Voice

The human voice is the sound produced by the vocal folds in the larynx vibrating as air passes through them.

This simple biological mechanism allows us to speak, sing, yell, and express ourselves in endless ways. For music producers and audio engineers, understanding the anatomy and acoustics of the voice is crucial for recording, processing, and mixing vocals effectively.

This article will provide a comprehensive overview of the building blocks of the human voice, from the lungs providing airflow to the vocal tract shaping that airflow into speech and song. We’ll examine the muscular control and resonance properties that allow us to change pitch, timbre, and loudness. Vocal registers like chest voice and falsetto along with voice modulation will be demystified.

You’ll learn how factors like physiology, genetics, and vocal health impact the voice and how to coach singers to get the best takes. We’ll also explore some audio engineering applications like using pitch correction, compression, reverb, and EQ to enhance vocals in a mix.

By the end of this guide, you’ll understand exactly what makes each voice unique and how to work with singers to capture their best vocal performances. Whether you’re recording your first album or working with Grammy winners, this deep dive into voice anatomy, physiology, and technique will give you newfound confidence for your next vocal tracking or mixing session.

The Anatomy of the Voice

The human voice is an intricate instrument consisting of several parts working together to produce sound. To understand vocal anatomy, we’ll start from the bottom up, looking at how airflow is created and then modified on its journey from the lungs to the outside world.

The Lungs

The engine that powers the human voice starts with the lungs. As the main respiratory organs, the lungs provide the steady stream of air that will eventually be transformed into audible vocal sound.

When we inhale, the diaphragm contracts and pulls downward, while the external intercostal muscles lift the ribcage outward. This expansion creates negative pressure that draws air into the lungs. Oxygen is absorbed into the bloodstream while waste gases like carbon dioxide are exhaled.

During normal breathing, only a small amount of lung volume is used. But for singing or speaking loudly and at length, greater lung capacity and control is required. Vocalists learn to fully engage the diaphragm and ribcage to maximize the amount of air inhaled and exhaled.

As the lungs fill up, their elastic tissue stretches to hold more volume. When exhaling to speak or sing, the diaphragm and intercostals contract against this elastic recoil to steadily expel air at subglottal pressure through the trachea.

The right amount of lung pressure is critical for vocal production. Too little pressure results in weak, breathy tone as insufficient airflow reaches the larynx. Too much pressure can also impair voice control and pitch stability.

Larger, more trained lungs allow greater power and sustain. An untrained person may have a vital lung capacity of 4 liters, able to exhale 1 liter per second to produce sound. In contrast, an opera singer can inhale over 5 liters and maintain smooth, steady exhalation of up to 3 liters per second, enabling more resonant tone that projects effortlessly.

Proper breathing technique is thus the foundation for vocal power, stamina and volume. Learning to efficiently harness available lung capacity gives singers better control and endurance.

The Larynx

The lungs may provide the power, but the sound of your voice is created in the larynx or voice box located in the throat. This complex structure houses the vocal folds which vibrate to turn airflow into audible pulses.

The largest cartilage is the shield-shaped thyroid, front and center in the neck. Attached in back are the paired arytenoid cartilages that pivot to bring the vocal folds together or apart. The cricoid cartilage forms a ring below them.

Spanning between these cartilages are the vocal ligaments and folds. These multilayered mucosal tissue membranes can stretch, contract, and vibrate rapidly.

In men, the larger larynx houses longer, thicker vocal folds around 20mm long. In women, the smaller larynx results in vocal folds 12-17mm long. This difference in vocal fold size produces the characteristic pitch distinction between male and female voices.

During speech and singing, muscles pull the arytenoid cartilages forward, bringing the vocal folds close together. Air pressure from the lungs builds below them until they are blown apart, allowing the air to expel. This creates a tiny puff of air that travels up through the vocal tract.

The folds then come back together due to their elasticity, trapping the air below and repeating the process. This rapid opening and closing is called phonation, creating pulses of air that form the basis of vocal sound.

By controlling muscle tension and airflow, singers can vary fold tension, position, and vibration rate to manipulate pitch, volume, and timbre. The intrinsic muscles of the larynx are exceptionally fast compared to other muscle types, allowing rapid pitch and volume modulation.

