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audio: Definition and Recommended Links

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A digital representation expresses the pressure wave-form as a sequence of symbols, usually binary numbers, which permits digital signal processing. Whilst all real-world audio signals are continuous-time and continuous-level analog signals, the frequency range of these signals is limited by physical effects, and human ears cannot perceive frequencies below approx. 20 Hz or above approx. 18 kHz (strongly depends on the age of the listener). Therefore, there is no significant loss of information when the analog signal is sampled using a high enough sampling rate (see: sampling). In addition, the dynamic range of audio signals is limited by Noise (sound). More than 130 dB Signal-to-noise ratio is almost impossible to achieve. Therefore, quantization also does not result in significant loss of information either, if done appropriately. Both sampling and quantization must be applied to convert the continuous-time analog signal to a discrete-time digital representation. Although such a conversion is more or less lossy, 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.

Source: Wikipedia (http://en.wikipedia.org/wiki/Audio_signal_processing)

other great electronics sites:ee toolbox site

• • audio
    • A digital representation expresses the pressure wave-form as a sequence of symbols, usually binary numbers, which permits digital signal processing. Whilst all real-world audio signals are continuous-time and continuous-level analog signals, the frequency range of these signals is limited by physical effects, and human ears cannot perceive frequencies below approx. 20 Hz or above approx. 18 kHz (strongly depends on the age of the listener). Therefore, there is no significant loss of information when the analog signal is sampled using a high enough sampling rate (see: sampling). In addition, the dynamic range of audio signals is limited by Noise (sound). More than 130 dB Signal-to-noise ratio is almost impossible to achieve. Therefore, quantization also does not result in significant loss of information either, if done appropriately. Both sampling and quantization must be applied to convert the continuous-time analog signal to a discrete-time digital representation. Although such a conversion is more or less lossy, 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.

      Source: Wikipedia (http://en.wikipedia.org/wiki/Audio_signal_processing)

      (Note: The Electronic Engineers Toolbox provides an alternative set of featured links for this word at http://www.cera2.com/audio.htm)

      Featured Links:

      DSP Algorithms: Download

      A page of downloadable technical papers for acoustics and speech processing applications, along with a Matlab application for room acoustic impulse response mapping.
      http://www.dspalgorithms.com/download.html

      Active Noise Control FAQ

      This FAQ for active noise control, provides history, basics, and answers to many questions on cancelling noise in acoustics, persented ina non-mathematical setting. It includes many analogies to help those who aren't very familiar with DSP or acoustic physics.
      http://www.chrisruckman.com/ancfaq.htm

      Ittiam Systems Unveils its Audio Processing Software for the ARM Cortex-M4 Processor

      Ittiam today announced the availability of audio codecs and post-processing algorithms for the newly released ARM® Cortex™-M4 processor. The ARM Cortex-M4 processor is the most efficient processor of the Cortex-M series for digital signal control applications and has been designed to answer the needs of the motor control, automotive, power management, industrial automation and embedded audio markets. Thanks to its compatibility with...
      http://www.ittiam.com/pages/news/pres-rel-20100223-arm-m4-audio.htm

      Video: Audience, Inc: Cell Phone Noise Reduction Based on the Human Hearing System

      The Audience Voice Processor is the first integrated circuit that is modeled after the most efficient and accurate auditory system, the human hearing system. By understanding the auditory pathway - from the cochlea to the brainstem to the thalamus and cortex - Audience is the first company to deliver a commercial product based on the science of Auditory Scene Analysis (ASA), or the grouping and processing of complex mixtures of sound. Because ...
      http://www.dsp-fpga.com

      Audio Engineering Society

      The Audio Engineering Society, now in its fifth decade, is the only professional society devoted exclusively to audio technology. Its membership of leading engineers, scientists and other authorities has increased dramatically throughout the world. The AES serves its members, the industry and the public by stimulating and facilitating advances in the constantly changing field of audio.
      http://www.aes.org/

      DSP dimension - Stephan M. Sprenger's Audio DSP Pages

      Stephan Sprenger's site include papers, tutorials, FAQs, and links on audio DSP. The articles are well thought out and illustrated and go into considerable depth.
      http://www.dspdimension.com/

      AudioDesignLine.com

      The Audio DesignLine delivers critical technical information focused on the needs and interests of audio electronics engineers and engineering managers. Audio DesignLine is your source for hands-on how-to details, product announcements and reviews, expert advice and analysis, insights into industry trends, and critical news.
      http://www.audiodesignline.com/

      Open Sound World

      Extensible programming environment that allows musicians, sound designers and researchers to process sound in response to expressive real-time control. OSW combines a familiar visual patching paradigm with solid programming-language features such as a strong type system and hierarchical name spaces. OSW also includes an intuitive model for specifying new components
      http://osw.sourceforge.net/

      Open Sound Control

      Open Sound Control (OSC) is a protocol for communication among computers, sound synthesizers, and other multimedia devices that is optimized for modern networking technology. Bringing the benefits of modern networking technology to the world of electronic musical instruments, OSC's advantages include interoperability, accuracy, flexibility, and enhanced organization and documentation. This simple yet powerful protocol provides everything...
      http://opensoundcontrol.org/

      MusicDSP.org

      Musicdsp.org is a collection of data, gathered for the music dsp community. Regards go out to the people on the music-dsp mailing list who provide a constant stream of information and thoughts. Where the music-dsp list site provides the raw information, we at musicdsp.org will do our best to present a selection of this information in a more 'parsed' form.
      http://www.musicdsp.org/

      Explanation: these links are provided as part of our EE glossary project, which seeks to identify the most prominent keywords in embedded systems, embedded software, realtime and rtos, dsp (digital signal processing), system-on-a-chip, microprocessors and microcontrollers, and other constituent elements for embedded systems. While we seek to keep most of the links up-to-date, the user is refered to other primary electronic-based search sites such as: cera2.com, embedded.com, or EDN Magazine. If you have any suggestions of links or definitions, please email!

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