Inspiratory Reserve Volume – Voice Science

Definition

Inspiratory reserve volume (IRV) is the maximum additional volume of air that can be inhaled beyond a normal tidal breath—the respiratory reservoir that professional singers exploit to achieve sustained phonation and extended phrase lengths. Typical values range from 2.5–3.25 liters in adult males and 1.7–2.5 liters in adult females, constituting approximately 50–60% of vital capacity. John Hutchinson designated this volume as “complemental air” in his foundational 1846 spirometry paper. IRV is calculated mathematically as inspiratory capacity minus tidal volume (IRV = IC − TV).

Context

Relevance to Voice Production

Professional classical singers initiate phrases at 70–100% of vital capacity—deep within the IRV domain—compared to 60% VC for conversational speech or 40% VC for quiet breathing. This strategic engagement of IRV provides the respiratory foundation for sustained phonation. Thomasson and Sundberg (1997) documented that operatic singers terminate phrases at approximately 30% VC, utilizing a lung volume range far exceeding speech requirements.

The critical distinction is physiological: at high lung volumes within the IRV range, passive expiratory recoil forces can reach approximately 30 cmH₂O—often exceeding the pressure needed for singing. Singers must therefore employ inspiratory muscle “support” to control the rate of lung deflation and maintain appropriate subglottal pressure.

Key Research Finding

Research consistently demonstrates that trained singers do not possess significantly greater static lung volumes than non-singers. Gould’s 1960 benchmark study and Schorr-Lesnick et al. (1985) found no significant spirometric differences between singers and controls. The benefit derives from how volumes are used, not from possessing greater capacity.

Scientific Basis

Physiological Generation

IRV access requires recruitment beyond the primary respiratory muscles used in quiet tidal breathing:

• Diaphragm: Principal inspiratory muscle; excursion increases from 1–2 cm (tidal) to up to 10 cm (maximal inspiration)
• External intercostals: Elevate rib cage in “bucket handle” and “pump handle” motions
• Accessory muscles: [[Scalenes, sternocleidomastoid, pectoralis major and pectoralis minor.

Lung compliance—the change in volume per unit change in transpulmonary pressure—depends on elastin/collagen fiber networks and surfactant production. These values decline with age: vital capacity decreases approximately 200 mL per decade after age 30.

Pressure-Volume Mechanics

At functional residual capacity (approximately 38% VC), lung and chest wall elastic recoil forces precisely balance. Above this equilibrium point—where singers primarily operate—the combined recoil is inwardly directed. Iwarsson, Thomasson, and Sundberg (1998) demonstrated that with decreasing lung volume, closed quotient increased while subglottal pressure and glottal leakage decreased, confirming that lung volume position directly affects phonation efficiency.

Pedagogical Considerations

The Appoggio Connection

The Appoggio technique directly involves IRV utilization through balanced opposition between inspiratory and expiratory forces. Manuel Garcia described this as the “lutte vocale” (vocal struggle)—respiratory muscles striving to retain air while opposing expiratory muscles. The main task is to delay the rise of the diaphragm, maintaining high lung volumes and using sustained inspiratory muscle activity to control subglottal pressure across the phrase.

Evidence-Based Principles

Watson and Hixon (1985) found that “subjects’ descriptions of how they thought they breathed during singing bore little correspondence to how they actually breathed”—a finding arguing against imposing uniform breathing patterns. Evidence supports targeting initiation at 70–80% VC and termination at 30–50% VC.

Respiratory Muscle Training

Yilmaz et al. (2025) demonstrated that inspiratory muscle warm-up at 40% maximal inspiratory pressure produced significant acute improvements: maximum phonation time increased 21%, high-pitch note duration improved 35%, and perceived exertion decreased 12%.

Related Terms

Also known as: IRV, Complemental air (historical)

See also: Lung Capacity (parent concept), Vital Capacity, Inspiratory Capacity (IRV + TV), Tidal Volume, Expiratory Reserve Volume (complementary volume below tidal), Appoggio (technique governing IRV utilization)

References

Gould, Wilbur J. 1960. “Respiratory and Phonatory Function of the Larynx.” Annals of Otology, Rhinology & Laryngology 69: 1156–1176.

Hutchinson, John. 1846. “On the Capacity of the Lungs, and on the Respiratory Functions.” Medico-Chirurgical Transactions 29: 137–252.

Iwarsson, Jenny, Monica Thomasson, and Johan Sundberg. 1998. “Effects of Lung Volume on the Glottal Voice Source.” Journal of Voice 12(4): 424–433. https://doi.org/10.1016/S0892-1997(98)80051-9.

Thomasson, Monica, and Johan Sundberg. 1997. “Consistency of Phonatory Breathing Patterns in Professional Operatic Singers.” Journal of Voice 11(4): 373–383. https://doi.org/10.1016/S0892-1997(97)80033-8.

Watson, Peter J., and Thomas J. Hixon. 1985. “Respiratory Kinematics in Classical (Opera) Singers.” Journal of Speech and Hearing Research 28(1): 104–122. https://doi.org/10.1044/jshr.2801.104.

Yilmaz, Çetin, et al. 2025. “Acute Effects of Inspiratory Muscle Warm-Up on Vocal Performance in Opera Singers.” Journal of Voice. Advance online publication. https://doi.org/10.1016/j.jvoice.2024.12.029.