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Loudspeaker Measurement
Loudspeaker measurement is the practice of determining the behaviour of loudspeakers by measuring various aspects of performance. This measurement is especially important because loudspeakers, being transducers, have a higher level of distortion than other audio system components used in playback or sound reinforcement. Anechoic measurement One way to test a loudspeaker requires an anechoic chamber, with an acoustically transparent floor-grid. The measuring microphone is normally mounted on an unobtrusive boom (to avoid reflections) and positioned 1 metre in front of the drive units on the axis with the high-frequency driver. While this can produce repeatable results, such a 'free-space' measurement is not representative of performance in a room, especially a small room. For valid results at low frequencies, a very large anechoic chamber is needed, with large absorbent wedges on all sides. Most anechoic chambers are not designed for accurate measurement down to 20 Hz a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bosch 36W Column Loudspeaker Polar Pattern
Bosch may refer to: People * Bosch (surname) * Hieronymus Bosch (c. 1450 – 1516), painter * Van den Bosch, a Dutch toponymic surname * Carl Bosch, a German chemical engineer and nephew of Robert Bosch * Robert Bosch, founder of Robert Bosch GmbH Places * Bosch (island), a former island in the Wadden Sea * Bosch, Netherlands, a hamlet in North Brabant * 7414 Bosch, a main-belt asteroid named after Carl Bosch * Bosch en Duin, Netherlands * Den Bosch, colloquial name of 's-Hertogenbosch, Netherlands * Villa Bosch, Argentina Arts, entertainment, and media * Harry Bosch, the nickname of Hieronymus Bosch, a fictional detective created by Michael Connelly * ''Bosch'' (TV series), an American TV series based on Connelly's novels * Huis Ten Bosch (theme park), Japan Buildings * Bosch Palace, the official residence of the U.S. Ambassador to Argentina * Huis ten Bosch, an official palace of the Dutch Royal Family in The Hague, Netherlands * Huis Ten Bosch Station, a train station for t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resonance
Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied Periodic function, periodic force (or a Fourier analysis, Fourier component of it) is equal or close to a natural frequency of the system on which it acts. When an Oscillation, oscillating force is applied at a resonant frequency of a dynamic system, the system will oscillate at a higher Amplitude, amplitude than when the same force is applied at other, non-resonant frequencies. Frequencies at which the response amplitude is a relative maximum are also known as resonant frequencies or resonance frequencies of the system. Small periodic forces that are near a resonant frequency of the system have the ability to produce large amplitude oscillations in the system due to the storage of vibrational energy. Resonance phenomena occur with all types of vibrations or waves: there is mechanical resonance, orbital resonance, acoustic resonance, Electromagnetic radiation, electromagnet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parabolic Loudspeaker
A parabolic loudspeaker is a loudspeaker which seeks to focus its sound in coherent plane waves either by reflecting sound output from a speaker driver to a parabolic reflector aimed at the target audience, or by arraying drivers on a parabolic surface. The resulting beam of sound travels farther, with less dissipation in air, than horn loudspeakers, and can be more focused than line array loudspeakers allowing sound to be sent to isolated audience targets.Borgerson, Bruce"Technology Showcase: Focused Loudspeaker Systems."AVInstall, November 1, 2005. Retrieved on August 25, 2009. The parabolic loudspeaker has been used for such diverse purposes as directing sound at faraway targets in performing arts centers and stadia, for industrial testing, for intimate listening at museum exhibits, and as a sonic weapon. Technology A parabolic loudspeaker can send sound farther than traditional loudspeaker designs. The focused waves of a parabolic loudspeaker tend to dissipate in air at about ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loudspeaker Acoustics
Loudspeaker acoustics is a subfield of acoustical engineering concerned with the reproduction of sound and the parameters involved in doing so in actual equipment. Engineers measure the performance of drivers and complete speaker systems to characterize their behavior, often in an anechoic chamber, outdoors, or using time windowed measurement systems -- all to avoid including room effects (e.g., reverberation) in the measurements. Designers use models (from electrical filter theory) to predict the performance of drive units in different enclosures, now almost always based on the work of A N Thiele and Richard Small. Important driver characteristics are: *Frequency response *Off-axis response ( dispersion pattern, lobing) *Sensitivity (dB SPL for 1 watt input) * Maximum power handling * Non-linear distortion * Colouration (i.e., more or less, delayed resonance). It is the performance of a loudspeaker/listening room combination that really matters, as the two interact in multipl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isobaric Loudspeaker
The Isobaric loudspeaker configuration was first introduced by Harry F. Olson in the early 1950s, and refers to systems in which two or more identical woofers (bass drivers) operate simultaneously, with a common body of enclosed air adjoining one side of each diaphragm. In practical applications, they are most often used to improve low-end frequency response without increasing cabinet size, though at the expense of cost and weight. The name is derived from the term Isobar ("equal pressure"), which comes from the Greek word "isobares", meaning "of equal weight". As the word implies, the enclosed air does indeed experience roughly equal pressures from each diaphragm it contacts, but those forces are actually parallel, rather than opposing, so the air is forced to move. Design principles Two identical loudspeakers are coupled to work together as one unit: they are mounted one behind the other in a casing to define a sealed chamber of air in between them. The volume of this "isobar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Directional Sound
