Vocal Cords: The Science and Symphony of Sound Production

boy shouting

The human voice is an incredible instrument that conveys a spectrum of emotions and sounds. As singers, we focus a lot on technique and expression, but how often do we consider the mechanics behind our art? At the core of our vocal abilities are the vocal cords. You might also come across them being referred to as “vocal folds” or, mistakenly, as “vocal chords.”

In this article, we’re diving into the world of the vocal cords. We’ll break down their anatomy, explore how they produce sound, discuss pitch modulation, and look at how they change over time. It’s a mix of art and science, and by the end, you’ll have a clearer understanding of the foundation of your voice.

What are Vocal Cords?

The human body is teeming with fascinating components, many of which we may not give a second thought to until we truly understand their significance. One such component, particularly crucial for us vocalists, are the vocal cords.

Definition and Introduction to Vocal Cords

Vocal cords, sometimes referred to as “vocal folds”, are a pair of muscle-controlled structures located within the larynx, or voice box, in our throat. These are not cords in the sense of strings or ropes; instead, they resemble two flexible, layered folds made up of muscle, ligament, and a mucous membrane.

Their Role in Voice and Sound Production

Every time we speak, sing, or even hum, our vocal cords come into play. When air from our lungs rushes up through the trachea, it causes these cords to vibrate. This vibration turns the air into sound waves. The pitch of the sound is largely determined by the tension and length of the vocal cords: when they’re tighter and shorter, we produce higher-pitched sounds, and when they’re more relaxed and longer, we generate lower tones. The resonance chambers in our face and head, like our mouth, nasal passages, and sinuses, then shape this sound to produce the unique timbre of our voice.

Where are the Vocal Cords Located?

The larynx, commonly referred to as the “voice box”, serves as the home for the vocal cords. Located in the neck, the larynx sits just above the trachea (windpipe) and below the pharynx (the part of the throat behind the mouth and nasal cavity). If you’ve ever felt a protrusion on the front of a man’s neck, you’ve touched the Adam’s apple or the thyroid cartilage, which is the most prominent part of the larynx.

The Vocal Tract and the Role of Vocal Cords

The vocal tract is like a musical instrument’s body, shaping and amplifying the sounds produced by the vocal cords. Starting from the larynx, it extends upward through the pharynx, the oral cavity (mouth), and finally, out through the nasal or oral passages. The vocal cords sit at the beginning of this tract, acting as the primary sound source. As sound waves travel through the vocal tract, various structures, like the tongue, soft palate, and lips, modify these sounds to produce the distinct voice we recognize.

In simple terms, think of the vocal cords as the strings of a guitar and the vocal tract as the body of the guitar. Just as the strings produce the raw sound that the body then shapes and amplifies, the vocal cords generate sound that the vocal tract then modifies, allowing us to sing, speak, and communicate in our unique voices.

vocal cords / vocal folds

Anatomy of the Vocal Cords

Diving deeper into the intricacies of our vocal apparatus, it’s vital to understand that there’s more than meets the eye (or rather, the ear) when it comes to the vocal cords. Akin to the many layers of an onion, the voice box houses both true and false vocal folds, each with its distinct structure and function.

True Vocal Folds (TVFs)

Structure and Material Composition

The True Vocal Folds are multi-layered structures that primarily comprise five layers: the epithelium (outermost layer), the superficial lamina propria, the intermediate lamina propria, the deep lamina propria, and the thyroarytenoid muscle. This complex layering gives the TVFs their flexibility and resilience. The outermost layer is mucosal, allowing for smooth vibration, while the inner layers, especially the muscle, provide the ability to change shape and tension.

Role in Sound Production

The TVFs are the primary actors in voice production. As air from the lungs passes through the trachea and reaches the larynx, the TVFs come together. The air pressure makes them vibrate, turning airflow into sound waves. Adjustments in their length and tension, controlled by surrounding muscles, allow us to modulate pitch and intensity.

False Vocal Folds (FVFs)

Structural Differences from TVFs

Situated just above the true vocal folds, the False Vocal Folds have a less intricate structure. They lack the muscle layer present in TVFs, primarily consisting of mucus-covered connective tissue. This makes them less flexible and less mobile than their counterparts.

