I am studying to take the TOEFL exam, which I need to pass if I have any hope of a job promotion. The problem I encountered is the following.

The TOEFL textbook gives me the following example. (It is talking about the acoustic function of human body).

Whenever you speak, your vocal cords vibrate.

The slower the vibration, the lower the pitch.

To raise the pitch of vibrating string, tighten it.

My research:

After googling and looking up the different terms in a dictionary, I came to think that the expression in bold might refer to the fiber of the human beings' vocal cord.


At birth, vocal cords are composed of a uniform, gel-like material. As the vocal cords mature, fibers develop within the gel, eventually forming a multilayered, laminated string. Imagine a set of guitar strings glued close together with gelatin.

(I don't understand the part "Imagine a set of guitar strings glued close together with gelatin")

A simple string

Despite the complexities of the vocal cord structure, Titze says he was surprised at how well the model of a simple vibrating string explained the cord's range. "Most people would laugh at using a simple vibrating string model for something as complicated as a 3-D, nonhomogeneous tissue structure," he says. "But the string model does an incredibly good job of explaining this range of frequencies."

  • So my final assumption is that the "vibrating strings" would mean some sort of fibers comprising of a human being's vocal cord.

  • Would my assumption/understanding be correct?

Thank you for your any support sincerely.

  • 1
    Yes, your textbook example looks like something that would be too technical for a TOEFL exam, where they test your understanding of English (not physics or physiology).
    – GEdgar
    Commented Jul 21, 2018 at 18:31
  • My apology for not looking up other site. Next time, I will ask at Physics site. Kindly forgive me. ( Though the answerer, Ibf, seems to be elaborating furthermore, for this question only, let me wait for a while. Again I apologize that I didn't search for the better place to ask. )
    – user193343
    Commented Jul 21, 2018 at 18:33
  • Look up "metaphor".
    – Hot Licks
    Commented Jul 21, 2018 at 19:03
  • 1
    Then you will have a lot of trouble with English, because it's full of metaphors.
    – Hot Licks
    Commented Jul 21, 2018 at 20:24
  • 3
    The use of ’string’ here doesn’t mean rhe vocal chords. It means string- the stuff you tie things with or the string of a musical instrument- both work here. It’s saying before looking at the vocal chords let’s just look at how simple string behaves. Once we understand that we can then relate that to how the human vocal chords work.
    – Jim
    Commented Jul 22, 2018 at 3:54

2 Answers 2


Vocal Folds in Phonation physics

The process of converting the air pressure from the lungs into audible vibrations is called phonation. When the air passes through the elastic vocal folds and causes them to vibrate, the type of phonation is called voicing. The vocal folds give the singer a wide range of control over the pitch of the sound produced. While "vocal folds" is more descriptive than "vocal cords", there is some similarity to a vibrating string [a violin] in that the pitch produced depends upon the length, mass and tension of the vocal folds.

Your question:

So is my final assumption is that the "vibrating strings" would mean some sort of fibers comprising of human being's vocal cord?

Yes. In actuality they are fibers [lay: strings] made of mucous membranes, derived from epithelium. ENT Clinics of N.A. and Elastic system fibers the metaphor ( or analogy if you will) is in comparing strings of a musical instrument, made of many fibers, to the elastic-system fibers in human vocal cords.

vocal folds

  • Ah, I am sorry I didn't know there is Physics site. Please forgive me.
    – user193343
    Commented Jul 21, 2018 at 18:27
  • Thank you so much for your research and I sincerely apologize for not having tried to find "better place" to ask. But I appreciate your answer. Thank you so much.
    – user193343
    Commented Jul 21, 2018 at 18:35

The vibrating string in the TOEFL example is the vocal cord, as others have pointed out.

However, you should realize that the vibrating string is an abstraction that most native speakers of English will know from childhood experience at home and in the school system.

Stringed instruments are everywhere in the English-speaking world. A school with a music program will often include some kind of stringed instrument, e.g. the 4-string ukulele in elementary school. Acoustic and electric guitars are heard everywhere. Every child knows what they are, and many children play them, or at least know someone who does.

As a result, the relationship between pitch and string tension is usually encountered at an early age, and the vibrating string comes back as an example in middle school science and later in high school science. It's something that every student can relate to.

One can argue that a person writing the Test of English as a Foreign Language should not be expected to know things that are learned in childhood by native speakers. However, the tests are devised by ordinary people with ordinary cultural experiences. It's hard to get around that.

  • Thank you very much for your informative answer. Pardon me for one thing. I am the test taker and not the test maker. But anyway, please allow me to accept Ibf's answer as the best since he answered correctly. I appreciate you enhanced further about this question.
    – user193343
    Commented Jul 23, 2018 at 2:54
  • 1
    @KentaroTomono I think you made the right call. I thought lbf’s answer was very good. I originally just planned to make a comment but I ran out of space.
    – user205876
    Commented Jul 23, 2018 at 4:05

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