The Vocal Tract

Once air pulses are created at the larynx, they travel upwards through the vocal tract. This consists of the pharynx, mouth, and sometimes nose. The size and shape of these cavities can be changed by moving various articulators to sculpt the raw laryngeal vibration into recognizable speech and song.

The first articulator is the tongue, creating constrictions that enhance certain frequencies called formants. Vowel sounds are defined by the positioning of the tongue body high/low and front/back in the oral cavity. This filters the source signal from the larynx to produce distinguisable vowels like ah, ee, oo.

The lips also shape vowel sounds through rounding and spreading. Lip protrusion enlarges the mouth, stretching out the vocal tract to lower formants. Spread lips do the opposite, raising formants.

Consonants rely on sharper constrictions created by tongue tip/blade against the teeth and hard palate. Fricatives like s,z,f,v involve turbulent airflow through a narrow opening. Plosives like p,b,t,d use complete closures, building pressure that is explosively released.

The soft palate or velum seals off the nasal cavity for most speech, but can be lowered to produce nasal vowels and consonants like m,n,ng. The jaw opening also affects tract size, with a larger jaw lowering the frequency of formants.

Singers exercise great control over all these articulators to shape their unique vocal timbre. They learn to consciously adjust the vocal tract geometry to hit resonances that amplify and enrich the harmonic content of each note.

Pitch and Harmonics

The pitch of the voice, whether speaking or singing, depends primarily on the vibration rate of the vocal folds. This in turn is determined by their length, tension, and mass.

Longer, thicker, and looser folds will vibrate more slowly, producing a lower pitched voice. Shorter, thinner, and tenser folds will vibrate more rapidly, resulting in a higher pitched voice.

This basic anatomy is why adult males generally have lower pitched voices than adult females and children. Testosterone thickens the male vocal folds during puberty, dropping pitch an octave or more. Longer adult male folds vibrate around 100 times a second, while shorter female folds vibrate closer to 200 times a second.

In singing, vocal pitch can be consciously controlled by increasing fold tension and thinning to raise pitch or doing the opposite to lower it. But every voice has its comfortable pitch range determined by anatomy.

The vibration rate of the vocal folds produces a repeating waveform that forms the fundamental frequency. This basic pitch is then embellished with harmonics or overtones spaced at multiples of the fundamental.

The relative strength of these harmonics gives voice its timbre. A bright voice has robust higher harmonics while a mellow voice has weaker upper harmonics.

Together, the pitch and timbre create the distinctive quality of each voice. This stems from the larynx producing source vibration, filtered through the personalized resonance properties of each vocal tract.

Voice Modulation

The human voice is incredibly versatile thanks to our ability to consciously control and modulate it. While anatomy defines the baseline pitch and timbre, there is considerable room for voluntary modification. This section examines how vocal fold movement, breathing, and articulation can be adjusted to vary different parameters of the voice.

Physiology of Voice Modulation

The primary parameters of vocal sound – pitch, loudness, and tone quality – stem from physiological factors under deliberate muscular control. Let’s examine how singers and speakers consciously modulate their voice anatomy to vary these attributes.

Pitch control relies on regulating vocal fold tension, mass, and vibration rate. Muscles in the larynx stretch the folds to raise pitch or allow them to thicken and loosen to lower pitch. Vocalists practice exercises to develop an even scale with no sudden jumps between pitches.

Loudness is increased by greater subglottal pressure forcing the vocal folds apart. This is achieved by expelling more air from the lungs by engaging the diaphragm and intercostals. Fold adduction and closure speed also affects volume.

Timbre is shaped by the vocal tract resonances highlighted or attenuated as articulator positions are adjusted. The throat space, tongue, lips, jaw, and soft palate all modify harmonic content.

Kids aren’t born with voluntary control over their vocal anatomy. They can cry, laugh, and babble, but must learn to deliberately manipulate their voice for clear speech through years of listening, experimentation and mimicry.

Initially, speech muscle coordination is erratic as the child brain calibrates auditory goals to the motor skills producing them. But great strides are made between ages 1-3 as they master isolating and contracting specific muscle groups on command.

This allows consonant and vowel differentiation, pitch and volume modulation for vocal play, mimicking intonation, and expressing emotion. From meaninglessly babbling, they acquire articulate speech and versatile vocal control shockingly fast.