TVF Function and Why They Don’t Produce Sound Directly

While the TVFs are the star players in sound production, the FVFs play a more supporting role. They assist in closing off the airway during swallowing, ensuring that food and liquids don’t enter our trachea. Given their structure, they aren’t equipped to vibrate in the same finely controlled manner as the TVFs. Hence, they don’t contribute directly to sound production. Instead, their primary roles revolve around protecting and aiding certain respiratory functions.

How Do Vocal Cords Produce Sound?

Sound production within the human body is a fascinating interplay of mechanics and acoustics. The vocal cords, acting as the initial sound generator, go through intricate motions that give life to the raw sounds which then travel through our vocal tract. Let’s break down this process step by step.

Closed Phase and Open Phase:

  • Closed Phase: This is when the vocal cords come together, effectively blocking the passage of air from the lungs. No air can pass through, and pressure builds up beneath the cords.
  • Open Phase: As the pressure beneath the vocal cords becomes too high, they are forced apart, letting the air rush through. This rapid release causes them to vibrate, producing sound waves. Once the pressure is reduced, the elastic properties of the vocal cords cause them to return to their original position, initiating the closed phase again. This cycle of opening and closing happens hundreds of times per second, depending on the pitch being produced.

Air Pressure and Vibration

The process begins when we exhale, pushing air from the lungs upward. As this air reaches the closed vocal cords, it builds up pressure beneath them, eventually leading to the open phase. This continuous cycle of pressure building and release, in conjunction with the elastic nature of the vocal cords, causes a repetitive vibration. This vibration, at its essence, is what produces the raw sound of our voice.

Role of Resonance in the Vocal Tract:

Imagine singing into an empty room versus singing into a well-designed auditorium; the difference in sound quality is largely due to resonance. Once the raw sound waves are produced by the vibrating vocal cords, they travel through the vocal tract. As they navigate through this “resonating chamber”, comprising the throat, mouth, and nasal passages, they interact with these structures. These interactions amplify certain frequencies and dampen others. The shape and size of the vocal tract, along with movements of the tongue, lips, and soft palate, adjust this resonance, producing the wide range of tones and timbres that make up our unique voices.

Adjusting Pitch

Every time a singer effortlessly transitions from a deep, rich low note to a piercing high one, they’re leveraging the incredible adaptability of their vocal cords. But what’s the science behind these variations in pitch?

Introduction to Pitch and Frequency

At its core, pitch is our auditory perception of frequency. Frequency, measured in Hertz (Hz), indicates the number of vibrations (or cycles) the vocal cords complete in a second. A high pitch corresponds to a high frequency, meaning the vocal cords vibrate rapidly. Conversely, a low pitch indicates a slower vibration and lower frequency.

How Tension and Length of the Vocal Cords Influence Pitch:

  • Tension: Just like the strings on a musical instrument, increasing the tension on the vocal cords raises the pitch. This is because tighter cords vibrate at a higher frequency when air passes through them. The vocal cord muscles, particularly the cricothyroid muscle, play a pivotal role in adjusting this tension. By contracting and relaxing, these muscles alter the tension of the vocal cords, allowing singers to produce a variety of pitches.
  • Length: The length of the vocal cords also plays a crucial role. When the cords are elongated or stretched, they produce higher pitches, and when shortened, they produce lower pitches. This is achieved by the movement of the thyroid and arytenoid cartilages, which adjust the length of the vocal cords.

Which Parts of the Folds are Used in Various Pitches:

The entire length of the vocal cords does not always vibrate uniformly. The portion that vibrates can change based on the pitch:

  • Low Pitches: For deeper, lower pitches, more of the vocal cord length tends to vibrate. This is because the cords are more relaxed and have a larger mass that moves freely.
  • High Pitches: When hitting high notes, only a smaller portion, typically towards the inner edges of the vocal cords, vibrates. This is due to the increased tension and reduced mass that’s free to vibrate.
  • Understanding these nuances not only showcases the vocal cords’ versatility but also highlights the precision and control singers must develop to master their craft.

Other Functions of the Vocal Cords

While the vocal cords are celebrated for their pivotal role in sound production, they also serve other vital functions in our daily lives, many of which go unnoticed but are essential for our safety and comfort.

