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Digital Delay Line
A digital delay line is a discrete element in digital filter theory, which allows a Signalling (telecommunications), signal to be delayed by a number of sample (signal), samples. If the delay is an integer multiple of samples, digital delay lines are often implemented as circular buffers. This means that integer delays can be computed very efficiently. The delay by one sample is notated \mathrm^ and delays of N samples is notated as \mathrm^ motivated by the role the z-transform plays in describing digital filter structures. If a delay is not an integer of a sample additional filters are applied to account for the fraction of delay different from an integer. Hence delay lines with non-integer delay are called ''fractional delay lines''. Digital delay lines were first used to compensate for the speed of sound in air in 1973 to provide appropriate delay times for the distant speaker towers at Summer Jam at Watkins Glen in New York, with 600,000 people in the audience. New Jersey comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Filter
In signal processing, a digital filter is a system that performs mathematical operations on a sampled, discrete-time signal to reduce or enhance certain aspects of that signal. This is in contrast to the other major type of electronic filter, the analog filter, which is typically an electronic circuit operating on continuous-time analog signals. A digital filter system usually consists of an analog-to-digital converter (ADC) to sample the input signal, followed by a microprocessor and some peripheral components such as memory to store data and filter coefficients etc. Program Instructions (software) running on the microprocessor implement the digital filter by performing the necessary mathematical operations on the numbers received from the ADC. In some high performance applications, an FPGA or ASIC is used instead of a general purpose microprocessor, or a specialized digital signal processor (DSP) with specific paralleled architecture for expediting operations such as filter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Room Acoustics
Room acoustics is a subfield of acoustics dealing with the behaviour of sound in enclosed or partially-enclosed spaces. The architectural details of a room influences the behaviour of sound waves within it, with the effects varying by frequency. Acoustic reflection, diffraction, and diffusion can combine to create audible phenomena such as room modes and standing waves at specific frequencies and locations, echos, and unique reverberation patterns. Frequency zones The way that sound behaves in a room can be broken up into roughly four different frequency zones: *The first zone is below the frequency that has a wavelength of twice the longest length of the room. In this zone, sound behaves very much like changes in static air pressure. *Above that zone, until wavelengths are comparable to the dimensions of the room, room resonances dominate. This transition frequency is popularly known as the Schroeder frequency, or the cross-over frequency and it differentiates the low fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wind Instruments
A wind instrument is a musical instrument that contains some type of resonator (usually a tube) in which a column of air is set into vibration by the player blowing into (or over) a mouthpiece set at or near the end of the resonator. The pitch of the vibration is determined by the length of the tube and by manual modifications of the effective length of the vibrating column of air. In the case of some wind instruments, sound is produced by blowing through a reed; others require buzzing into a metal mouthpiece, while yet others require the player to blow into a hole at an edge, which splits the air column and creates the sound. Methods for obtaining different notes * Using different air columns for different tones, such as in the pan flute. These instruments can play several notes at once. * Changing the length of the vibrating air column by changing the length of the tube through engaging valves ''(see rotary valve, piston valve)'' which route the air through additional tubing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
String Instruments
String instruments, stringed instruments, or chordophones are musical instruments that produce sound from vibrating strings when a performer plays or sounds the strings in some manner. Musicians play some string instruments by plucking the String (music), strings with their fingers or a plectrum—and others by hitting the strings with a light wooden hammer or by rubbing the strings with a bow (music), bow. In some keyboard (music), keyboard instruments, such as the harpsichord, the musician presses a key that plucks the string. Other musical instruments generate sound by striking the string. With bowed instruments, the player pulls a rosined horsehair bow across the strings, causing them to vibrate. With a hurdy-gurdy, the musician cranks a wheel whose rosined edge touches the strings. Bowed instruments include the string section instruments of the orchestra in Western classical music (violin, viola, cello and double bass) and a number of other instruments (e.g., viols and V ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sound Synthesis
A synthesizer (also spelled synthesiser) is an electronic musical instrument that generates audio signals. Synthesizers typically create sounds by generating waveforms through methods including subtractive synthesis, additive synthesis and frequency modulation synthesis. These sounds may be altered by components such as filters, which cut or boost frequencies; envelopes, which control articulation, or how notes begin and end; and low-frequency oscillators, which modulate parameters such as pitch, volume, or filter characteristics affecting timbre. Synthesizers are typically played with keyboards or controlled by sequencers, software or other instruments, and may be synchronized to other equipment via MIDI. Synthesizer-like instruments emerged in the United States in the mid-20th century with instruments such as the RCA Mark II, which was controlled with punch cards and used hundreds of vacuum tubes. The Moog synthesizer, developed by Robert Moog and first sold in 1964 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Waveguide Synthesis
Digital waveguide synthesis is the synthesis of audio using a digital waveguide. Digital waveguides are efficient computational models for physical media through which acoustic waves propagate. For this reason, digital waveguides constitute a major part of most modern physical modeling synthesizers. A lossless digital waveguide realizes the discrete form of d'Alembert's solution of the one-dimensional wave equation as the superposition of a right-going wave and a left-going wave, :y(m,n) = y^(m-n) + y^(m+n) where y^ is the right-going wave and y^ is the left-going wave. It can be seen from this representation that sampling the function y at a given point m and time n merely involves summing two delayed copies of its traveling waves. These traveling waves will reflect at boundaries such as the suspension points of vibrating strings or the open or closed ends of tubes. Hence the waves travel along closed loops. Digital waveguide models therefore comprise digital delay lines ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Effects Unit
