Vocal Fremitus

Chest inspection, palpation, and auscultation constitute essential components of the physical examination in patients with respiratory disease. Palpation confirms findings observed during inspection and evaluates pleural and pulmonary parenchymal conditions through assessment of vocal fremitus. Tactile vocal fremitus is the palpation of the chest wall to detect variations in vibratory intensity generated by specific spoken words in a steady tone, providing information regarding underlying pulmonary pathology (see . Tactile Vocal Fremitus). Sound vibrations generated in the larynx during phonation are transmitted through the bronchi and lung parenchyma to the chest wall. The efficiency of this transmission depends on the physical properties of the underlying lung and pleural structures. Normal lung parenchyma consists of a mixture of air-filled alveoli and solid tissue. Air poorly conducts low-frequency sound, whereas denser media enhance transmission of these frequencies. Vocal fremitus decreases in conditions that alter the density or integrity of the lung parenchyma, pleura, or chest wall. Vocal fremitus is reduced in bronchial asthma, emphysema, and bronchial obstruction due to air trapping and decreased parenchymal density. Pleural effusion and pneumothorax similarly diminish transmission of low-frequency vibrations by introducing fluid or air into the pleural space. Attenuation of vocal fremitus also occurs in individuals with increased subcutaneous tissue, such as in obesity. Inflammation and consolidation increase tissue density, thereby enhancing the transmission of low-frequency sounds and vocal fremitus. Vocal resonance is the auscultatory counterpart of vocal fremitus, with characteristic changes observed in various pulmonary conditions. Bronchophony manifests as an increase in sound intensity over areas of consolidation. Whispering pectoriloquy occurs when whispered words, such as "one, two, three," are auscultated clearly over consolidated lung regions, reflecting the same underlying phenomenon as increased vocal fremitus. Egophony, or the "E to A" change, denotes a qualitative alteration in vocal tone in which specific frequencies transmitted through consolidated tissue distort the vowel "E" into a sound perceived as "A" or "AAAH." Additional types of fremitus include ronchial fremitus, corresponding to palpable rhonchi, and pleural fremitus, representing a palpable pleural rub.