While asthma and nasal allergies are medical conditions of the respiratory tract, they may play a role in childhood communication disorders. Up to 50% of children with speech and voice disorders also have asthma, allergic rhinitis, or both (Baker, Baker, & Le, 1982; Keating, Turrell, & Ozanne, 2001). The prevalence of speech issues in children without these respiratory illnesses is significantly lower. The frequent co-occurrence of bronchial asthma and allergic rhinitis results in an interplay of symptoms that may contribute to communication disorders including deficits in articulation, voice, and even language acquisition and reading.
1. Mouth breathing, around the clock or only during sleep, is a common sign of respiratory illness. While it helps compensate because air intake through the nose is blocked when the nose is stuffy or the lungs are “tight” it can aggravate asthma and allergies. Breathing through the nose filters and warms the air, preventing irritation to delicate respiratory tissue. Moreover, as mouth breathing aggravates respiratory dysfunction, it also damages the structure and function of the key players in speech articulation: the tongue, lips, and mandible. A habitually open-mouthed posture leads to a protruding tongue, lips that do not contact at rest, and a slack lower jaw. In these relaxed, floppy postures, the articulators cannot move quickly and accurately from one speech position to another. Try saying the Pledge of Allegiance with your tongue hanging out; you may sound positively unpatriotic. The moving parts must maintain tone to support rapid motion between precise positions in order to form the full range of sounds in distinct, articulate speech.
2. Poor breath control is another facet of respiratory illness that affects communication. Bronchial asthma and nasal allergies can cause shortness of breath and shallow breathing (from the chest or shoulder muscles rather than the diaphragm). In turn, lack of breath support can result in low voice volume, since loudness is directly related to the amount of air escaping from the lungs. Poor voice quality (hoarseness, roughness, or a strained/strident voice) results from inadequate or badly controlled airflow. Speech prosody (rhythm and intonation) also depends on exhalation: we must budget airflow to control the number of words we say per breath and the tone and loudness of particular words in a sentence (for emphasis). Breathe out so that your lungs feel empty, and, before inhaling again, say your name and address; can you get the whole thing out with the same power? Without breath support, you can’t talk for long, and what you do say will sound low and raspy.
3. Airway inflammation caused by allergies and asthma can hurt the sound quality of the voice. The vocal cords (a.k.a. vocal folds) cover the larynx, the top part of the trachea (airway tube to the lungs). These mucus-covered muscular bands are the vibrating “strings” that produce voice sound, which is then filtered and shaped by the resonating cavities of the throat, nose, and mouth. Inflammation along the passageways from the nose down to the larynx can impair vocal quality. Bronchial asthma, labored breathing and wheezing, and allergies can also cause sore throat and inflammation around the vocal cords. Swollen, inflamed cords don’t vibrate efficiently and can make the voice sound hoarse or scratchy. Nasal congestion due to allergies can lead to hyponasality–how you sound when you have cold–a resonance disorder. Since certain sounds in English (n, m, and –ng) depend on directing airflow through the nose, nasal congestion can also cause misarticulation (think of the child with a stuffy nose who asks her “bobby” for some Kleenex).