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Human voice

life science Maturity 7-9 Next article →

The human voice is a complex biological system used for communication and expression. It includes many sounds like talking, singing, laughing, and crying. Beyond just words, the voice can reveal a person's age and sex. It also serves as a powerful tool for expressing emotions like anger, fear, or happiness. Because of unique body shapes, every person's voice is entirely different.

Human voice spectrogram
Human voice spectrogram

Generating the human voice requires three main components working in sequence. First, the lungs act as a pump to create necessary airflow and air pressure. This air travels up to the larynx, which is also known as the voice box. Inside the larynx, the vocal folds vibrate to turn that airflow into audible pulses. These pulses serve as the primary laryngeal sound source. Finally, the articulators shape the sound. These include the tongue, palate, cheeks, and lips. They filter the sound coming from the larynx to create specific speech.

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The vocal folds themselves have a specific anatomy. They are pearly white, flat, triangular bands. They are attached at the back to the arytenoids cartilages. At the front, they attach to the thyroid cartilage. These folds have a three-layer construction. This includes an epithelium, a vocal ligament, and the vocalis muscle. The muscle can shorten or bulge the folds to change their shape. Above these folds lies the vestibular fold, often called the false vocal cord.

Physical differences in the vocal folds lead to different voice pitches. In adult men, the vocal folds typically measure between 17 mm and 25 mm in length. In adult women, they generally measure between 12.5 mm and 17.5 mm. Because men usually have larger folds and larger vocal tracts, their voices tend to be lower. This physical difference allows for various singing voice types. Men are categorized into types like bass, baritone, and tenor. Women are categorized into types such as contralto, mezzo-soprano, and soprano.

Speech is also shaped by how the vocal folds move together or apart. This is called vocal fold adduction when they come together. It is called abduction when they separate. The muscles controlling this action are among the fastest in the human body. This speed is vital for life-preserving functions, such as keeping food from entering the lungs. When the folds separate strongly during speech, the sound is called voiceless. If they move together in a specific way, it can create a glottal stop. Even children learn these complex movements by listening to adults before they are two years old.

Singers use a process called vocal resonation to enhance their sound. This happens when the sound passes through various air-filled cavities in the body. These resonators include the chest, the larynx, the pharynx, the oral cavity, and the nasal cavity. By using these spaces, singers can increase the intensity and timbre of their voice. Many singers use the "singer's formant" to help their voices carry. This is a specific resonance that helps the voice stay audible above musical instruments.

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The human voice is also linked to the foundations of music. A 2021 study in the Journal of Neuroscience suggested a connection to the twelve-tone musical scale. Researchers found that peaks in acoustic energy in speech mirrored the distances between musical notes. This suggests that the scale may have roots in the evolution of the human voice. Furthermore, different vocal registers exist based on how the folds vibrate. Speech pathologists identify four specific registers: vocal fry, modal, falsetto, and whistle. These different patterns allow for a massive range of human sound.

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