Alteration

A prepared piano is a piano which has had its sound altered by placing objects between or on the strings or on the hammers or dampers. The idea of altering an instrument’s timbre through the use of external objects has been applied to instruments other than the piano, such as the guitar. Although it is possible to prepare an upright piano, it is far easier, and far more common, on a grand piano.

A composer using prepared piano extensively was John Cage, who is often credited with inventing the instrument. He first prepared a piano when he was commissioned to write music for Bacchanale, a dance by Syvilla Fort in 1938. For some time previously, Cage had been writing exclusively for a percussion ensemble, but the hall where Fort’s dance was to be staged had no room for a percussion group. The only instrument available was a single grand piano.

After some consideration, Cage said that he realized it was possible to place in the hands of a single pianist the equivalent of an entire percussion orchestra. With just one musician, you can really do an unlimited number of things on the inside of the piano if you have at your disposal an exploded keyboard. Cage would often quip that by preparing a piano he left it in better condition than he found it.

In Cage’s use, the preparations are typically nuts, bolts and pieces of rubber to be lodged between and entwined around the strings. Some preparations make duller, more percussive sounds than usual, while others create sonorous bell-like tones. Additionally, the individual parts of a preparation like a nut loosely screwed onto a bolt will vibrate themselves, adding their own unique sound.

By placing the preparation between two of the strings on a note which has three strings assigned to it, it is possible to change the timbre of that note by depressing the soft pedal on the piano, which moves the hammers so they strike only two strings instead of all three. Other prepared piano sounds can be reminiscent of mbiras, marimbas, bells, wood blocks, Indonesian gamelan instruments, or many other sounds less easily defined.

American composer Chris Brown created a type of prepared electric piano, the Gazamba from the shell of a Wurlitzer electric piano. American composer Eric Glick Rieman has composed extensively for prepared Fender Rhodes pianos. Ross Bolleter has taken the idea into an innovative direction, exploring the use of ruined pianos, or pianos decayed by weather and time.

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Influence

A gamelan is a musical ensemble from Indonesia, typically from the islands of Bali or Java, featuring a variety of instruments such as metallophones, xylophones, drums and gongs. The word comes from the Javanese word “gamel” meaning to strike or hammer, and the suffix “an”, which makes the root a collective noun.

The term refers more to the set of instruments than to the players of those instruments. A gamelan is a set of instruments as a distinct entity, built and tuned to stay together. Instruments from different gamelan are generally not interchangeable.

In Javanese mythology, the gamelan was created in AD 230. The god who ruled as king of all Java from a palace on Mount Lawu needed a signal to summon the gods, and thus invented the gong. For more complex messages, he invented two other Gongs, thus forming the basis of the original gamelan set.

The gamelan predates the Hindu-Buddhist culture that dominated Indonesia in its earliest records, and instead represents a native art form. In contrast to the Indian influence in other art forms, the only obvious Indian influence in gamelan music is in the Javanese style of singing.

In Indonesia, gamelan usually accompanies dance, puppet performances, or rituals and ceremonies. Typically players in the gamelan will be familiar with dance moves and poetry, while dancers are able to play in the ensemble. In wayang puppet performances, the puppeteer must have a thorough knowledge of gamelan, as he gives the cues for the music.

Gamelan’s role in rituals is so important that there is a Javanese saying that “It’s not official until the gong is hung.” Certain gamelans are associated with specific rituals, such as the Gamelan Sekaten, which is used in celebration of Muhammad’s birthday. In Bali, almost all religious rituals include gamelan performance. Gamelan is also used in the ceremonies of the Catholic church in Indonesia.

Certain pieces are designated for starting and ending performances or ceremonies. When a “leaving” piece is begun, the audience will know that the event is nearly finished and will begin to leave. Certain pieces are also believed to possess magic powers, and can be used to ward off evil spirits.

There is an increasing amount of gamelan outside Indonesia. There are even forms of gamelan that have originated outside Indonesia, such as American gamelan and Malay Gamelan in Malaysia.

