What Determines What Your Voice Sounds Like?

ThinkStock
ThinkStock

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.

HE SAYS/SHE SAYS

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. 

Why Are Sloths So Slow?

Sloths have little problem holding still for nature photographers.
Sloths have little problem holding still for nature photographers.
Geoview/iStock via Getty Images

When it comes to physical activity, few animals have as maligned a reputation as the sloth. The six sloth species, which call Brazil and Panama home, move with no urgency, having seemingly adapted to an existence that allows for a life lived in slow motion. But what makes sloths so sedate? And what horrible, poop-related price must they pay in order to maintain life in the slow lane?

According to HowStuffWorks, the sloth’s limited movements are primarily the result of their diet. Residing mainly in the canopy vines of Central and South American forests, sloths dine out on leaves, fruits, and buds. With virtually no fat or protein, sloths conserve energy by taking a leisurely approach to life. On average, a sloth will climb or travel roughly 125 feet per day. On land, it takes them roughly one minute to move just one foot.

A sloth’s digestive system matches their locomotion. After munching leaves using their lips—they have no incisors—it can take up to a month for their meals to be fully digested. And a sloth's metabolic rate is 40 to 45 percent slower than most mammals' to help compensate for their low caloric intake. With so little fuel to burn, a sloth makes the most of it.

Deliberate movement shouldn’t be confused for weakness, however. Sloths can hang from branches for hours, showing off some impressive stamina. And because they spend most of their time high up in trees, they have no need for rapid movement to evade predators.

There is, however, one major downside to the sloth's leisurely lifestyle. Owing to their meager diet, they typically only have to poop once per week. Like going in a public bathroom, this can be a stressful event, as it means going to the ground and risking detection by predators—which puts their lives on the line. Worse, that slow bowel motility means they’re trying to push out nearly one-third of their body weight in feces at a time. It's something to consider the next time you feel envious of their chill lifestyle.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

Are Any of the Scientific Instruments Left on the Moon By the Apollo Astronauts Still Functional?

Apollo 11 astronaut Neil Armstrong left the first footprint on the Moon on July 20, 1969.
Apollo 11 astronaut Neil Armstrong left the first footprint on the Moon on July 20, 1969.
Heritage Space/Heritage Images/Getty Images

C Stuart Hardwick:

The retroreflectors left as part of the Apollo Lunar Ranging Experiment are still fully functional, though their reflective efficiency has diminished over the years.

This deterioration is actually now delivering valuable data. The deterioration has multiple causes including micrometeorite impacts and dust deposition on the reflector surface, and chemical degradation of the mirror surface on the underside—among other things.

As technology has advanced, ground station sensitivity has been repeatedly upgraded faster than the reflectors have deteriorated. As a result, measurements have gotten better, not worse, and measurements of the degradation itself have, among other things, lent support to the idea that static electric charge gives the moon an ephemeral periodic near-surface pseudo-atmosphere of electrically levitating dust.

No other Apollo experiments on the moon remain functional. All the missions except the first included experiment packages powered by radiothermoelectric generators (RTGs), which operated until they were ordered to shut down on September 30, 1977. This was done to save money, but also because by then the RTGs could no longer power the transmitters or any instruments, and the control room used to maintain contact was needed for other purposes.

Because of fears that some problem might force Apollo 11 to abort back to orbit soon after landing, Apollo 11 deployed a simplified experiment package including a solar-powered seismometer which failed after 21 days.

This post originally appeared on Quora. Click here to view.

SECTIONS

arrow
LIVE SMARTER