Prosody and Emotion

Beyond the mechanics of speech production, the voice can convey a wealth of extra-linguistic information through intentional variations in prosody and emotional expression.

Prosody refers to the rhythm, stress patterns, and intonation that give speech melody beyond the literal definitions of the words. It includes factors like:

• Phrasing and pausing
• Emphasis and accentuation
• Timing and pace
• Pitch modulation
• Loudness variation

Skilled speakers harness prosody not only to hold attention, but to impart meaning through inflection. For example, a rising pitch at the end of a statement turns it into a question.

Emotion is communicated through voice quality variations like harsh, breathy, tense, or shaky tone. Even laughter and crying involve involuntary prosodic patterns and vocalization styles.

Actors train to purposefully modulate pitch, volume, speed, articulation, and voice quality to express emotional states from joy to anger convincingly.

While some prosodic patterns like emphasis are learned, much of vocal emotional expression appears innate. Even children not yet speaking can signal feelings through vocalizations.

However, social norms and language mastery refine this instinctual vocal communication. Ultimately, the voice is about far more than the literal definitions of words alone.

Voiceless vs Voiced Sounds

While vowels are always voiced with vocal fold vibration, consonants can be either voiced or unvoiced. Understanding this distinction is key for both speech development and music production.

Voiced consonants like /z/, /v/, /l/ involve phonation, with the vocal folds adducted and vibrating. Their acoustic signatures show measurable pitch and harmonic overtones.

Unvoiced consonants like /f/, /s/, /p/ are produced without vocal fold vibration. Here, the folds are abducted so that air flows through the open glottis without causing phonation.

Voiceless stops like /p/, /t/, /k/ build up air pressure as articulators seal the vocal tract. When released, there is a burst of turbulence as the pressurized air explodes out, but no pitch.

Fricatives like /f/, /s/ constrict airflow to cause turbulence. But unlike voiced fricatives, the vocal folds do not phonate. Kids learn to master this difference when acquiring language.

Looking at spectrograms reveals the acoustic distinctions: voiced sounds have clear fundamental frequencies while voiceless ones lack measurable pitch and harmonic structure, instead showing diffuse noise.

Understanding voicing differences helps speech therapists assess pronunciation issues. In music production, mix engineers must allow space for consonant transients that lack tonal content compared to sustained voiced vowels and sonorants.

Vocal Registers and Mechanisms

While we all have a natural pitch range, singers learn to expand their limits using different vibrating modes called vocal registers. Moving between registers creates the breaks and transitions characteristic of virtuosic singing.

Registers in Singing Voice

Although every voice is unique, most singers utilize two main registers – chest voice and head/falsetto voice. The acoustic qualities and vocal fold vibration differ between these registers.

Chest voice dominates the lower range, with vocal folds thick and vibrating through their full depth and length. The tone is strong and warm. But as pitch rises, the folds thin out and stretch.

At a certain point, their vibration pattern shifts towards the edges, with the interior vocalis muscle decoupled. This produces head or falsetto voice – thinner, flutelike tone.

Classically trained singers aim to smoothly transition registers through their passaggio or break while many pop/rock singers “belt” to extend chest voice higher.

The break results from laryngeal muscles struggling to stretch the thick folds. With poor technique, the voice cracks or flips into weak head voice prematurely.

Skilled singers minimize the break by developing a strong “mixed voice”. With practice, they coordinate airflow and resonance to maintain chest voice characteristics higher.

Yodeling provides an extreme example of register shifting with rapid alternation between low chest voice and high falsetto notes for effect. Theregister jumps create striking timbral contrasts.

Understanding each singer’s passaggio allows capturing their best take by suggesting keys that keep phrases within a comfortable zone, rather than straining near breaks.

Laryngeal Mechanisms

The vocal anatomy allows several different oscillation modes or laryngeal mechanisms for pitch production. Classical singing technique utilizes three main configurations.

Mechanism 1 uses thick, fully vibrating vocal folds, recruited for low to middle range pitches. This produces modal or chest voice.

In mechanism 2, only the edges vibrate while the interior vocalis muscle layer decouples. This stretches the folds thinner to reach higher pitches in head/falsetto register.