There are also professional American gamelan ensembles. Gamelan Son of Lion is a group that focuses on newly composed music by both the members of the group and invited composers from around the world. Gamelan Kori Mas performs Balinese music on bamboo instruments in the San Francisco bay area.

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Utterance

Acoustic phonetics is a subfield of phonetics which deals with acoustic aspects of speech sounds. It investigates properties such as the mean squared amplitude of a waveform, its duration, its fundamental frequency or other properties of its frequency spectrum, and to abstract linguistic concepts like phrases and utterances.

The study of acoustic phonetics was greatly enhanced in the late 19th century by the invention of the Edison phonograph. The phonograph allowed the speech signal to be recorded and then later processed and analyzed. By replaying the same speech signal from the phonograph several times, filtering it each time with a different filter, a spectrogram or graphic image of the speech recording could be created.

A series of papers by Ludimar Hermann investigated the spectral properties of vowels and consonants using the Edison phonograph, and it was in these papers that the term formant was first introduced. Hermann also played back vowel recordings made with the Edison phonograph at different speeds in an effort to distinguish between varying theories of vowel production.

Further advances in acoustic phonetics were made possible by the development of the telephone industry. During World War II, work at the Bell Telephone Laboratories greatly facilitated the systematic study of the spectral properties of periodic and aperiodic speech sounds, vocal tract resonances and vowel formants, voice quality and prosody.

On a theoretical level, acoustic phonetics advanced greatly when it became clear that speech acoustics could be modeled in a way analogous to electrical circuits. During the early 1900s, Lord Rayleigh was among the first to recognize that the new electric theory could be used in acoustics, but it was not until 1941 that the circuit model was effectively used. In 1952, the book Preliminaries to Speech Analysis was published, tying acoustic phonetics and phonological theory together. This was followed in 1960 by Gunnar Fant’s Acoustic Theory of Speech Production, which has remained the major theoretical foundation for speech acoustic research in both the academy and industry.

Unification

Harry Partch was an American composer and instrument creator. He was one of the first twentieth century composers to work extensively and systematically with microtonal scales, writing much of his music for custom made instruments that he built himself. Partch is famous for his 43 tone scale, even though he used many different scales in his work and the number of divisions is theoretically infinite.

He began to compose at an early age, using the equal tempered chromatic scale, the tuning system most common in Western music. However, Partch grew frustrated with what he felt were imperfections of the standard system of musical tuning, believing that this system was unsuitable for reflecting the subtle melodic contours of dramatic speech.

Interested in the potential musicality of speech, Partch invented and constructed instruments that could underscore the intoning voice, and he developed musical notations that accurately instructed players as to how to play the instruments.

The compositional apex of Partch’s life came with the completion of Delusion of the Fury, a ritual theater piece that unifies musicians, dancers, and mimes into a corporeal performance. Built upon the timeless theme of life and death, Delusion of the Fury is based on two Japanese noh plays and an African folktale

Partch’s instruments have been housed in the Harry Partch Instrumentarium at Montclair State University in Montclair, New Jersey since 1999. In 2004, the instruments crossed campus into the newly constructed Alexander Kasser Theater, which provides a large studio space in the basement. Concerts by Newband and MSU’s Harry Partch Ensemble may be viewed several times a year in this concert hall.

Noise

Stochastic resonance is observed when noise added to a system improves the system’s performance in some fashion. More technically, stochastic resonance occurs if the signal to noise ratio of a nonlinear system or device increases for moderate values of noise intensity.

It was discovered and proposed for the first time in 1981 to explain the periodic recurrence of ice ages. Since then, the same principle has been applied in a wide variety of systems. Currently, stochastic resonance is commonly invoked when noise and nonlinearity concur to determine an increase of order in the system response.

Stochastic resonance has been observed in a wide variety of experiments involving electronic circuits, chemical reactions, semiconductor devices, nonlinear optical systems, magnetic systems and superconducting quantum interference devices (SQUID). Of special interest are the neurophysiological experiments on stochastic resonance, three popular examples of which are the mechanoreceptor cells of crayfish, the sensory hair cells of cricket and human visual perception.