An effects unit or effects pedal is an electronic device that alters the sound of a musical instrument or other audio source through audio signal processing. Common effects include distortion/overdrive, often used with electric guitar in electric blues and rock music; dynamic effects such as volume pedals and compressors, which affect loudness; filters such as wah-wah pedals and graphic equalizers, which modify frequency ranges; modulation effects, such as chorus, flangers and phasers; pitch effects such as pitch shifters; and time effects, such as reverb and delay, which create echoing sounds and emulate the sound of different spaces. Most modern effects use solid-state electronics or digital signal processors. Some effects, particularly older ones such as Leslie speakers and spring reverbs, use mechanical components or vacuum tubes. Effects are often used as stompboxes, typically placed on the floor and controlled with footswitches. They may also be built into guita ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Musical Instruments
A musical instrument is a device created or adapted to make musical sounds. In principle, any object that produces sound can be considered a musical instrument—it is through purpose that the object becomes a musical instrument. A person who plays a musical instrument is known as an instrumentalist. The history of musical instruments dates to the beginnings of human culture. Early musical instruments may have been used for rituals, such as a horn to signal success on the hunt, or a drum in a religious ceremony. Cultures eventually developed composition and performance of melodies for entertainment. Musical instruments evolved in step with changing applications and technologies. The date and origin of the first device considered a musical instrument is disputed. The oldest object that some scholars refer to as a musical instrument, a simple flute, dates back as far as 50,000 - 60,000 years. Some consensus dates early flutes to about 40,000 years ago. However, most historians be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shift Register
A shift register is a type of digital circuit using a cascade of flip-flops where the output of one flip-flop is connected to the input of the next. They share a single clock signal, which causes the data stored in the system to shift from one location to the next. By connecting the last flip-flop back to the first, the data can cycle within the shifters for extended periods, and in this form they were used as a form of computer memory. In this role they are very similar to the earlier delay-line memory systems and were widely used in the late 1960s and early 1970s to replace that form of memory. In most cases, several parallel shift registers would be used to build a larger memory pool known as a "bit array". Data was stored into the array and read back out in parallel, often as a computer word, while each bit was stored serially in the shift registers. There is an inherent trade-off in the design of bit arrays; putting more flip-flops in a row allows a single shifter to store mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Signalling (telecommunications)
In telecommunication, signaling is the use of signals for controlling communications. This may constitute an information exchange concerning the establishment and control of a telecommunication circuit and the management of the network. Classification Signaling systems may be classified based on several principal characteristics. In-band and out-of-band signaling In the public switched telephone network (PSTN), in-band signaling is the exchange of call control information within the same physical channel, or within the same frequency band, that the telephone call itself is using. An example is dual-tone multi-frequency signaling (DTMF), which is used on most telephone lines to customer premises. Out-of-band signaling is telecommunication signaling on a dedicated channel separate from that used for the telephone call. Out-of-band signaling has been used since Signaling System No. 6 (SS6) was introduced in the 1970s, and also in Signalling System No. 7 (SS7) in 1980 which became ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eventide, Inc
Eventide, Inc. (also known earlier as Eventide Clock Works Inc.) is an American audio, broadcast and communications company whose audio division manufactures digital audio processors, digital signal processor (DSP) software, and guitar effects. Eventide was one of the first companies to manufacture digital audio processors, and its products are mainstays in sound recording and reproduction, post production, and broadcast studios. Beginnings Eventide was founded by recording engineer Stephen Katz, inventor Richard Factor, and businessman/patent attorney Orville Greene. The business was founded in the basement of the Sound Exchange, a recording studio located at 265 West 54th Street in New York City and owned by Greene. When Katz needed to rewind the analog tape back to a specific point on their Ampex MM1000 multitrack recorder, but limited space in the studio did not allow for a tape op (a person who would operate the tape recorder on behalf of the sound engineer), Katz asked Fact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Summer Jam At Watkins Glen
The Summer Jam at Watkins Glen was a July 1973 rock festival outside Watkins Glen, New York, that featured the Allman Brothers Band, Grateful Dead and the Band. The July 28, 1973 event long held the Guinness Book of World Records entry for "largest audience at a pop festival," with an estimated 600,000 fans in attendance at the Watkins Glen Grand Prix Raceway. Approximately 150,000 tickets were purchased in advance, the rest being admitted in what became a "free concert". History The concert was produced by Shelly Finkel and Jim Koplik, two promoters who had organized a successful Grateful Dead concert at Dillon Stadium, Hartford, Connecticut, in 1972. At that show the Grateful Dead were joined on-stage by Dickey Betts, Berry Oakley, and Jai Johanny Johanson, members of the Allman Brothers Band. This impromptu jam planted the seeds that would eventually spawn the "Summer Jam" concert in Watkins Glen, New York. Similar to the 1969 Woodstock Festival, an enormous traffic jam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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