14 Diagnosing Dysarthria in Adults chest or abdominal tumors. Diminishing the vital capacity of the lungs, bronchial tubes, and trachea lowers the pitch, reduces the volume of various sounds, deprives some sounds of the required tension (e.g. p, b), and shortens speech phrasing. One of the causes for hyperfunction of the respiratory system is damage to the upper motor neuron (e.g. in the case of amyotrophic lateral sclerosis [ALS] or damage to motor nuclei in the medulla), causing spasticity and desynchronization of respiratory muscles, manifested as explosive speech (Pruszewicz 1992). Distorted phonation may result from pathological position of the vocal folds due to damaged nerves, muscles, or neuromuscular junctions, as well as due to tumors, edemas, or inflammatory conditions in the relevant areas. Phonatory hypofunction occurs with increased adduction of the vocal folds, which leads to heightened pitch, stifled and strangled vocalization. Such disorders often accompany pseudobulbar palsy, dystonia, and cerebellum diseases. In phonation disorders of the mixed type, almost all of the above-mentioned signs are attested, which leads to the production of harsh and hoarse sounds. This may be related to structural damages to vocal folds, such as inflammatory conditions, polyps, and tumors (Pruszewicz 1992). Distorted phonation may also stem from structural damage to organs located above the larynx, causing resonance disorders, such as h y p e r - or h y p o n a s a l i t y, which affect articulation. Excessive (open) nasality or hypernasality is associated with impaired functions of the pharyngeal-palatal region or the soft palate and involves uncontrolled airflow through the nasal cavity during speaking. Hyponasality or closed nasality, on the other hand, is caused by the malfunctioning of nostrils or by opening of the pharyngeal-palatal region. In this impairment, acoustic energy passes through the lips, rendering nasal consonants such as m, n, similar in articulation to the non-nasal b, d. Vowels produced in hyponasality are stifled and dull. General articulatory disorders due to neurological diseases lead to speech distortions: omissions, alternations, sound substitutions or additions. Articulatory disorders never occur in isolation. Patients with all types of dysarthria also exhibit prosodic disorders. In h y p e r p r o s o d i c conditions, we observe increased abruptness of speech and height of pitch, similar to Broca aphasia and manic conditions. In h yp o p r o s o d i c disorders, expression, intensity, and pitch variation are significantly diminished, while speech rhythm may be completely lost. Such disorders typically accompany Parkinsonism or damages to the right
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