Question

What is the role of the vocal cords in speech?

• A. Produce airflow
• B. Create sound vibrations
• C. Modify vowel quality
• D. Control nasal airflow

Answer 1

Answer:

B. Create sound vibrations

The Role of Vocal Cords in Speech Production

• Anatomy and Location: The vocal cords, also known as vocal folds, are two bands of smooth muscle tissue located within the larynx, commonly referred to as the voice box. The larynx sits at the top of the trachea (windpipe).
• Mechanism of Phonation: Their primary role is to create sound vibrations through a process called phonation or vocalization. This happens when air expelled from the lungs passes through the glottis, which is the opening or space between the vocal cords.
• Vibratory Action: As air flows through the glottis, it causes the vocal cords to rapidly open and close, setting them into vibration. This rapid vibration generates pressure waves in the air, which are perceived as sound. The faster the vibration, the higher the pitch of the sound.
• Control of Pitch and Loudness:
  • Pitch is primarily determined by the tension and length of the vocal cords. Tighter and longer cords vibrate at a higher frequency, producing a higher pitch. Looser and shorter cords vibrate slower, resulting in a lower pitch.
  • Loudness (or intensity) is influenced by the force of the air expelled from the lungs and the amplitude of the vocal cord vibrations. More forceful airflow leads to wider vibrations and a louder sound.
• Resonance and Articulation: The initial sound vibrations produced by the vocal cords are then modified and amplified by the resonating chambers, which include the pharynx (throat), oral cavity (mouth), and nasal cavity. These sounds are further shaped into distinct speech sounds (phonemes) by the articulators, such as the tongue, lips, teeth, and soft palate.
• Phonology Connection: In the field of phonology, which studies the sound system of languages, the vocal cords' function is crucial for distinguishing between voiced sounds (e.g., /b/, /d/, /g/, /v/, /z/, and all vowels), where the vocal cords vibrate, and voiceless sounds (e.g., /p/, /t/, /k/, /f/, /s/), where they do not vibrate.
• Key Facts for Competitive Exams:
  • The average length of male vocal cords is approximately 17-25 mm, while female vocal cords are typically shorter, about 12.5-17.5 mm. This anatomical difference contributes to the general lower pitch of male voices.
  • The typical vibration frequency for adult males is around 100-150 Hz (vibrations per second), whereas for adult females, it ranges from 180-250 Hz.
  • The scientific study of sound, including its production, transmission, and reception, is known as acoustics.
  • Common disorders affecting vocal cords include laryngitis (inflammation), vocal nodules (singer's nodes), and polyps, all of which can significantly impair voice quality.
  • The primary nerve responsible for controlling the movement of the vocal cords is the recurrent laryngeal nerve, a critical branch of the vagus nerve (Cranial Nerve X).