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Vibrate
Vibration () is a mechanical phenomenon whereby oscillations occur about an equilibrium point. Vibration may be deterministic if the oscillations can be characterised precisely (e.g. the periodic motion of a pendulum), or random if the oscillations can only be analysed statistically (e.g. the movement of a tire on a gravel road). Vibration can be desirable: for example, the motion of a tuning fork, the reed in a woodwind instrument or harmonica, a mobile phone, or the cone of a loudspeaker. In many cases, however, vibration is undesirable, wasting energy and creating unwanted sound. For example, the vibrational motions of engines, electric motors, or any mechanical device in operation are typically unwanted. Such vibrations could be caused by imbalances in the rotating parts, uneven friction, or the meshing of gear teeth. Careful designs usually minimize unwanted vibrations. The studies of sound and vibration are closely related (both fall under acoustics). Sound, or press ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuning Fork
A tuning fork is an acoustic resonator in the form of a two-pronged fork with the prongs ( ''tines'') formed from a U-shaped bar of elastic metal (usually steel). It resonates at a specific constant pitch when set vibrating by striking it against a surface or with an object, and emits a pure musical tone once the high overtones fade out. A tuning fork's pitch depends on the length and mass of the two prongs. They are traditional sources of standard pitch for tuning musical instruments. The tuning fork was invented in 1711 by British musician John Shore, sergeant trumpeter and lutenist to the royal court. Description A tuning fork is a fork-shaped acoustic resonator used in many applications to produce a fixed tone. The main reason for using the fork shape is that, unlike many other types of resonators, it produces a very pure tone, with most of the vibrational energy at the fundamental frequency. The reason for this is that the frequency of the first overtone is about ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Woodwind Instrument
Woodwind instruments are a family of musical instruments within the greater category of wind instruments. Common examples include flute, clarinet, oboe, bassoon, and saxophone. There are two main types of woodwind instruments: flutes and reed instruments (otherwise called reed pipes). The main distinction between these instruments and other wind instruments is the way in which they produce sound. All woodwinds produce sound by splitting the air blown into them on a sharp edge, such as a reed or a fipple. Despite the name, a woodwind may be made of any material, not just wood. Common examples of other materials include brass, silver, cane, and other metals such as gold and platinum. The saxophone, for example, though made of brass, is considered a woodwind because it requires a reed to produce sound. Occasionally, woodwinds are made of earthen materials, especially ocarinas. Flutes Flutes produce sound by directing a focused stream of air across the edge of a hole i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reed (music)
A reed (or lamella) is a thin strip of material that vibrates to produce a sound on a musical instrument. Most woodwind instrument reeds are made from '' Arundo donax'' ("Giant cane") or synthetic material. Tuned reeds (as in harmonicas and accordions) are made of metal or synthetics. Musical instruments are classified according to the type and number of reeds. The earliest types of single-reed instruments used idioglottal reeds, where the vibrating reed is a tongue cut and shaped on the tube of cane. Much later, single-reed instruments started using heteroglottal reeds, where a reed is cut and separated from the tube of cane and attached to a mouthpiece of some sort. By contrast, in an uncapped double reed instrument (such as the oboe and bassoon), there is no mouthpiece; the two parts of the reed vibrate against one another. Single reeds Single reeds are used on the mouthpieces of clarinets and saxophones. The back of the reed is flat and is placed against the mouthpiece. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vocal Cords
In humans, the vocal cords, also known as vocal folds, are folds of throat tissues that are key in creating sounds through Speech, vocalization. The length of the vocal cords affects the pitch of voice, similar to a violin string. Open when breathing and vibrating for speech or singing, the folds are controlled via the recurrent laryngeal nerve, recurrent laryngeal branch of the vagus nerve. They are composed of twin infoldings of mucous membrane stretched horizontally, from back to front, across the larynx. They vibration, vibrate, modulating the flow of air being expelled from the lungs during phonation. The 'true vocal cords' are distinguished from the 'false vocal folds', known as vestibular folds or ''ventricular folds'', which sit slightly superior to the more delicate true folds. These have a minimal role in normal phonation, but can produce deep sonorous tones, screams and growls. The length of the vocal fold at birth is approximately six to eight millimeters and grows t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harmonica
The harmonica, also known as a French harp or mouth organ, is a free reed wind instrument used worldwide in many musical genres, notably in blues, American folk music, classical music, jazz, country, and rock. The many types of harmonica include diatonic, chromatic, tremolo, octave, orchestral, and bass versions. A harmonica is played by using the lips and tongue to direct air into or out of one (or more) holes along a mouthpiece (which covers one edge of the harmonica for most of its length). Behind each hole is a chamber containing at least one reed. The most common type of harmonica is a diatonic Richter-tuned instrument with ten air passages and twenty reeds, often called a blues harp. A harmonica reed is a flat, elongated spring typically made of brass, stainless steel, or bronze, which is secured at one end over a slot that serves as an airway. When the free end is made to vibrate by the player's air, the reed alternately blocks and unblocks the airway to produce soun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loudspeaker
