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System and method for modifying speech signals

A voice signal and signal technology, applied in the processing of voice signals, a system for processing a voice signal, and enhancing the narrowband voice signal field at the receiver, which can solve problems such as high-frequency distortion and metallic voice

Inactive Publication Date: 2003-02-12
TELEFON AB LM ERICSSON (PUBL)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

One disadvantage associated with telegraph codebooks is that they require significant training
These methods are simple and effective, but they often introduce high-frequency distortion that makes the voice metallic

Method used

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  • System and method for modifying speech signals
  • System and method for modifying speech signals
  • System and method for modifying speech signals

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Embodiment Construction

[0032] best practice

[0033] The present invention provides improvements to speech signal processing that can be implemented at a receiver. According to one aspect of the invention, the frequencies of the speech signal in the higher frequency region are synthesized using information in the lower frequency region of the received speech signal. The invention makes advantageous use of the fact that speech signals have harmonic content that can be extrapolated into higher frequency regions.

[0034] The present invention can be used in conventional wireline (ie fixed) telephone systems or in wireless (ie mobile) telephone systems. Since most existing wireless telephone systems are digital, the present invention can be easily implemented in a mobile communication terminal (eg, a mobile phone or other communication device). figure 1 A schematic depiction of functions performed by a communication terminal acting as a receiver according to various aspects of the present invention i...

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Abstract

A system and method for speech signal enhancement upsamples a narrowband speech signal at a receiver to generate a wideband speech signal. The lower frequency range of the wideband speech signal is reproduced using the received narrowband speech signal. The received narrowband speech signal is analyzed to determine its formants and pitch information. The upper frequency range of the wideband speech signal is synthesized using information derived from the received narrowband speech signal.

Description

Background of the invention [0001] The present invention relates to techniques for transmitting speech information in communication networks, and more particularly to techniques for enhancing narrowband speech signals at a receiver. [0002] In the transmission of speech signals, there is a trade-off between network capacity (ie, the number of calls being transmitted) and the quality of the speech signals for those calls. Most telephone systems in use today encode and transmit speech signals in a narrow frequency band between approximately 300 Hz and 3.4 kHz according to Nyquist's theorem at a sampling rate of 8 kHz. Since human speech contains frequencies between approximately 50Hz and 13kHz, sampling human speech at an 8kHz rate and transmitting a narrow frequency range of approximately 300Hz to 3.4kHz must ignore information in the speech signal. Therefore, the telephone system necessarily degrades the quality of the speech signal. [0003] Various methods of extending th...

Claims

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Application Information

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IPC IPC(8): G10L21/02
CPCG10L21/038
Inventor U·林格伦H·古斯塔夫松P·多伊特根C·图尔班
Owner TELEFON AB LM ERICSSON (PUBL)
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