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Audio Noise Measurement
Audio noise measurement is a process carried out to assess the quality of audio equipment, such as the kind used in recording studios, broadcast engineering, and in-home high fidelity. In audio equipment noise is a low-level hiss or buzz that intrudes on audio output. Every piece of equipment which the recorded signal subsequently passes through will add a certain amount of electronic noise the process of removing this and other noises is called noise reduction. Origins of noise – the need for weighting Microphones, amplifiers and recording systems all add some electronic noise to the signals passing through them, generally described as hum, buzz or hiss. All buildings have low-level magnetic and electrostatic fields in and around them emanating from mains supply wiring, and these can induce hum into signal paths, typically 50 Hz or 60 Hz (depending on the country's electrical supply standard) and lower harmonics. Shielded cables help to prevent this, and on profe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio Equipment
Audio equipment refers to devices that reproduce, record, or process sound. This includes microphones, radio receivers, AV receivers, CD players, tape recorders, amplifiers, mixing consoles, effects units, headphones, and speakers. Audio equipment is widely used in many different scenarios, such as concerts, bars, meeting rooms and the home where there is a need to reproduce, record and enhance sound volume. Electronic circuits considered a part of audio electronics may also be designed to achieve certain signal processing operations, in order to make particular alterations to the signal while it is in the electrical form.Kadis, J. (2011). Introduction to sound recording technology. Informally published manuscript, Stanford Music Department: Center for Computer Research in Music and Acoustics, Stanford University, Stanford, California. Audio signals can be created synthetically through the generation of electric signals from electronic devices. Audio electronics were tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FM Radio
FM broadcasting is a method of radio broadcasting that uses frequency modulation (FM) of the radio broadcast carrier wave. Invented in 1933 by American engineer Edwin Armstrong, wide-band FM is used worldwide to transmit high fidelity, high-fidelity sound over broadcast radio. FM broadcasting offers higher fidelity—more accurate reproduction of the original program sound—than other broadcasting techniques, such as AM broadcasting. It is also less susceptible to Electromagnetic interference, common forms of interference, having less static and popping sounds than are often heard on AM. Therefore, FM is used for most broadcasts of music and general audio (in the audio spectrum). FM radio stations use the very high frequency range of radio frequency, radio frequencies. Broadcast bands Throughout the world, the FM broadcast band falls within the VHF part of the radio spectrum. Usually 87.5 to 108.0 MHz is used, or some portion of it, with few exceptions: * In the Commo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sound Level Meter
A sound level meter (also called sound pressure level meter (SPL)) is used for acoustics, acoustic measurements. It is commonly a hand-held instrument with a microphone. The best type of microphone for sound level meters is the condenser microphone, which combines precision with stability and reliability. The Diaphragm (acoustics), diaphragm of the microphone responds to changes in air pressure caused by sound waves. That is why the instrument is sometimes referred to as a sound pressure level meter (SPL). This movement of the diaphragm, i.e. the sound pressure (unit Pascal (unit), pascal, Pa), is converted into an electrical signal (unit volt, volt, V). While describing sound in terms of sound pressure, a logarithmic conversion is usually applied and the sound pressure ''level'' is stated instead, in decibels (dB), with 0 dB SPL equal to 20 micropascals. A microphone is distinguishable by the voltage value produced when a known, constant root mean square sound pressure is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio Quality Measurement
Audio system measurements are used to quantify audio system performance. These measurements are made for several purposes. Designers take measurements to specify the performance of a piece of equipment. Maintenance engineers make them to ensure equipment is still working to specification, or to ensure that the cumulative defects of an audio path are within limits considered acceptable. Audio system measurements often accommodate psychoacoustic principles to measure the system in a way that relates to human hearing. Subjectivity and frequency weighting Subjectively valid methods came to prominence in consumer audio in the UK and Europe in the 1970s, when the introduction of compact cassette tape, dbx and Dolby noise reduction techniques revealed the unsatisfactory nature of many basic engineering measurements. The specification of weighted CCIR-468 quasi-peak noise, and weighted quasi-peak wow and flutter became particularly widely used and attempts were made to find ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cirrus Logic
Cirrus Logic Inc. is an American fabless semiconductor company, fabless semiconductor supplier that specializes in analog, mixed-signal, and audio Digital signal processor, DSP integrated circuits (ICs). Since 1998, the company's headquarters have been in Austin, Texas. The company's audio processors and audio converters feature in audio and consumer entertainment products, including smartphones, tablets, laptops, digital headsets, automotive entertainment systems, home-theater receivers, and smart home applications, such as smart speakers. The company has over 3,200 customers including Ford, Harman International, Itron, LG, Lenovo, Onkyo, Marantz, Motorola, Panasonic, Pioneer, Samsung, SiriusXM, Sony, Apple, and Vizio. Apple makes up 89% of the company's revenue in 2025. Suhas Patil founded the company as "Patil Systems, Inc." in Salt Lake City in 1981; it adopted the name "Cirrus Logic" when it moved to Silicon Valley in 1984. Cirrus Logic has more than 3,900 patents issued and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamic Range
