As a marker of singularity, our voices are as effective as our fingerprints. Though people may share a similar pitch or certain vocal characteristics, under close examination, no two voices are alike. Height, weight, hormones, provenance, allergies, structural anomalies, emotions, and environmental factors all play a role in determining how your voice ultimately emerges, which means not only is your voice yours alone, but that you’ll have a few variations on that voice throughout your life.
The first and most obvious vocal determinate is your sex. Anatomically, males have larger vocal folds (aka vocal cords) than females, so, even before hormones surge during adolescence, boys typically have deeper voices than girls. These folds are stretched horizontally across the larynx (the voice box) and, when air is brought up from the lungs to speak, they vibrate. The length, size, and tension of the folds determine what’s known as the fundamental frequency of the resulting sound, which averages about 125 Hz in men, 210 Hz in women, and 300-plus Hz in children. The higher the Hz, or frequency of the sound wave, the higher the pitch. High frequency sounds reach our ears faster, partially explaining why kids’ voices can be so grating.
When we hit puberty, hormones invariably cause the voice to change. During this time the vocal folds lengthen and thicken, causing them to resonate at a lower frequency, which produces a deeper pitch (think of the strings on a guitar). In males, the production of testosterone ramps up, and the larynx increases in size. Men that produce higher levels of testosterone during puberty will usually develop lower voices as they grow into adulthood. Girl’s vocal folds will also grow a bit (about 3 mm compared to 10 mm in boys), but, since they’re not churning out testosterone, their voices remain comparatively high.
Genetics also play a role in how our voices mature. Although how a child’s voice develops owes something to mimicry of their parents, people from the same family will often sound alike because laryngeal anatomy is dictated by your ancestral DNA just like every other physical trait. It’s the slight variations around this anatomy that make our voices distinct.
CHANGING YOUR TUNE
The voice you enter adulthood with is, by and large, the voice you’re stuck with for most of your life. That said, there are several factors that can influence vocal changes, many of which are fleeting, some of which are not. A temporary voice change happens when you catch a cold. Here, the cold virus makes the vocal cords swell, causing them to rub together, which lends a rasp to our speech (the irritation is further aggravated by an urge to clear your throat, which makes the swelling worse).
Our emotional state also affects how we speak. When we’re excited, nervous, or frightened, the muscles buttressing the larynx contract involuntarily, and tension in the vocal cords will increase to produce that high, unsteady pitch we associate with alarm. Though the voice will return to normal once the stimulus passes, people who are generally high-strung will often adopt some variation of this alarmed voice as their natural cadence.
One of the most frequently applied vocal designations is describing someone as “nasally.” A voice that seems birthed as much in your nose as in your throat can be caused by a number of things, which are separated into two categories. Hyponasal speech, the more common of the two, occurs when there’s a lack of airflow through the nose while speaking. Nasal congestion is the primary culprit, as anyone with allergies or chronic sinusitis can attest to, but hyponasality can also stem from a deviated septum or certain adenoidal maladies. Hypernasal speech, on the other hand, results from an influx of air through the nose while speaking, and is especially noticeable when saying words that begin with a consonant. Hypernasality can be caused by a cleft palate or other velopharyngeal insufficiencies, and speech can be majorly impaired in these cases.
Some of the common environmental and lifestyle factors that contribute to what your voice sounds like include pollution, an overly dry climate, smoking, drinking alcohol, or shouting/screaming too much. The vocal cords and larynx are like any other muscle in that they can be overused and strained, so, like most things, moderation is key when it comes to taking care of your voice.
The inevitability of aging will lead to a final, permanent voice change for most of us. After a lifetime of speaking, the vocal cords and surrounding tissue lose strength and elasticity, and our mucous membranes become thinner and drier. Known medically as presbyphonia, elderly voice change manifests itself through reduced volume and endurance, noticeable shakiness, and difficulty being heard. Ironically, at this age men’s voices will increase in pitch, while women’s will lower, in a kind of reverse adolescence.
