World Library  
Flag as Inappropriate
Email this Article

Audio filter

Article Id: WHEBN0000370157
Reproduction Date:

Title: Audio filter  
Author: World Heritage Encyclopedia
Language: English
Subject: Audio signal processing, Subtractive synthesis, Z.Vex Effects, Sound effect, Techno
Collection: Synthesizer Electronics, Tone, Eq and Filter
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Audio filter

Digital domain parametric equalisation

An audio filter is a frequency dependent amplifier circuit, working in the audio frequency range, 0 Hz to beyond 20 kHz. Many types of filters exist for applications including graphic equalizers, synthesizers, sound effects, CD players and virtual reality systems.

Being a frequency dependent amplifier, in its most basic form, an audio filter is designed to amplify, pass or attenuate (negative amplification) some frequency ranges. Common types include low-pass filters, which pass through frequencies below their cutoff frequencies, and progressively attenuates frequencies above the cutoff frequency. A high-pass filter does the opposite, passing high frequencies above the cutoff frequency, and progressively attenuating frequencies below the cutoff frequency. A bandpass filter passes frequencies between its two cutoff frequencies, while attenuating those outside the range. A band-reject filter, attenuates frequencies between its two cutoff frequencies, while passing those outside the 'reject' range.

An all-pass filter, passes all frequencies, but affects the phase of any given sinusoidal component according to its frequency.

In some applications, such as in the design of graphic equalizers or CD players, the filters are designed according to a set of objective criteria such as pass band, pass band attenuation, stop band, and stop band attenuation, where the pass bands are the frequency ranges for which audio is attenuated less than a specified maximum, and the stop bands are the frequency ranges for which the audio must be attenuated by a specified minimum.

In more complex cases, an audio filter can provide a feedback loop, which introduces resonance (ringing) alongside attenuation. Audio filters can also be designed to provide gain (boost) as well as attenuation.

In other applications, such as with synthesizers or sound effects, the aesthetic of the filter must be evaluated subjectively.

Audio filters can be implemented in analog circuitry as analog filters or in DSP code or computer software as digital filters.

Generically, the term 'audio filter' can be applied to mean anything which changes the timbre, or harmonic content of an audio signal.

Self-oscillation

Self-oscillation occurs when the resonance or Q factor of the cutoff frequency of the filter is set high enough that the internal feedback causes the filter circuitry to become a sine tone sine wave oscillator.

See also

This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 



Copyright © World Library Foundation. All rights reserved. eBooks from World eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.