Dynamics (from Greek δυναμικός ''dynamikos'' "powerful", from δύναμις ''dynamis'' " power") or dynamic may refer to: Physics and engineering * Dynamics (mechanics), the study of forces and their effect on motion Brands and enterprises * Dynamic (record label), an Italian record label in Genoa Mathematics * Dynamical system, a concept describing a point's time dependency ** Topological dynamics, the study of dynamical systems from the viewpoint of general topology * Symbolic dynamics, a method to model dynamical systems Social science * Group dynamics, the study of social group processes especially * Population dynamics, in life sciences, the changes in the composition of a population * Psychodynamics, the study of psychological forces driving human behavior * Social dynamics, the ability of a society to react to changes * Spiral Dynamics, a social development theory Other uses * Dynamics (music), the softness or loudness of a sound or note * DTA Dynami ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Signal-to-noise Ratio
Signal-to-noise ratio (SNR or S/N) is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. SNR is defined as the ratio of signal power to noise power, often expressed in decibels. A ratio higher than 1:1 (greater than 0 dB) indicates more signal than noise. SNR is an important parameter that affects the performance and quality of systems that process or transmit signals, such as communication systems, audio systems, radar systems, imaging systems, and data acquisition systems. A high SNR means that the signal is clear and easy to detect or interpret, while a low SNR means that the signal is corrupted or obscured by noise and may be difficult to distinguish or recover. SNR can be improved by various methods, such as increasing the signal strength, reducing the noise level, filtering out unwanted noise, or using error correction techniques. SNR also determines the maximum possible amount of data that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Standards Institute
The British Standards Institution (BSI) is the Standards organization, national standards body of the United Kingdom. BSI produces technical standards on a wide range of products and services and also supplies standards certification services for business and personnel. History BSI was founded as the Engineering Standards Committee in London in 1901.Robert C McWilliam. BSI: The first hundred years. 2001. Thanet Press. London It subsequently extended its standardization work and became the British Engineering Standards Association in 1918, adopting the name British Standards Institution in 1931 after receiving a Royal charter, Royal Charter in 1929. In 1998 a revision of the Charter enabled the organization to diversify and acquire other businesses, and the trading name was changed to BSI Group. The Group now operates in 195 countries. The core business remains standards and standards related services, although the majority of the Group's revenue comes from management systems ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Electrotechnical Commission
The International Electrotechnical Commission (IEC; ) is an international standards organization that prepares and publishes international standards for all electrical, electronics, electronic and related technologies. IEC standards cover a vast range of technologies from power generation, transmission and distribution to home appliances and office equipment, semiconductors, fibre optics, batteries, solar energy, nanotechnology, and marine energy, as well as many others. The IEC also manages four global conformity assessment systems that certify whether equipment, system or components conform to its international standards. All electrotechnologies are covered by IEC Standards, including energy production and distribution, electronics, magnetics and electromagnetics, electroacoustics, multimedia, telecommunications and medical technology, as well as associated general disciplines such as terminology and symbols, electromagnetic compatibility, measurement and performance, dependa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Telecommunication Union
The International Telecommunication Union (ITU)In the other common languages of the ITU: * * is a list of specialized agencies of the United Nations, specialized agency of the United Nations responsible for many matters related to information and communications technology, information and communication technologies. It was established on 17 May 1865 as the International Telegraph Union, the first formal and permanent international organization. The organization significantly predates the UN, making it the oldest UN agency. Doreen Bogdan-Martin is the Secretary-General of ITU, the first woman to serve as its head. The ITU was initially aimed at helping connect Telegraphy, telegraphic networks between countries, with its mandate consistently broadening with the advent of new communications technologies; it adopted its current name in 1932 to reflect its expanded responsibilities over radio and the telephone. On 15 November 1947, the ITU entered into an agreement with the newly cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ITU-R 468
ITU-R 468 (originally defined in CCIR recommendation 468-4, therefore formerly also known as CCIR weighting; sometimes referred to as CCIR-1k) is a standard relating to noise measurement, widely used when measuring noise in audio systems. The standard, now referred to as ITU-R BS.468-4, defines a weighting filter curve, together with a quasi-peak rectifier having special characteristics as defined by specified tone-burst tests. It is currently maintained by the International Telecommunication Union who took it over from the CCIR. It is used especially in the UK, Europe, and former countries of the British Empire such as Australia and South Africa. It is less well known in the USA where A-weighting has always been used. M-weighting is a closely related filter, an offset version of the same curve, without the quasi-peak detector. Explanation The A-weighting curve was based on the 40 phon equal-loudness contour derived initially by Fletcher and Munson (1933). Originally inco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
