What Are Vocal Cords?

“Dad?” my son asks. “Why does Darth Vader sound funny?”

We’re sitting on the couch when he asks the question. I’m reading, and he’s playing with his Legos, and the question doesn’t come from as far out of left field as it might seem. The majority of his Legos are Star Wars themed, after all. “Because the people who made the movie wanted him to sound scary,” I say.

“No,” he huffs. “I mean, in the movie!”

“Oh,” I say. “Well, his vocal cords got hurt when he fought Obi Wan.”

“Vocal chords?” he asks, sounding baffled. “What are vocal chords?”

What Indeed?

I don’t know, to be honest. Oh, sure, I know they’re the things in your throat that vibrate when you talk, and that they’re the things that actually let you speak. But I have no idea beyond that. The name always made me imagine a set of fleshy guitar strings stretched across my throat – when I thought about it at all – but I’m fairly confident that this isn’t correct. So, let’s look into the answer. Literally.

Vocal Cords

Those are vocal cords – also known as vocal folds – in action. Medscape describes them as “mucous membrane infoldings that stretch horizontally across the middle laryngeal cavity. They are attached anteriorly at the angle on the interior surface of the thyroid cartilage and project posteriorly to the arytenoid cartilages on either side.” They’re found within the larynx, at the top of the trachea, and open when inhaling and close when swallowing. They also close to help vibrate and modulate air expelled from the lungs to enable us to produce sounds (like, for instance, speech).

illu_larynx

Technically, there are two sets of vocal cords. The “true vocal cords” (or vocal folds) and the “false vocal cords” (or vestibular folds). These vestibular folds primarily serve to protect the more delicate vocal folds, but may also be “used in the production of deep tones and screaming or throat singing”. So, if you happen to enjoy black metal or Tuvan or Mongolian throat singing, you have heard and appreciated the false vocal cords.

On average, adults have larger vocal cords than children and men have larger vocal cords than women. This is why, again on average, adults have deeper voices than children and men have deeper voices than women. Larger vocal cords vibreate more slowly and with a longer frequency, creating lower sounds. Women are also more likely to have vocal folds that appear to be a pearly white, while men are more likely to have pinkish vocal cords.

Human are not born with fully developed vocal folds. Infants lack a vocal ligament, which allows the muscles of the larynx to easily control the vocal folds. “The vocal ligament begins to appear at about 4 years of age. The formation of the 3 defined lamina propria layers occurs between the ages of 6 and 12 and are fully mature at the end of adolescence.”

Care to tie this back to Star Wars?

Of course I would, because that’s what spawned this question. Clearly, the vocal cords can be damaged – acid reflux and smoking can thicken them, and significant use can stiffen them. Stiff vocal cords don’t vibrate as well, reducing vocal range and making speech difficult. Surgeons can repair this stiffness by replacing the vocal cords with synthetic materials. Specifically, a variation of polyethylene glycol called PEG30, which mimics the flexibility of human vocal cords and moves in a very similar manner to the natural tissues that compose them. So, instead of having a raspy mechanical voice, Darth Vader could have been given an amazing singing voice.

Not that the Dark Lord of the Sith doesn’t rock out anyway.

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