Audio Processing

Topics: Digital signal processing, Sound, Audio signal processing Pages: 5 (1433 words) Published: February 25, 2013
Audio Processing (audio signal processing)
-sometimes referred to as audio processing, is the intentional alteration of auditory signals, or sound, often through an audio effect or effects unit. As audio signals may be electronically represented in either digital or analog format, signal processing may occur in either domain. Analog processors operate directly on the electrical signal, while digital processors operate mathematically on the digital representation of that signal. What is sound?

* is a longitudinal displacement wave that propagates through air or some other medium. Sound waves are defined using two attributes: * Amplitude – the amplitude of a sound wave is a gauge of pressure change, measured in decibels (dB). * Frequency – is denoted as Hertz (Hz), or cycles per second. We can hear sounds in the frequency range between 20Hz to 20000Hz. Audio signals are sound waves—longitudinal waves which travel through air, consisting of compressions and rarefactions. These audio signals are measured in decibels. Audio processing was necessary for early radio broadcasting, as there were many problems with studio to transmitter links. -------------------------------------------------

Analog signals
"Analog" indicates something that is mathematically represented by a set of continuous values; for example, the analog clock uses constantly-moving hands on a physical clock face, where moving the hands directly alters the information that clock is providing. Thus, an analog signal is one represented by a continuous stream of data, in this case along an electrical circuit in the form of voltage, current or charge changes (compare with digital signals below). Analog signal processing (ASP) then involves physically altering the continuous signal by changing the voltage or current or charge via various electrical means. Historically, before the advent of widespread digital technology, ASP was the only method by which to manipulate a signal. Since that time, as computers and software became more advanced, digital signal processing has become the method of choice.

Digital signal
A digital representation expresses the pressure wave-form as a sequence of symbols, usually binary numbers. This permits signal processing using digital circuits such as microprocessors andcomputers. Although such a conversion can be prone to loss, most modern audio systems use this approach as the techniques of digital signal processing are much more powerful and efficient than analog domain signal processing

Application areas
Processing methods and application areas include storage, level compression, data compression, transmission, enhancement (e.g., equalization, filtering, noise cancellation, echo or reverbremoval or addition, etc.) [edit]Audio broadcasting

Audio broadcasting (be it for television or audio broadcasting) is perhaps[weasel words] the biggest market segment (and user area) for audio processing products—globally.[citation needed] Traditionally the most important audio processing (in audio broadcasting) takes place just before the transmitter. Studio audio processing is limited in the modern era due to digital audio systems (mixers, routers) being pervasive in the studio. In audio broadcasting, the audio processor must

* prevent overmodulation, and minimize it when it occurs * compensate for non-linear transmitters, more common with medium wave and shortwave broadcasting * adjust overall loudness to desired level

* correct errors in audio levels
Audio unprocessed by reverb and delay is metaphorically referred to as "dry", while processed audio is referred to as "wet".[3] * echo - to simulate the effect of reverberation in a large hall or cavern, one or several delayed signals are added to the original signal. To be...
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