#acoustics

• Aerophone — As a noun, it represents any musical instrument (such as the flute, trumpet, or organ) in which sound is produced exclusively by the vibration of an insufflated mass of air, without the aid of strings or tensioned membranes. The classification belongs to the Hornbostel-Sachs system. As an adjective, it describes a system or device capable of transmitting sound via air currents.
• Aphonic — Relating to aphonia; characterized by the total or partial absence of voice or articulated sound. In medicine, it describes a person who can only whisper due to physical or psychological laryngeal conditions. In acoustics, it applies to voiceless sounds produced without vocal cord vibration.
• To devoice — To deprive of sound, echo, or sonorous properties; to transform a voiced sound into a voiceless one by stopping the vibration of the vocal cords. In modern acoustic engineering, the term is used very rarely to describe the complete attenuation of sound emissions.
• Devoicing — The act of devoicing or deadening sound; the process of transforming a voiced sound into a voiceless one by stopping vocal cord vibration during articulation. In audio engineering, it describes the extreme attenuation of sound waves or the mitigation of resonance within an acoustic chamber.
• Aliquote sounds — An acoustic and musical technical term designating higher harmonic sounds (flageolets) produced naturally by the secondary vibration of a string or through overblowing in wind instruments; it also refers to sympathetic strings or special organ registers designed to reproduce or reinforce these upper harmonics.
• Alphorn — A traditional, large-sized wind musical instrument (several meters long), structurally crafted from hollowed softwood wrapped in birch bark, equipped with a flared curved bell at the lower end and a wooden mouthpiece. This alpine horn, specific to the mountain regions of Switzerland and Austria, produces powerful, warm natural harmonic sounds, historically utilized by shepherds for long-distance communication between ridges and for signaling.
• Amplitude magnitude — A shortened form or acronym used in digital technology, audio engineering, and signal processing to designate the absolute magnitude of an amplitude; in computer science, it may represent a technical variable identifier or a specific compressed file extension.
• Amplification — The act of amplifying and its result; a physical, electronic, or mathematical process through which the intensity, power, amplitude of a signal or the value of a fraction's terms is increased. In electronics, it represents the boosting of an input quantity using a specialized device that draws from an external energy source, ensuring optimal data transmission and processing.
• Anacoustics — A specialized branch or area of study within modern physics and sound engineering dealing with the analysis of the absolute absence of sound or the propagation of elastic waves in extremely low-density media (such as vacuums or upper atmospheric layers), where the transmission of acoustic waves becomes structurally impossible due to the lack of a fluid molecular medium.
• Reed — A thin, elastic tongue made of reed, plastic, or metal, used to produce sound through vibration under air pressure in certain wind instruments (such as the clarinet, saxophone, or oboe). It represents the essential acoustic element for controlling timbre, dynamics, and expressive flexibility in generating sound waves specific to woodwinds.
• Reed — A rare spelling variant or unadapted direct loanword for the term anceu; a thin, elastic reed blade made of cane or plastic fixed to the mouthpiece of certain wind instruments to produce sounds through vibration under air pressure.
• Anemochord — A rare historical or musical archaic term used to designate an Aeolian harp or a stringed musical instrument structurally designed to produce harmonic sounds exclusively under the direct action of wind or air currents vibrating the stretched strings.
• Animal archive — A systematic collection, archive, or specialized library dedicated to the storage and preservation of biological materials, audio-video recordings, or documents relating to the animal kingdom. In modern research and bioacoustics, the term describes a digital or physical database storing tissue samples, genetic sequences, or sound samples (vocalizations) emitted by various animal species, used for taxonomic, ecological, or educational purposes.
• Antiphase — A state or relationship between two periodic quantities (waves, oscillations, signals) of the same frequency, characterized by a phase difference of exactly 180 degrees (or π radians); phase opposition. In acoustic and electronics engineering, bringing waves into antiphase is the core principle used for active noise cancellation.
• Antiphase — Being in phase opposition (shifted by exactly 180 degrees) relative to another oscillatory signal, electromagnetic wave, or sound wave of the same frequency. In modern audio technology, antiphase signals are utilized for active noise cancellation.
• Antiphon — A material, device, or chemical compound used for soundproofing, noise reduction, or acoustical vibration damping (especially in automotive or construction industries); in Christian liturgical music (theology), it represents a hymn, verse, or psalm sung alternatively by two separate choirs.
• Soundproofed — Covered with a layer of soundproofing compound or acoustic insulating materials to prevent the propagation of noise and vibrations; as a neuter noun, it designates the completed work, result, or process of insonorizing a surface or vehicle.
• Antiphonal — Insulating against noise or damping sound vibrations; pertaining to soundproofing or acoustic reduction. In liturgical or religious music (theology), the term describes a hymnal structure or a mode of vocal performance based on the symmetrical alternation and dialogue between two separate choirs.
• Antinodal — Pertaining to or relating to an antinode (venter); located in the region of maximum amplitude of a standing wave, where the constructive interference of the component waves causes the maximum displacement, oscillation, or variation of a physical parameter (pressure, velocity, electric field).
• Noise-canceling — Isolating, mitigating, absorbing, or canceling noise pollution, parasitic sounds, or unwanted acoustic waves. It applies to insulating materials (sound-absorbing panels, rock wool), highway barriers, engine protective casings, or active electronic technologies (such as ANC headphones) structurally designed to ensure optimal sonic comfort in industrial, urban, or residential environments.