Introduction to Phonetics: Articulatory, Auditory & Acoustic Branches

A phone is a distinct discrete speech sound, not a letter. Letters are part of the English writing system, while phones represent actual spoken sounds. For example, the English spelling 'th' represents one sound (as in 'thigh') rather than two separate sounds, demonstrating why the English spelling system is insufficient for precise phonetic representation.

When writing, we use letters, but when speaking, we use phonemes. Letters are visual symbols that represent sounds, but the actual sounds produced when speaking are phonemes. This distinction is fundamental to understanding how language works at both written and spoken levels.

This comprehensive section covers the fundamental distinction between phonology (study of mental, abstract sounds in the mind) and phonetics (study of articulated, material sounds produced during speech). It introduces key concepts: phonemes (smallest mental units with distinctive value that change word meaning) versus phones (actual produced sounds); the closed inventory of 24 Spanish phonemes (5 vowels, 19 consonants) versus the open inventory of infinite phones; and graphemes as written representations. The section explores Spanish orthography with its 27 letters and 5 digraphs, demonstrating how letters don't always correspond directly to phonemes (b/v, y/i, x/s/k). Special cases include silent h, variable x, and the relationship between letters and sounds in words like 'sexo' (4 letters, 5 sounds).

Phonemes are the sound units that compose speech, represented by diagonal bars to separate each sound. Letters are the graphic signs that enable writing, representing the sounds that are pronounced. Together, they form the alphabet. The key distinction is that phonemes are oral sounds while letters are their written representations. Understanding this difference is essential for analyzing words and their structure.

This lesson covers fundamental concepts in language and linguistics. Speech is the oral form of language and is regarded as the original or primary form, while writing is the graphic form and is only an imperfect imitation of speech. Many languages have oral forms but not written forms. Key differences include: speech is oral manifestation while writing is graphic representation; speech is primary while writing is secondary; speech is inevitable to learn a language while writing is optional; all natural languages have spoken form but only standard languages have written form; speech is temporary while writing is permanent; speech is audible while writing is visible; speech uses sounds while writing uses letters. There are two writing systems: orthographic writing uses letters of the alphabet and is based on spelling (26 symbols in English), while phonetic writing uses sound symbols (44 symbols in English). Orthographic writing is also known as graphic writing or transcription writing and is easier to learn compared to phonetic writing.

The larynx (voice box) contains vocal folds examined via endoscopy using scopes inserted through the mouth or nose. The arytenoid cartilages bring vocal folds together for phonation. Male adult voices have larger larynges than females, explaining the Adam's apple prominence and voice type classifications (soprano, alto, tenor, bass). The voice operates as an integrated system with four components: the actuator (breath as power source), vibrator (muscular vocal folds), resonator (vocal tract including larynx, pharynx, and oral cavity), and articulator (tongue and lips shaping sound). Understanding this anatomical foundation is essential for comprehending how the human voice produces sound.

The larynx is the upper part of the trachea (windpipe) through which air passes to reach the lungs. Inside the larynx are the vocal cords (वाक तंतु), which open and close and vibrate to produce sound. This is why the larynx is also called the voice box. The vocal cords vibrate to produce sound, and the size of the larynx differs between males and females - females have a smaller larynx while males have a slightly larger one.

The vocal apparatus includes the nasal passages, sinuses, pharynx, larynx, trachea, and lungs. The larynx contains the vocal cords where voice is produced. The pharynx is prone to inflammation. The lungs are essential for respiration and immune function, with the diaphragm controlling breathing. The vocal apparatus is divided into three parts: the oral cavity (including teeth, palate, and tongue), the pharyngeal cavity, and the laryngeal cavity. The oral cavity is where articulation of vowels and consonants occurs.

Human voice production involves four main systems working in sequence: (1) Abdominal muscles (naabhi pradesh) compress air upward, (2) Chest (uraha) and diaphragm generate pressure, (3) Larynx (kandha) with vocal cords produces fundamental sound, (4) Oral and nasal cavities shape sounds into words. The oral cavity contains six places of articulation: throat (kandha), palate (talva), roof of mouth (murdha), teeth (danta), lips (oshtha), and nose (nasika). Each place produces specific types of sounds. The complete process begins with abdominal muscles pushing air to the chest, then through the respiratory system, through the larynx where vocal cords vibrate, and finally into the oral/nasal cavities where it is shaped into specific sounds before being expelled.

The speech apparatus is located in three main body regions: (1) The chest contains the lungs (Ri'atayn) which serve as the air source, (2) The neck contains the larynx (Hanjara), and (3) The head contains three interconnected cavities: the pharyngeal cavity (Tajawif al-Halqi), the oral cavity (Tajawif al-Famawi), and the nasal cavity (Tajawif al-Anfi). The lungs are composed of sponge-like tissue that expands and contracts to move air. The larynx is the first site of airway obstruction and consists of the thyroid cartilage (superior) and cricoid cartilage (inferior).

Frequency is the number of vibrations per second (measured in Hz), determining the pitch of sound—higher frequency produces higher pitch, while lower frequency produces lower pitch. Amplitude is the maximum displacement from the equilibrium point in a wave, determining the loudness of sound—larger amplitude produces louder sound, while smaller amplitude produces softer sound. Sound waves are mechanical longitudinal waves that require a medium to propagate, with frequency categorized into infrasonic (below human hearing), audible (within human hearing range), and ultrasonic (above human hearing range).

Sound waves have three key properties: frequency (number of cycles per second, measured in Hertz), amplitude (maximum displacement of particles), and wavelength (distance between corresponding points on consecutive waves). Frequency determines pitch—higher frequency means higher pitch. Amplitude determines loudness—greater amplitude means louder sound. All sound waves travel at the same speed in a given medium. The relationship between frequency, wavelength, and speed is: speed = frequency × wavelength.

Sound is produced by vibrations of objects and requires a medium (air, liquid, or solid) to propagate. Medium particles vibrate and transfer energy from the source to the listener's ears. Amplitude is the maximum displacement of a medium particle from its equilibrium position, measured from equilibrium to the extreme point. When medium particles have more kinetic energy, they displace more, resulting in greater amplitude. Frequency is the number of complete waves or cycles passing a point in one second, measured in Hertz (Hz). One complete wave cycle is called one oscillation. Frequency is inversely proportional to the time period (the time for one complete wave cycle), with the relationship: Frequency = 1/Time Period.

Sound waves are longitudinal waves where the medium (air molecules) moves back and forth in the same direction as the wave propagation; frequency determines pitch (measured in hertz as cycles per second), amplitude determines loudness (related to voltage and energy), and the speed of sound in air is approximately 343 meters per second, determined by the medium's properties.

Sound waves possess measurable properties that determine their characteristics. Amplitude measures the magnitude of pressure changes and corresponds to loudness—greater amplitude means louder sounds. Frequency measures how many cycles pass through a point per second and determines pitch, with higher frequencies producing higher-pitched sounds. Humans can typically hear frequencies between 20 Hz and 20,000 Hz, with sounds outside this range being ultrasound or infrasound that cannot be perceived by human ears.