Why does your voice change as you get older? - Shaylin A. Schundler

1,726,323 views ・ 2018-08-02

TED-Ed


Please double-click on the English subtitles below to play the video.

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In the mid-16th century,
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Italians were captivated by a type of male singer
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whose incredible range contained notes
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previously thought impossible for adult men.
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However, this gift came at a high price.
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To prevent their voices from breaking,
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these singers had been castrated before puberty,
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halting the hormonal processes that would deepen their voices.
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Known as castrati, their light, angelic voices were renowned throughout Europe,
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until the cruel procedure that created them was outlawed in the 1800s.
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Though stunting vocal growth can produce an extraordinary musical range,
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naturally developing voices are already capable of incredible variety.
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And as we age, our bodies undergo two major changes which explore that range.
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So how exactly does our voice box work, and what causes these shifts in speech?
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The specific sound of a speaking voice is the result of many anatomical variables,
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but it’s mostly determined by the age and health of our vocal cords
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and the size of our larynxes.
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The larynx is a complex system of muscle and cartilage
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that supports and moves the vocal cords,
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or, as they’re more accurately known, the vocal folds.
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Strung between the thyroid and arytenoid cartilages,
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these two muscles form an elastic curtain that opens and shuts across the trachea,
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the tube that carries air through the throat.
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The folds are apart when we’re breathing,
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but when we speak, they slam shut.
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Our lungs push air against the closed folds,
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blowing them open and vibrating the tissue to produce sound.
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Unlike the deliberate focus required for playing an external instrument,
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we effortlessly change notes as we speak.
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By pushing air faster or slower,
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we change the frequency and amplitude of these vibrations,
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which respectively translate to the pitch and volume of our voices.
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Rapid and small vibrations create high-pitched, quiet tones,
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while slow, large vibrations produce deep, bellowing rumbles.
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Finally, by moving the laryngeal muscles between the cartilages,
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we can stretch and contract those folds
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to intuitively play our internal instruments.
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This process is the same from your first words to your last,
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but as you age, your larynx ages too.
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During puberty, the first major shift starts,
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as your voice begins to deepen.
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This happens when your larynx grows in size,
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elongating the vocal folds and opening up more room for them to vibrate.
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These longer folds have slower, larger vibrations,
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which result in a lower baseline pitch.
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This growth is especially dramatic in many males,
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whose high testosterone levels lead first to voice cracks,
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and then to deeper, more booming voices,
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and laryngeal protrusions called Adam’s apples.
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Another vocal development during puberty
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occurs when the homogenous tissue covering the folds
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specializes into three distinct functional layers:
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a central muscle,
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a layer of stiff collagen wrapped in stretchy elastin fibers,
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and an outer layer of mucus membrane.
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These layers add nuance and depth to the voice,
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giving it a distinct timbre that sets it apart from its pre-pubescent tones.
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After puberty, most people’s voices remain more or less the same
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for about 50 years.
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But we all use our voices differently,
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and eventually we experience the symptoms associated with aging larynxes,
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known as presbyphonia.
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First, the collagen in our folds stiffens
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and the surrounding elastin fibers atrophy and decay.
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This decreased flexibility increases the pitch of older voices.
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But for people who have experienced the hormonal effects of menopause,
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the higher pitch is countered and outweighed by swollen vocal folds.
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The folds' increased mass slows their vibrations, resulting in deeper voices.
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All these symptoms are further complicated
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by having fewer healthy laryngeal nerve endings,
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which reduces precise muscle control and causes breathy or rough voices.
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Ultimately, these anatomical changes are just a few of the factors
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that can affect your voice.
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But when kept in good condition,
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your voice box is a finely tuned instrument,
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capable of operatic arias,
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moody monologues,
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and stirring speeches.
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