Term Category: Voice Science
The Hering-Breuer Reflex, discovered by physiologists Ewald Hering and Josef Breuer in the 19th century, is a reflex mechanism that plays a critical role in regulating the rhythm of breathing. It is essentially a protective reflex that prevents over-inflation of the lungs.
Definition and Mechanism:
The Hering-Breuer Reflex is initiated by stretch receptors located within the smooth muscles of the bronchi and bronchioles in the lungs. These receptors are sensitive to the stretching of the lung tissue caused by the lungs filling with air. When the lungs inflate to a certain volume, these receptors send inhibitory signals via the vagus nerve to the brainstem's respiratory center. This action triggers the end of the inhalation phase and promotes the start of exhalation, thereby preventing over-expansion of the lungs which could potentially lead to lung damage.
There are two components of the Hering-Breuer Reflex:
- Inflation Reflex (Hering-Breuer Inspiration Reflex): This inhibits inspiratory muscles to stop inhalation, thus avoiding over-inflation.
- Deflation Reflex: Less well understood, it supposedly encourages the onset of inspiration, preventing lung collapse by maintaining a certain minimal volume of air in the lungs.
Impact on Singing and Singing Teaching:
In singing and teaching, breath control is a fundamental aspect of technique, and understanding the Hering-Breuer Reflex can have practical implications.
- Breath Management: Singers must learn to manage their breath efficiently to sustain phrases and control dynamics. Recognizing the body's natural impulse to exhale when the lungs reach maximum inflation can help singers plan their breaths to coincide with the natural rhythm of their body, avoiding the tension that might arise from resisting this reflex. During the majority of singing there is no reason to reach this state of maximal inflation.
- Phrasing: Understanding this reflex allows singers and teachers to structure musical phrases that work with, rather than against, the body’s natural breathing reflexes. This could mean breaking longer phrases into shorter segments that align with comfortable breath cycles.
- Breathing Exercises: Singing teachers may incorporate specific breathing exercises into training to enhance singers’ control over their inhalation and exhalation phases. By doing so, they can train singers to gently extend the capacity and flexibility of their lungs, improving their ability to control the timing of breath release for optimal singing performance.
- Preventing Vocal Fatigue: Overriding the Hering-Breuer Reflex consistently can lead to increased tension in the muscles of respiration, which may contribute to vocal fatigue. Singers need to develop a breathing technique that acknowledges the body's cues for inhalation and exhalation to maintain vocal health.
- Relaxation and Support: A singing technique that respects the natural ebb and flow of the breath cycle will lead to a more relaxed posture and support system. Teachers often stress the importance of a relaxed approach to inhalation, which can be facilitated by an understanding of the Hering-Breuer Reflex and its role in signaling the end of the inhalation phase.