed history, careful voice assessment, neck palpation, and laryngostroboscopic examination, it is then possible to be more precise in the diagnosis. Development and Validation of the Voice Handicap Index- Laryngoscope: 9 : My swallowing problem has caused me to lose weight. My swallowing problem interferes with my ability to go out for meals.
Swallowing liquids takes extra effort. Swallowing solids takes extra effort. Swallowing pills takes extra effort. Swallowing is painful. The pleasure of eating is affected by my swallowing. When I swallow food sticks in my throat. I cough when I eat.
Swallowing is stressful. Ann Otol Rhinol Laryngol , My cough is worse when I lie down. My coughing problem causes me to restrict my personal and social life.
I tend to avoid places because of my cough problem. I feel embarrassed because of my coughing problem. I run out of air when I cough. My coughing problem affects my voice.
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