A loudspeaker (commonly referred to as a speaker or, more fully, a speaker system) is a combination of one or more speaker drivers, an enclosure, and electrical connections (possibly including a crossover network). The speaker driver is an electroacoustic transducer that converts an electrical audio signal into a corresponding sound. The driver is a linear motor connected to a diaphragm, which transmits the motor's movement to produce sound by moving air. An audio signal, typically originating from a microphone, recording, or radio broadcast, is electronically amplified to a power level sufficient to drive the motor, reproducing the sound corresponding to the original unamplified signal. This process functions as the inverse of a microphone. In fact, the ''dynamic speaker'' driver—the most common type—shares the same basic configuration as a dynamic microphone, which operates in reverse as a generator. The dynamic speaker was invented in 1925 by Edward W. Kellogg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wave
In physics, mathematics, engineering, and related fields, a wave is a propagating dynamic disturbance (change from List of types of equilibrium, equilibrium) of one or more quantities. ''Periodic waves'' oscillate repeatedly about an equilibrium (resting) value at some frequency. When the entire waveform moves in one direction, it is said to be a travelling wave; by contrast, a pair of superposition principle, superimposed periodic waves traveling in opposite directions makes a ''standing wave''. In a standing wave, the amplitude of vibration has nulls at some positions where the wave amplitude appears smaller or even zero. There are two types of waves that are most commonly studied in classical physics: mechanical waves and electromagnetic waves. In a mechanical wave, Stress (mechanics), stress and Strain (mechanics), strain fields oscillate about a mechanical equilibrium. A mechanical wave is a local deformation (physics), deformation (strain) in some physical medium that propa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Engine Balance
Engine balance refers to how the inertial forces produced by moving parts in an internal combustion engine or steam engine are neutralised with counterweights and Balance shaft#Overview, balance shafts, to prevent unpleasant and potentially damaging vibration. The strongest inertial forces occur at crankshaft speed (first-order forces) and balance is mandatory, while forces at twice crankshaft speed (second-order forces) can become significant in some cases. Causes of imbalance Although some components within the engine (such as the connecting rods) have complex motions, all motions can be separated into reciprocating and rotating components, which assists in the analysis of imbalances. Using the example of an inline engine (where the pistons are vertical), the main reciprocating motions are: * Pistons moving upwards/downwards * Connecting rods moving upwards/downwards * Connecting rods moving left/right as they rotate around the crankshaft, however the lateral vibrations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sound
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 frequency, 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 to . 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, allowing some to even hear ultrasounds. Definition Sound is defined as "(a) Oscillation in pressure, stress, particle displacement, particle velocity, etc., propagated in a medium with internal forces (e.g., elastic or viscous), or the superposition of such propagated oscillation. (b) Auditory sen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pendulum
A pendulum is a device made of a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position. When released, the restoring force acting on the pendulum's mass causes it to oscillate about the equilibrium position, swinging back and forth. The time for one complete cycle, a left swing and a right swing, is called the period. The period depends on the length of the pendulum and also to a slight degree on the amplitude, the width of the pendulum's swing. Pendulums were widely used in early mechanical clocks for timekeeping. The regular motion of pendulums was used for timekeeping and was the world's most accurate timekeeping technology until the 1930s. The pendulum clock invented by Christiaan Huygens in 1656 became the world's standard timekeeper, used in homes and offices for 270 years, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ear Drum
In the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear from the middle ear. Its function is to transmit changes in pressure of sound from the air to the ossicles inside the middle ear, and thence to the oval window in the fluid-filled cochlea. The ear thereby converts and amplifies vibration in the air to vibration in cochlear fluid. The malleus bone bridges the gap between the eardrum and the other ossicles. Rupture or perforation of the eardrum can lead to conductive hearing loss. Collapse or retraction of the eardrum can cause conductive hearing loss or cholesteatoma. Structure Orientation and relations The tympanic membrane is oriented obliquely in the anteroposterior, mediolateral, and superoinferior planes. Consequently, its superoposterior end lies lateral to its anteroinferior end. Anatomically, it relates superiorly to the middle cranial fos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Machining Vibrations
In machining, vibrations, also called chatter, are the relative movements between the workpiece and the cutting tool. The vibrations result in waves on the machined surface. This affects typical machining processes, such as turning, milling and drilling, and atypical machining processes, such as grinding. A chatter mark is an irregular surface flaw left by a wheel that is ''out of true'' (off-center) in grinding, or regular marks left when turning a long piece on a lathe, due to machining vibrations. As early as 1907, Frederick W. Taylor described machining vibrations as the most obscure and delicate of all the problems facing the machinist, an observation still true today, as shown in many publications on machining. The explanation of the machine tool regenerative chatter was made by Tobias. S. A. and W. Fishwick in 1958, by modeling the feedback loop between the metal cutting process and the machine tool structure, and came with the stability lobes diagram. The structure s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
