1. Why High Opera Notes Need Over 1000 Vocal Cord Vibrations Per Second
Pitch is determined by "how many times per second" the sound source vibrates. Sound is produced when the two vocal cords in the throat vibrate as they are pushed by breath. The faster the vibration, the higher the pitch becomes [1]. The number of vibrations per second is called the fundamental frequency, measured in Hertz (Hz).
To sing the "Aria of the Queen of the Night," a soprano needs vibrations exceeding 1050 Hz, according to an article by the American Institute of Physics (AIP) [1]. In contrast, the typical speaking voice is about 125 Hz for men and about 210 Hz for women, according to encyclopedic references [2]. The 1050 Hz mark is about five times the frequency of a woman’s speaking voice (1050 ÷ 210).
What changes in the body allow humans to produce such fast vibrations?
2. How Vocal Cord Length Affects Pitch
The fundamental frequency of the vocal cords is affected by length, size, and tension. Generally, longer cords produce lower pitches, while tighter cords produce higher pitches [2]. Even in a physical model that treats the vocal cords like a string fixed at both ends, increasing the length lowers the fundamental frequency, while increasing the tension of the fibers raises it [3].
Adult vocal cords are said to be about 1.75–2.5 cm (0.7–1 inch) long for men, 1.25–1.75 cm (0.5–0.7 inches) for women, and 6–8 mm (0.2–0.3 inches) for newborns [2]. This difference in size is considered one reason why children’s voices are higher. In normal speech, the difference between men and women is about one octave [7].
According to explanations from the National Center for Voice and Speech (NCVS), the part that actually vibrates (the effective length) is on average about 60% longer in men than in women, which can explain nearly all of the difference between male and female voices [4]. This refers to the "length of the vibrating part," not the total length of the vocal cords. Note that values for vocal cord length vary slightly between sources due to differences in measurement methods, so we do not mix them in calculations.
Changes in length during male voice mutation are covered in a separate note. Here, we are interested in how the same person can produce both low and high voices. Can the length of the vocal cords be changed on the spot?
3. How the Cricothyroid Muscle Stretches the Vocal Cords to Raise Pitch
The muscle that stretches the vocal cords to increase tension is the cricothyroid muscle. This muscle is said to play a role in raising the frequency of the voice [5]. In studies of singers who have difficulty producing high pitches, the function of this muscle is also a focus of attention [5].
This is similar to how the pitch rises when you pull a rubber band. However, unlike a simple rubber band, vocal cords are made of multiple layers covered in mucous membrane.
The "thickness" and "mass" of the vocal cords are also mentioned in materials as factors affecting pitch. There are explanations from singing instructors that vocal cords become thinner when stretched for high notes, but we did not find primary sources that show numerical values for thickness alone. Therefore, we limit this to the statement that they are "said to become thinner."
So, how do the vocal cords actually move when a singer produces their highest voice?
4. What Happens in the Vocal Cords of Sopranos Singing the Whistle Voice
A research team from Germany and other countries collaborated with nine professional soprano singers to film their high notes (C6 ≒ 1047 Hz to G6 ≒ 1568 Hz) using an ultra-high-speed camera. The vocal cords were vibrating approximately 1000 to 1600 times per second, with the left and right sides colliding [6]. One cycle of vibration takes about 1 millisecond (1/1000th of a second).
This highest range has traditionally been called the "whistle register." However, the paper states that this name does not reflect the physical principles of a whistle in voice production. Instead, the sound is produced by the same mechanism as speech and other singing: the vocal cords vibrate and collide [6][1].
Calculations revealed the necessary conditions for these ultra-high notes. The model calculation required strong contraction of the cricothyroid muscle, stretching the vocal cords by about 50% (to about 1.5 times their original length), and high subglottal pressure (the pressure of air pushing up from below the vocal cords) [6]. The 50% figure is a value required by the computational model, not a measured value for all participants.
The subjects of this study were nine classical sopranos. This does not necessarily explain all ultra-high notes or singing styles.
5. How to Test Tension and Pitch Yourself with a Rubber Band
What you can do today: Hold a rubber band with both hands and gently flick it with your finger. Listen to the difference in pitch when it is loose versus when it is stretched. Do not point the rubber band at your face, and do not stretch it too much to prevent it from snapping and flying.
Another experiment: Lightly place your hand on your Adam’s apple area. Try changing from a low voice to a high voice gradually. See if you can feel the vibrations transmitted to the surface of your throat. Do not shout forcefully or continue until your throat hurts.
If you want to investigate further: Consult a specialist doctor in voice or a singing teacher for advice on how to produce sounds. This article is not medical advice.