Computationally, neurons exhibit stochastic resonance because of non linearities in their processing. Stochastic resonance has yet to be fully explained in biological systems, but neural synchrony in the brain, specifically in the Gamma wave frequency, has been suggested as a possible neural mechanism for stochastic resonance by researchers who have investigated the perception of subconscious visual sensation.

Stochastic resonance based techniques have been used to create a novel class of medical devices, such as vibrating insoles, for enhancing sensory and motor function in the elderly, patients with diabetic neuropathy, and patients with stroke.

A related phenomenon is dithering applied to analog signals before analog to digital conversion. Stochastic resonance can be used to measure transmittance amplitudes below an instrument’s detection limit. If Gaussian noise is added to a subthreshold or immeasurable signal, then it can be brought into a detectable region. After detection, the noise is removed. In this way, a fourfold improvement in the detection limit can be obtained.

Stochastic resonance is a generic phenomenon. It has to do with the fact that adding noise to certain types of nonlinear systems possessing several simultaneously stable states may improve their ability to process information. As such, it is at the origin of intense interdisciplinary research at the crossroads of nonlinear dynamics, statistical physics, information and communication theories, data analysis, life and medical sciences. It opens tantalizing perspectives, from the development of new families of detectors to brain research. From the fundamental point of view it is still a largely open field of research. Its microscopic foundations have been hardly addressed, its quantum counterpart needs to be further elucidated, and its relevance in complex transition phenomena remains to be explored.

Unisonance

The Pacific Tree Frog is a very common species of chorus frog, with a range from the West Coast of the United States to British Columbia in Canada. Living anywhere from sea level up to over 11,000 feet. They live in many types of habitats and reproduce in aquatic settings.

They can reach up to about 5 cm long from snout to urostyle. The males are often smaller than the females and have a dark patch of skin on their throat. This dark patch is the vocal sac which stretches out when a male is calling. These frogs can have highly variable color on their bodies. They can be anywhere from gray, brown, tan or bright green and can even change between them. They are usually a pale or white color on their bellies. They have many variations of markings on their back and sides that are usually dark and spotty. The one identifiable mark is a dark stripe that goes over the eye from the nose to the shoulder. Their skin is covered in small bumps. They have long legs compared to their bodies and they tend to be slender. Their toes are long and are only very slightly webbed. On the end of each toe, there is a round sticky pad that is used for climbing and sticking to surfaces.

The evolutionary history of these frogs is a very interesting one that has recently been changed to better suit tree frogs. Amphibians themselves are thought to have descended from the lobe finned bony fishes. These fishes had an ossified skeleton and emerged from the water as they developed limb girdles and terrestrial characteristics such as lungs and a neck. It is hard to figure out an exact frog lineage because of the lack of fossil record. The habitat in which these animals lived was moist and decay was quick, which was not helpful in preserving biological clues.

The genus appeared just after the dinosaurs went extinct. They originated in South America and expanded to the north into Mexico and eventually into North America. There was then a rise in sea level and the connection between the northern and southern populations was gone. They have been separate ever since and have become genetically distinct from one another.

One of the most interesting features of these frogs is their ability to change color from brown to green. Previously, it was thought that there were two different fixed colors that an adult tree frog could be. Now it has been found that some of them are actually able to change between the two. They can also change from lighter to darker. These color changing morphs are triggered not by color change in their environment, but a change in background brightness. This type of environmental change would be caused by seasonal fluctuation, and has been shown to be a very useful cryptic survival feature for these frogs.

Pacific tree frogs are most common on the pacific coast of California. They are also found eastward to Montana and Nevada. They love water, but they can also be found upland from ponds, streams, lakes. Their habitat consists of a wide variety of climate and vegetation from sea level to high altitudes. The tree frog makes its home in riparian habitat as well as woodlands, grassland, chaparral, pasture land, and urban areas including back yard ponds.

