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A pop filter, pop shield or pop screen is a noise protection filter for microphones, typically used in a recording studio. It serves to reduce or eliminate popping sounds caused by the mechanical impact of fast-moving air on the microphone from plosives during recorded speech and singing. Pop filters can also keep saliva off the microphone during recording.
Popping sounds occur particularly in the pronunciation of aspirated plosives (such as the first 'p' in the English word "popping"). Other plosives can be 't', 'k', 'd', 'b', and 'g' sounds. The popping sound recorded by a microphone has two components: the high-frequency component, caused by air moving past the grille or other parts of the microphone body; and the low-frequency component, caused by air impacting the diaphragm. [1] Mechanical and electrical saturation (e.g. clipping) can also play a role depending on the amount of headroom designed into these systems.
A typical pop filter is composed of one or more layers of acoustically semi-transparent material such as woven nylon stretched over a circular frame, and often includes a clamp and a flexible mounting bracket. Metal pop filters use a fine mesh metal screen in place of the nylon. Some studio condenser microphones have an integral pop filter built into their design.
Metal pop filters are durable and designed with wider holes having less effect on high frequencies.
An improvised pop shield, functionally identical to the professional units, can be made with material from tights or stockings stretched over a kitchen sieve, embroidery hoop or a loop of wire such as a bent clothes hanger. It is important that the pop shield not be attached directly to the microphone as vibrations will be transmitted from the shield to the microphone.
Pop filters are designed to attenuate the energy of the plosive, which otherwise might exceed the design input capacity of the microphone, leading to clipping. In effect, the plosive's discrete envelope of sound energy is intercepted and broken up by the strands of the filter material before it can impinge on, and momentarily distort, the sensitive diaphragm of the microphone. Pop filters do not appreciably affect hissing sounds or sibilance, for which de-essing is used.
Additionally, a pop filter can protect against the accumulation of saliva on the microphone element. Salts in human saliva are corrosive, so the use of a pop filter may improve the lifespan of the microphone. [2]
A pop filter differs from a microphone windscreen. Pop filters are generally used in a studio environment to help improve the sound quality of the recorded voice, while windscreens are typically used outdoors and get rid of any low distortion. Windscreens are also used by vocalists on stage to reduce plosives and saliva, though they may not be as acoustically transparent as a studio pop filter.
The position of the pop filter depends on the amount of power the artist is going to communicate while recording. The position of the pop filter is different in different recording situations, with a further position from the microphone causing fewer pop sounds. More distance means increasing the microphone gain and gaining more room noise. Normally, to get good quality, the pop filter should be placed about 2–6 inches (5–15 cm) away from the microphone. [3]
In signal processing, distortion is the alteration of the original shape of a signal. In communications and electronics it means the alteration of the waveform of an information-bearing signal, such as an audio signal representing sound or a video signal representing images, in an electronic device or communication channel.
A loudspeaker is an electroacoustic transducer that converts an electrical audio signal into a corresponding sound. A speaker system, also often simply referred to as a speaker or loudspeaker, comprises one or more such speaker drivers, an enclosure, and electrical connections possibly including a crossover network. The speaker driver can be viewed as a linear motor attached to a diaphragm which couples that motor's movement to motion of air, that is, sound. An audio signal, typically from a microphone, recording, or radio broadcast, is amplified electronically to a power level capable of driving that motor in order to reproduce the sound corresponding to the original unamplified electronic signal. This is thus the opposite function to the microphone; indeed the dynamic speaker driver, by far the most common type, is a linear motor in the same basic configuration as the dynamic microphone which uses such a motor in reverse, as a generator.
A hydrophone is a microphone designed to be used underwater for recording or listening to underwater sound. Most hydrophones are based on a piezoelectric transducer that generates an electric potential when subjected to a pressure change, such as a sound wave.
A microphone, colloquially called a mic, is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public events, motion picture production, live and recorded audio engineering, sound recording, two-way radios, megaphones, and radio and television broadcasting. They are also used in computers for recording voice, speech recognition, VoIP, and for other purposes such as ultrasonic sensors or knock sensors.
Audio feedback is a positive feedback situation that may occur when an acoustic path exists between an audio input and an audio output. In this example, a signal received by the microphone is amplified and passed out of the loudspeaker. The sound from the loudspeaker can then be received by the microphone again, amplified further, and then passed out through the loudspeaker again. The frequency of the resulting howl is determined by resonance frequencies in the microphone, amplifier, and loudspeaker, the acoustics of the room, the directional pick-up and emission patterns of the microphone and loudspeaker, and the distance between them. The principles of audio feedback were first discovered by Danish scientist Søren Absalon Larsen, hence it is also known as the Larsen effect.
Headphones are a pair of small loudspeaker drivers worn on or around the head over a user's ears. They are electroacoustic transducers, which convert an electrical signal to a corresponding sound. Headphones let a single user listen to an audio source privately, in contrast to a loudspeaker, which emits sound into the open air for anyone nearby to hear. Headphones are also known as earphones or, colloquially, cans. Circumaural and supra-aural headphones use a band over the top of the head to hold the speakers in place. Another type, known as earbuds or earpieces consist of individual units that plug into the user's ear canal. A third type are bone conduction headphones, which typically wrap around the back of the head and rest in front of the ear canal, leaving the ear canal open. In the context of telecommunication, a headset is a combination of headphone and microphone.