Protection: Preventing Food and Liquids from Entering the Trachea

One of the primary non-vocal functions of the vocal cords is to act as a protective barrier for the trachea and lungs. When we swallow, the vocal cords come together, sealing off the airway. This action ensures that food and liquids are directed down the esophagus and into the stomach, rather than mistakenly entering the trachea. This protective reflex is crucial for preventing choking and aspiration, which could lead to serious lung infections or other complications.

Breath Control: Assisting in Breath Regulation

The vocal cords play a subtle yet significant role in regulating our breath. Whether you’re holding your breath underwater or stabilizing your breath while aiming for a target, the vocal cords come together to resist the flow of air out of the lungs. Additionally, during activities that require exertion, like lifting heavy objects, the vocal cords can momentarily close, building up intra-abdominal pressure that provides added support and stability to the core muscles.

Contribution to the Valsalva Maneuver: Equalizing Ear Pressure

If you’ve ever tried to pop your ears during a flight or while diving deep underwater, you’ve likely employed the Valsalva manoeuvre, even if unknowingly. During this action, we attempt to forcibly exhale while keeping the mouth and nose closed. This process increases the pressure in the chest and can help equalize the pressure in the middle ear. The vocal cords contribute by sealing the airway, allowing the buildup of pressure necessary for the manoeuvre to be effective.

  • While their role in voice generation often takes centre stage, understanding these additional functions of the vocal cords paints a fuller picture of their importance in our overall health and well-being.

Age and Vocal Cords

Much like every other part of our body, our vocal cords are not immune to the passage of time. They undergo numerous transformations from the moment we utter our first cry to the soft-spoken words of our twilight years. But how exactly do these changes manifest, and what impact do they have on our voice?

How Vocal Cords Evolve from Infancy to Old Age:

  • Infancy and Childhood: Babies start with tiny, delicate vocal cords, giving them their characteristic high-pitched cry. As children grow, their vocal cords lengthen and thicken, resulting in a gradual lowering of voice pitch. This process continues until adolescence.
  • Adolescence: Puberty brings about significant changes to the vocal cords, especially pronounced in males. This is the phase when the “voice breaking” phenomenon occurs, leading to the deepening of the voice. For females, while the change is less drastic, there’s still a noticeable maturation in voice quality.
  • Adulthood to Middle Age: During these years, the vocal cords are usually at their prime in terms of strength and elasticity. However, with constant use and potential strain (especially for professional singers or speakers), there might be some wear and tear.
  • Old Age: As we advance in years, the vocal cords can lose some of their elasticity, becoming less flexible and more stiff. There’s also a reduction in the natural lubrication, which can impact their vibrational qualities.

Impact of Age on Texture, Flexibility, and Thickness:

Over time, just like skin, the vocal cords can develop irregularities in their texture. This can be due to nodules, polyps, or just general wear. Their flexibility diminishes as the elastin fibres degrade and collagen increases, making them less pliable. Moreover, they might become thinner or, in some cases, develop a certain level of atrophy.

Implications of these Changes on Voice Range and Quality:

With age, the voice can become:

  • Breathier: Due to the reduced closure of the vocal cords.
  • Less Powerful: As the muscle tone and lung capacity decrease.
  • Narrower in Range: The reduced flexibility of the cords might limit the ability to hit extreme high or low notes.
  • Shakier or Tremulous: This is often a result of reduced muscle coordination.

However, it’s worth noting that, like all aspects of ageing, changes in the voice vary from person to person. Factors like genetics, overall health, and how the voice has been used throughout life (e.g., a career in singing) can all influence these outcomes.

Male vs Female Vocal Folds

Every time a baritone voice harmonizes with a soprano in a song, it’s a delightful testament to the differences between male and female vocal cords. While both sets of vocal cords function in the same fundamental way, there are distinct anatomical differences and resulting tonal variations between the genders. Let’s explore these distinctions further.

Anatomical Differences Between Genders:

  • Size: Male vocal cords are generally longer and thicker than their female counterparts. Adult male vocal cords typically measure between 17 to 25 mm in length, while female vocal cords measure approximately 12.5 to 17.5 mm.
  • Larynx Size and Position: The male larynx, or “Adam’s apple”, is usually larger and more prominent than in females. This is because the laryngeal prominence (the front part of the voice box) is more pronounced in males. Additionally, the male larynx tends to sit lower in the neck compared to the female larynx.