Mechanism 3 further stretches the thin folds under extreme tension for the top of the soprano range, sometimes called whistle or flageolet register. Only very few singers, mostly coloratura sopranos, can access this mechanism.

Most everyday speaking uses mechanism 1. During puberty, the male larynx grows considerably, so adult males remain in M1 for most speech and singing.

Women transition from M1 to M2 around F#4-G4 (370-392 Hz) to access their head register. M2 allows female voices to extend easily an octave higher than the male range.

Singers train to smoothly connect mechanisms through their passaggio or break to avoid sudden register shifts. Understanding registration helps match repertoire to singers’ capabilities and transition points.

Mixed Voice

While vocal registers create obvious breaks in untrained singers, elite vocalists learn to smooth transitions with their “mixed voice”. This blends chest and head qualities to maintain timbre and power through the passaggio.

As less experienced singers ascend in pitch, their vocal folds thin and stretch. Eventally the thyroarytenoid muscle interiorly decouples and chest voice “flips” into weak, breathy head voice.

Mixed voice provides a middle ground, keeping enough vocalis muscle engaged to maintain chest resonance and power. Airflow and fold closure are also optimized.

With practice, singers coordinate breath support and resonance tuning to push the passaggio higher. The goal is minimizing or eliminating register breaks so voice quality remains consistent.

Mixing head and chest voice relies on strengthening the cricothyroid and thyroarytenoid muscles to fine tune fold position. Vocal agility exercises also help coordinate smooth registration shifts.

An expert mixed voice expands range and flexibility. It allows smoother transitions between pitches and dynamics without abrupt color changes between registers.

Recording singers with good mix means capturing smooth takes without worrying about strain near register breaks. Overall timbre and power stay consistent throughout their range.

Vocal Timbre and Resonance

Timbre describes the unique color or tone quality of each voice. While anatomy and physiology form the foundation, vocal timbre stems from a complex interplay of factors.

What Determines Vocal Timbre?

Every voice has a distinctive timbre or tone quality that depends on multiple anatomical factors interacting, including:

• Vocal fold size and shape – Thicker folds and longer membranous lengths produce lower, richer timbre. Shorter, thinner folds give higher, lighter voices.
• Vocal tract dimensions – The length and shape of the pharynx, mouth, and sinus cavities filter sound from the larynx. Longer tracts mean lower resonances and darker tone.
• Articulator flexibility – Loose, elastic articulators allow wider range of movement and precise shaping affecting timbre. Stiff tongues or tense jaws restrict maneuverability.
• Larynx control – Singers with superior control over larynx height and position can dramatically adjust resonance and projection.
• Head and neck size – Larger resonating cavities in the head/neck boost sympathetic vibrations, adding fullness and resonance.
• Tissue density – Dense vocal folds and thicker mucosa produce richer tone. Hydration and vocal health also affect tissue pliability.

Even genetics can’t fully explain a voice – speaking style, accent, and language mastery all shape precise articulation and muscle memory for desired sounds. Vocal training expands timbre control through breath, resonance, and vocal care technique.

Vocal Resonators

The raw sound created by vocal fold vibration is enriched and enhanced by the resonating cavities above them. Vocal timbre depends greatly on how the throat, mouth, and head filter and amplify certain frequencies.

Key resonators include:

• Chest – Expands with inhalation, boosting lower frequencies.
• Trachea – Longer tracheas boost resonance depth.
• Larynx – Larynx height varies resonance; lowered larynx enriches tone.
• Pharynx – Wider shapes increase resonance, narrowed pharynx adds bite and edge.
• Mouth and tongue – Shape modifies formants defining vowels and tone.
• Nasal cavity – Coupled or not to oral cavity, adds distinct resonances.
• Sinuses – Air pockets create sympathetic vibrations, enriching overtones.

Classical male singers use a clustered “singer’s formant” around 3 kHz for projection and presence over orchestras. Enhancing this range makes voices cut through a mix.

Vocal resonances are trainable. Singers exercise greater control over resonance placement and tuning through breath support and articulation.

Stylistic Effects

While classical training aims for purity of tone, many genres utilize exaggerated or even abrasive vocal effects. These stem from alterations to fold closure, resonance, and articulation.