Directional Sound refers to the notion of using various devices to create fields of sound which spread less than most (small) traditional loudspeakers. Several techniques are available to accomplish this, and each has its benefits and drawbacks. Ultimately, choosing a directional sound device depends greatly on the environment in which it is deployed as well as the content that will be reproduced. Keeping these factors in mind will yield the best results through any evaluation of directional sound technologies. Systems which guide evacuees during an emergency by the emission of pink noise to the exits are often also called "directional sound" systems. Basic theory In all wave-producing sources, the directivity of any source, at maximum, corresponds to the size of the source compared to the wavelengths it is generating: The larger the source is compared to the wavelength of the sound waves, the more directional beam results . The specific transduction method has no impact o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bandwidth Extension
Bandwidth extension of signal is defined as the deliberate process of expanding the frequency range (bandwidth) of a signal in which it contains an appreciable and useful content, and/or the frequency range in which its effects are such. Its significant advancement in recent years has led to the technology being adopted commercially in several areas including psychacoustic bass enhancement of small loudspeakers and the high frequency enhancement of coded speech and audio. Bandwidth extension has been used in both speech and audio compression applications. The algorithms used in G.729.1 and Spectral Band Replication (SBR) are two of many examples of bandwidth extension algorithms currently in use. In these methods, the low band of the spectrum is encoded using an existing codec, whereas the high band is coarsely parameterized using fewer parameters. Many of these bandwidth extension algorithms make use of the correlation between the low band and the high band in order to predict t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio Quality Measurement
Audio system measurements are a means of quantifying system performance. These measurements are made for several purposes. Designers take measurements so that they can 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio System Measurements
Audio system measurements are a means of quantifying system performance. These measurements are made for several purposes. Designers take measurements so that they can 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 ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio Power
Audio power is the electrical power transferred from an audio amplifier to a loudspeaker, measured in watts. The electrical power delivered to the loudspeaker, together with its efficiency, determines the sound power generated (with the rest of the electrical power being converted to heat). Amplifiers are limited in the electrical energy they can output, while loudspeakers are limited in the electrical energy they can convert to sound energy without being damaged or distorting the audio signal. These limits, or power ratings, are important to consumers finding compatible products and comparing competitors. Power handling In audio electronics, there are several methods of measuring power output (for such things as amplifiers) and power handling capacity (for such things as loudspeakers). Amplifiers Amplifier output power is limited by voltage, current, and temperature: * Voltage: The amp's power supply voltage limits the maximum amplitude of the waveform it can output. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maximum Length Sequence
A maximum length sequence (MLS) is a type of pseudorandom binary sequence. They are bit sequences generated using maximal linear-feedback shift registers and are so called because they are periodic and reproduce every binary sequence (except the zero vector) that can be represented by the shift registers (i.e., for length-''m'' registers they produce a sequence of length 2''m'' − 1). An MLS is also sometimes called an n-sequence or an m-sequence. MLSs are spectrally flat, with the exception of a near-zero DC term. These sequences may be represented as coefficients of irreducible polynomials in a polynomial ring over Z/2Z. Practical applications for MLS include measuring impulse responses (e.g., of room reverberation or arrival times from towed sources in the ocean). They are also used as a basis for deriving pseudo-random sequences in digital communication systems that employ direct-sequence spread spectrum and frequency-hopping spread spectrum transmission s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Correlation
In statistics, correlation or dependence is any statistical relationship, whether causal or not, between two random variables or bivariate data. Although in the broadest sense, "correlation" may indicate any type of association, in statistics it usually refers to the degree to which a pair of variables are ''linearly'' related. Familiar examples of dependent phenomena include the correlation between the height of parents and their offspring, and the correlation between the price of a good and the quantity the consumers are willing to purchase, as it is depicted in the so-called demand curve. Correlations are useful because they can indicate a predictive relationship that can be exploited in practice. For example, an electrical utility may produce less power on a mild day based on the correlation between electricity demand and weather. In this example, there is a causal relationship, because extreme weather causes people to use more electricity for heating or cooling. Howev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
