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 the wider band signal from extracted lower-band features. Others encode the high band using very few bits. This is often sufficient since the ear is less sensitive to distortions in the high band compared to the low band.

Read more about Bandwidth ExtensionBass Enhancement of Small Loudspeakers, Bandwidth Extension of Speech in Telephone Systems, Bandwidth Extension of Audio

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Famous quotes containing the word extension:

    The motive of science was the extension of man, on all sides, into Nature, till his hands should touch the stars, his eyes see through the earth, his ears understand the language of beast and bird, and the sense of the wind; and, through his sympathy, heaven and earth should talk with him. But that is not our science.
    Ralph Waldo Emerson (1803–1882)