• Twang – Strong, edgy resonances in nasal tract and pharynx.
• Rasp – Harsh irregularities from incomplete fold closure and turbulence.
• Breathiness – Gentle turbulence as air leaks through vocal folds.
• Vocal fry – Very loose folds vibrate irregularly and chaotically.
• Creak – Extremely slow vocal fold vibration creates popping/crackling effect.
• Growl – Added rumbling via larynx lowering or epiglottal trilling.

Spectral slope describes relative strength of harmonics – boosting higher ones creates brighter, sharper tone while attenuating them sounds more mellow and muted.

Many rock/pop singers exploit raspy, gritty qualities that would be undesirable in classical styles. Electronic effects like distortion or octave pedals also transform voice timbre.

Voice Disorders and Care

Elite singers learn to avoid vocal fatigue and damage through proper technique and care. However, improper training, overuse, illness, and even normal aging can lead to disorders affecting vocal fold function.

Common issues like nodules, polyps, and cysts cause hoarseness, loss of range, and vocal fatigue. More serious conditions require medical intervention.

Preventing injury hinges on maintaining vocal health – proper hydration, avoiding irritants, managing reflux, resting swollen folds, and not overextending range.

Voice therapy with a speech pathologist helps identify and reverse harmful habits. Lessons focus on better breath support, resonance placement, and eliminating strain. Customized vocal exercises target strengthening, flexibility, and control.

For chronic issues or growths on the vocal cords, an ENT may prescribe medication, surgery, or injection treatments after a laryngoscopic exam.

Vocal disorders don’t have to end a career. Many professional voice users like actors and teachers regain their abilities through dedication to care, training, and therapy guided by vocal health experts.

Applications in Music Production

Understanding vocal anatomy and technique translates directly into skills for music production. Here are some key applications:

• Coaching singers – Suggest warmups, provide water, and give feedback on breath support, resonance, and reducing strain. Don’t push past fatigue.
• Microphone selection – Choose mics that complement the singer’s timbre. Brighter mics match mellow voices. Proximity effect boosts lows for airy voices.
• Performance variety – Have singers vary register, tone, and emotional expression for options. Layer doubles in head voice and chest voice.
• Pitch correction – Set software appropriately for range and registers to avoid artifacts from incorrect harmonic pattern mapping.
• Equalization – Boost frequencies and formants that give unique identity. Attenuate honky nasal resonances or sibilance.
• Compression – Control dynamics without rapid pumping from plosives. Set attack/release times suited for singer’s articulation.
• Reverb – Add depth and space. Pre-delay complements rhythmic phrasing. Dark plates suit low voices, halls fit sopranos.

Mixing involves highlighting a voice’s strengths while minimizing problems. Knowledge of its acoustic basis lets you make choices that flatter and support the singer.

Final Thoughts

The human voice is an intricately complex instrument. This guide has aimed to demystify its inner workings – from air flowing into the lungs all the way to subtle resonances enriching tone at the lips.

Comprehending the anatomical structures and acoustic phenomena behind speech and singing provides a powerful foundation for mastering both skills. Those new to music may take the voice for granted as an innate ability. However, virtuoso vocalists don’t just rely on raw talent – they learn to consciously control what for most people is primarily involuntary.

Through dedicated training and practice, elite singers acquire tremendous mastery over their vocal anatomy. They develop finessed control over breathing, vocal fold tension, resonance placement, articulation, and more to hit notes with perfect pitch, achieve smooth registrations transitions, craft personalized timbres, and minimize vocal strain.

But one need not become a professional singer to benefit deeply from understanding voice physiology and technique. For any music aficionado or producer, internalizing these concepts will enrich your relationship with the voice immensely. Joining abstract scientific knowledge with extensive firsthand musical experience develops an almost intuitive sense of the voice’s capabilities and beauty.

You will be able to listen with greater nuance and appreciation, pick up subtle techniques used by masters, and better guide vocalists you work with. Whether you dream of Billboard hits or a Grammy nomination, this synthesis of science, technique and art will enhance your musical expression and productions.

We wish you all the best on your own lifelong journey toward vocal excellence! Let this guide illuminate your musical path ahead, that your unique voice may touch listeners profoundly.