Acoustics is a branch of physics that deals with the study of mechanical waves in gases, liquids, and solids including topics such as vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics technology may be called an acoustical engineer. The application of acoustics is present in almost all aspects of modern society with the most obvious being the audio and noise control industries.
Infrared spectroscopy is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection. It is used to study and identify chemical substances or functional groups in solid, liquid, or gaseous forms. It can be used to characterize new materials or identify and verify known and unknown samples. The method or technique of infrared spectroscopy is conducted with an instrument called an infrared spectrometer which produces an infrared spectrum. An IR spectrum can be visualized in a graph of infrared light absorbance on the vertical axis vs. frequency, wavenumber or wavelength on the horizontal axis. Typical units of wavenumber used in IR spectra are reciprocal centimeters, with the symbol cm−1. Units of IR wavelength are commonly given in micrometers, symbol μm, which are related to the wavenumber in a reciprocal way. A common laboratory instrument that uses this technique is a Fourier transform infrared (FTIR) spectrometer. Two-dimensional IR is also possible as discussed below.
Longitudinal waves are waves in which the vibration of the medium is parallel to the direction the wave travels and displacement of the medium is in the same direction of the wave propagation. Mechanical longitudinal waves are also called compressional or compression waves, because they produce compression and rarefaction when travelling through a medium, and pressure waves, because they produce increases and decreases in pressure. A wave along the length of a stretched Slinky toy, where the distance between coils increases and decreases, is a good visualization. Real-world examples include sound waves and seismic P-waves.
Infrasound, sometimes referred to as low frequency sound, describes sound waves with a frequency below the lower limit of human audibility. Hearing becomes gradually less sensitive as frequency decreases, so for humans to perceive infrasound, the sound pressure must be sufficiently high. Although the ear is the primary organ for sensing low sound, at higher intensities it is possible to feel infrasound vibrations in various parts of the body.
Ernst Florens Friedrich Chladni was a German physicist and musician. His most important work, for which he is sometimes labeled as the father of acoustics, included research on vibrating plates and the calculation of the speed of sound for different gases. He also undertook pioneering work in the study of meteorites and is regarded by some as the father of meteoritics.
Huntsman spiders, members of the family Sparassidae, are known by this name because of their speed and mode of hunting. They are also called giant crab spiders because of their size and appearance. Larger species sometimes are referred to as wood spiders, because of their preference for woody places. In southern Africa the genus Palystes are known as rain spiders or lizard-eating spiders. Commonly, they are confused with baboon spiders from the Mygalomorphae infraorder, which are not closely related.
An audio frequency or audible frequency (AF) is a periodic vibration whose frequency is audible to the average human. The SI unit of frequency is the hertz (Hz). It is the property of sound that most determines pitch.
Bioacoustics is a cross-disciplinary science that combines biology and acoustics. Usually it refers to the investigation of sound production, dispersion and reception in animals. This involves neurophysiological and anatomical basis of sound production and detection, and relation of acoustic signals to the medium they disperse through. The findings provide clues about the evolution of acoustic mechanisms, and from that, the evolution of animals that employ them.
The auditory system is the sensory system for the sense of hearing. It includes both the sensory organs and the auditory parts of the sensory system.
Whales use a variety of sounds for communication and sensation. The mechanisms used to produce sound vary from one family of cetaceans to another. Marine mammals, including whales, dolphins, and porpoises, are much more dependent on sound than land mammals due to the limited effectiveness of other senses in water. Sight is less effective for marine mammals because of the way particulates in the ocean scatter light. Smell is also limited, as molecules diffuse more slowly in water than in air, which makes smelling less effective. However, the speed of sound is roughly four times greater in water than in the atmosphere at sea level. As sea mammals are so dependent on hearing to communicate and feed, environmentalists and cetologists are concerned that they are being harmed by the increased ambient noise in the world's oceans caused by ships, sonar and marine seismic surveys.
"Good Vibrations" is a song by the American rock band the Beach Boys that was composed by Brian Wilson with lyrics by Mike Love. It was released as a single on October 10, 1966 and was an immediate critical and commercial hit, topping record charts in several countries including the United States and the United Kingdom. Characterized by its complex soundscapes, episodic structure and subversions of pop music formula, it was at the time the most expensive single ever recorded. "Good Vibrations" later became widely acclaimed as one of the finest and most important works of the rock era.
The Hum is a name often given to widespread reports of a persistent and invasive low-frequency humming, rumbling, or droning noise audible to many but not all people. Hums have been reported all over the world, including the United States, the United Kingdom, Australia and Canada. They are sometimes named according to the locality where the problem has been particularly publicized, such as the "Taos Hum" in New Mexico and the "Windsor Hum" in Ontario.
A skyquake is a phenomenon where a loud banging sound is reported to originate from the sky. The sound may cause noticeable vibration in the ceiling or across a particular room. Those who experience skyquakes typically do not have a clear explanation for what caused them and they are perceived as mysterious.
Fremitus is a vibration transmitted through the body. In common medical usage, it usually refers to assessment of the lungs by either the vibration intensity felt on the chest wall and/or heard by a stethoscope on the chest wall with certain spoken words, although there are several other types.
David Eagleman is an American neuroscientist, author, and science communicator. He teaches neuroscience at Stanford University and is CEO and co-founder of Neosensory, a company that develops devices for sensory substitution. He also directs the non-profit Center for Science and Law, which seeks to align the legal system with modern neuroscience and is Chief Science Officer and co-founder of BrainCheck, a digital cognitive health platform used in medical practices and health systems. He is known for his work on brain plasticity, time perception, synesthesia, and neurolaw.
In physics, sound is a vibration that propagates as an acoustic wave through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the reception of such waves and their perception by the brain. Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of 17 meters (56 ft) to 1.7 centimeters (0.67 in). Sound waves above 20 kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound. Different animal species have varying hearing ranges.
The Archive of Applied Mechanics is a peer-reviewed scientific journal established in 1929 as Ingenieur-Archiv by R. Grammel. It obtained its current name in 1991 and is published by Springer. The journal covers research findings on the performance of construction materials. The editor in chief is Jörg Schröder.
Marco Amabili is a chair professor in the School of Engineering at Westlake University in Hangzhou, China. He is also an Emeritus Distinguished James McGill professor at the Department of Mechanical Engineering at McGill University, Montreal, Québec, Canada.
The voiceless bilabial trill is a type of consonantal sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is ⟨ʙ̥⟩. The X-SAMPA symbol is B\_0
Vibrational Spectroscopy is a bi-monthly peer-reviewed scientific journal covering all aspects of Raman spectroscopy, infrared spectroscopy and near infrared spectroscopy. Publication began in December 1990 under the original editors Jeanette G. Grasselli and John van der Maas. The current editor-in-chief is Keith C. Gordon. In addition to research articles and communications, review articles are also published in the journal.