A recording studio is a specialized facility for recording and mixing of instrumental or vocal musical performances, spoken words, and other sounds. They range in size from a small in-home project studio large enough to record a single singer-guitarist, to a large building with space for a full orchestra of 100 or more musicians. Ideally, both the recording and monitoring spaces are specially designed by an acoustician or audio engineer to achieve optimum acoustic properties.
A sound reinforcement system is the combination of microphones, signal processors, amplifiers, and loudspeakers in enclosures all controlled by a mixing console that makes live or pre-recorded sounds louder and may also distribute those sounds to a larger or more distant audience. In many situations, a sound reinforcement system is also used to enhance or alter the sound of the sources on the stage, typically by using electronic effects, such as reverb, as opposed to simply amplifying the sources unaltered.
In the field of acoustics, a diaphragm is a transducer intended to inter-convert mechanical vibrations to sounds, or vice versa. It is commonly constructed of a thin membrane or sheet of various materials, suspended at its edges. The varying air pressure of sound waves imparts mechanical vibrations to the diaphragm which can then be converted to some other type of signal; examples of this type of diaphragm are found in microphones and the human eardrum. Conversely a diaphragm vibrated by a source of energy beats against the air, creating sound waves. Examples of this type of diaphragm are loudspeaker cones and earphone diaphragms and are found in air horns.
Mains hum, electric hum, cycle hum, or power line hum is a sound associated with alternating current which is twice the frequency of the mains electricity. The fundamental frequency of this sound is usually double that of fundamental 50/60 Hz, i.e. 100/120 Hz, depending on the local power-line frequency. The sound often has heavy harmonic content above 50/60 Hz. Because of the presence of mains current in mains-powered audio equipment as well as ubiquitous AC electromagnetic fields from nearby appliances and wiring, 50/60 Hz electrical noise can get into audio systems, and is heard as mains hum from their speakers. Mains hum may also be heard coming from powerful electric power grid equipment such as utility transformers, caused by mechanical vibrations induced by magnetostriction in magnetic core. Onboard aircraft the frequency heard is often higher pitched, due to the use of 400 Hz AC power in these settings because 400 Hz transformers are much smaller and lighter.
The Shure SM58 is a professional cardioid dynamic microphone, commonly used in live vocal applications. Produced since 1966 by Shure Incorporated, it has built a reputation among musicians for its durability and sound, and is still the industry standard for live vocal performance microphones. The SM58 is the most popular live vocal microphone in the world. It is a development of the SM57 microphone, which is another industry standard for both live and recorded music. In both cases, SM stands for studio microphone.
The Shure SM57 is a low-impedance cardioid dynamic microphone made by Shure Incorporated and commonly used in live sound reinforcement and studio recording. It is one of the best-selling microphones in the world. It is used extensively in amplified music and has been used for speeches by every U.S. president since its introduction in 1965. In 2004, honoring its four decades of "solid, dependable performance", it was inducted into the first-ever TEC Awards TECnology Hall of Fame.
The history of sound recording - which has progressed in waves, driven by the invention and commercial introduction of new technologies — can be roughly divided into four main periods:
Analysis of sound and acoustics plays a role in such engineering tasks as product design, production test, machine performance, and process control. For instance, product design can require modification of sound level or noise for compliance with standards from ANSI, IEC, and ISO. The work might also involve design fine-tuning to meet market expectations. Here, examples include tweaking an automobile door latching mechanism to impress a consumer with a satisfying click or modifying an exhaust manifold to change the tone of an engine's rumble. Aircraft designers are also using acoustic instrumentation to reduce the noise generated on takeoff and landing.
There are a number of well-developed microphone techniques used for recording musical, film, or voice sources or picking up sounds as part of sound reinforcement systems. The choice of technique depends on a number of factors, including:
The lip-ribbon microphone is a type of ribbon microphone designed specially for use by live news reporters or sports commentators. Organisations such as the BBC, CBS and ABC use lip-ribbon microphones to cover events including motor racing, wrestling, processions and demonstrations.
Equalization, or simply EQ, in sound recording and reproduction is the process of adjusting the volume of different frequency bands within an audio signal. The circuit or equipment used to achieve this is called an equalizer.
The Shure SM7 is a professional cardioid dynamic microphone, commonly used in broadcasting applications since 1973. Designed by Shure, it has been described as an "iconic" industry standard microphone for its focused, directional sound and its widespread adoption in radio, television and recording studios. In 2007–2008, the SM7B model became popular for professional podcasting.
The Sennheiser MD 421 is a German cardioid dynamic microphone, widely used for speech in broadcasting and for music in live concerts and the recording studio. Introduced in 1960, the internal large-diaphragm transducer element of the MD 421 is still produced unchanged by Sennheiser. The MD 421 is considered a classic, an industry standard. More than 500,000 units have been sold.
The Electro-Voice RE20 is an American professional cardioid dynamic microphone, commonly used in broadcasting applications since 1968. Designed by Electro-Voice using the company's patented Variable-D technology and a large-diaphragm element, it has been described as an industry standard "iconic" microphone for its natural sound and its wide usage in radio, television and recording studios. In 2015, the RE20 was inducted into the TEC Awards Technology Hall of Fame.