Why Male Voices are Typically Deeper and Female Voices are Higher:

The depth or pitch of a voice is largely determined by the length and thickness of the vocal cords. Since male vocal cords are longer and thicker, they vibrate at a slower frequency, producing a deeper sound. In contrast, the shorter and thinner female vocal cords vibrate at a higher frequency, yielding a higher-pitched voice.

The Transitional Phase During Adolescence and Its Effects on the Male Voice:

Puberty heralds significant changes in the vocal cords, especially for young males:

  • Voice Deepening: As a boy progresses through puberty, testosterone stimulates the growth of the vocal cords, making them longer and thicker. This results in the deepening of the voice, a phenomenon commonly referred to as the voice “breaking” or “cracking.”
  • Voice Instability: During this transitional period, the voice might exhibit unpredictability. It can fluctuate between high and low pitches, sometimes suddenly and without warning. This is because the vocal cords are growing rapidly, and the laryngeal muscles need time to adjust to their new size.
  • Settling of Voice: By the end of puberty, the male voice usually stabilizes to its adult timbre, with the vocal cords reaching their full length and thickness.

Vocal Cord Health

A finely-tuned musical instrument sounds best when it’s well-maintained and cared for, and our vocal cords are no exception. Both singers and everyday speakers rely on their vocal cords to communicate, express emotion, and in some cases, earn a living. Thus, understanding the nuances of vocal cord health is crucial.

Importance of Maintaining Vocal Cord Health for Both Singers and Non-Singers:

Your voice is an integral part of your identity. Singers, of course, depend heavily on their vocal cords for their art and livelihood, but non-singers too utilize their voices daily, whether it’s for work presentations, teaching, or simply conversing with loved ones. Maintaining vocal cord health ensures clarity of speech, longevity of voice use, and prevention of potential vocal issues.

Common Issues: Nodules, Polyps, and Strain:

  • Nodules: These are small, benign growths on the vocal cords, often resulting from vocal strain or overuse. They can make the voice sound raspy or breathy.
  • Polyps: Similar to nodules but usually larger and stemming from longer-term strain or injury. Polyps can cause a wider range of vocal disruptions, including hoarseness and breathiness.
  • Strain:┬áConstant shouting, excessive coughing, or prolonged periods of singing without adequate rest can lead to vocal strain. Symptoms include a feeling of tightness, fatigue, and sometimes pain after voice use.

Tips for Vocal Cord Care:

  • Hydration: Drinking enough water keeps the vocal cords moist and flexible, reducing the risk of damage.
  • Avoid Smoking: Smoke irritates the vocal cords, making them swell, which can lead to chronic hoarseness and other voice issues.
  • Warm-Up Before Singing: Just like athletes stretch before a game, singers should warm up their vocal cords to prepare them for intense use.
  • Limit Loud Talking or Singing: Constantly raising your voice or singing at high volumes can lead to strain. Use microphones when necessary and take voice breaks.
  • Rest: If you’ve been using your voice heavily, allow time for your vocal cords to recover. Silence can be therapeutic.

When to Seek Medical or Professional Intervention:

  • Any persistent change in voice quality, prolonged hoarseness, pain, or any other unusual symptom warrants attention. It’s essential to consult with an Ear, Nose, and Throat (ENT) specialist or a voice therapist to assess the situation and provide guidance. Early intervention can prevent minor issues from escalating into more severe conditions.

In Harmony with Our Vocal Cords

Our vocal cords truly are marvels of human anatomy. While they’re often celebrated for their role in producing melodious tunes or powerful speeches, their multifunctionality extends far beyond these roles. From safeguarding our airways when we eat to assisting in regulating airflow during physical exertion, these tiny structures work tirelessly behind the scenes in myriad ways most of us rarely ponder.

But like any precious asset, the vocal cords require diligent care. Just as a musician cherishes and maintains their instrument, each of us, singer or not, must respect and nurture our vocal cords. Their health directly impacts the quality, clarity, and longevity of our voice, influencing not just our ability to sing or speak, but also our daily communications and expressions.

In our journey of voice, from the innocent babblings of infancy to the matured conversations of old age, our vocal cords stand by us, adapting and evolving. It’s our responsibility to protect and cherish them in return, ensuring that every note sung and every word spoken is imbued with the richness they deserve. So, here’s to our vocal cords – the unsung heroes of our daily symphony. Let’s pledge to keep them in tune, always.