The Pacific Tree Frog begins mating in early winter to early spring. Since these frogs are so widespread geographically, it is thought that their breeding season is determined by local conditions. When it is time, the males migrate to the water. They all call at the same time very loudly. This lures the females to the water and they mate. The females lay their eggs in clumps of 10-90 and usually put them on and under vegetation and leaf litter in the pond. Females usually lay their eggs in shallow, calm water that has little action around it. If they are not eaten, embryos will hatch into tadpoles within one to three weeks.

The tadpoles feed on periphyton, filamentous algae, diatoms and pollen in and on the surface of the water. They feed using a beak like structure that helps scrape vegetation off surfaces and suction. Metamorphosis follows about two to two and a half months later. Prior to transformation, they stop feeding for a short time while their mouth is transformed from herbivorous to carnivorous. Then the tiny baby frogs emerge from the pond measuring as little as one centimetre. They hunt using their sticky pads to climb on vegetation and other surfaces. Much of their diet consists of spiders, beetles, flies, ants and other insects. They mature very quickly and are likely able to mate in the next season after metamorphosis. Predators include snakes, raccoons, herons, egrets, and other small mammals and reptiles. The tree frog is mostly nocturnal, but can be spotted during the day. It spends a lot of time hiding under rotten logs, rocks, long grasses and leaf litter.

These frogs are the most common frogs on the west coast of North America. Although the Pacific Tree Frog remains abundant and most populations of tree frogs appear healthy, there is some evidence of declines. The cause has not been fully understood, but pollution, the introduction of exotic species and habitat loss are very high on the list of factors. Some ways to stop amphibian declines are by respecting and protecting amphibian habitat as well as supporting laws and legislation that help to do this. Another important way is to help limit pollutants that will end up in amphibian habitat, usually from agriculture and urban run off, by boycotting companies who are heavy pesticide users and by not pouring chemicals or pollutants down storm drains or in amphibian habitat.

Resonance

Helmholtz resonance is the phenomenon of air resonance in a cavity. The name comes from a device created in the 1850s by Hermann Helmholtz to show the height of the various tones. An example of Helmholtz resonance is the sound created when one blows across the top of an empty bottle.

When air is forced into a cavity, the pressure inside increases. Once the external force that forces the air into the cavity disappears, the higher-pressure air inside will flow out. However, this surge of air flowing out will tend to over-compensate, due to the inertia of the air in the neck, and the cavity will be left at a pressure slightly lower than the outside, causing air to be drawn back in. This process repeats with the magnitude of the pressure changes decreasing each time.

This effect is similar to that of a bungee jumper bouncing on the end of a bungee rope, or a mass attached to a spring. Air trapped in the chamber acts as a spring. Changes in the dimensions of the chamber adjust the properties of the spring. A larger chamber would make for a weaker spring, and vice versa.

The air in the the neck of the chamber is the mass. Since it is in motion, it possesses some momentum. A longer port would make for a larger mass, and vice versa. The diameter of the port is related to the mass of air and the volume of the chamber. A port that is too small in area for the chamber volume will choke the flow while one that is too large in area for the chamber volume tends to reduce the momentum of the air in the port.

Helmholtz resonance finds application in internal combustion engines, subwoofers and acoustics. In stringed instruments, such as the guitar and violin, the resonance curve of the instrument has the Helmholtz resonance as one of its peaks, along with other peaks coming from resonances of the vibration of the wood. An ocarina is essentially a Helmholtz resonator where the area of the neck can be easily varied to produce different tones. The West African djembe has a relatively small neck area, giving it a deep bass tone. The djembe may have been used in West African drumming as long as 3,000 years ago, making it much older than our knowledge of the physics involved.

Helmholtz resonators are used in architectural acoustics to reduce undesirable sounds such as standing waves by building a resonator tuned to the problem frequency, thereby eliminating it. This technique is most usually used for low frequency waves.