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IEEE Membership & Staff
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| Milestone Buildings Exist
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No. New building has been built on the original site.
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| Milestone Distinguishing Features
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It is possible to transmit prediction coef … It is possible to transmit prediction coefficients directly. Quantizing predictive coefficients, however, needs many bits for maintaining the LPC spectral shape. It is also difficult to avoid the risk of instability of the coding system.
Partial auto correlation (PARCOR), invented by Dr. F. Itakura and Dr. S. Saito in 1972, enables an easy stability check but still needs many bits of quantization to maintain the LPC spectral shape. It is possible to reduce bit consumption for quantizing PARCOR by applying adaptive bit allocation and variable length coding schemes. Both schemes are, however, extremely sensitive to transmission channel errors.
LSP, an alternative representation technology for prediction coefficients, was invented by Dr. F. Itakura in 1975 [2]. It enables a simple stability check and can maintain the LPC spectrum shape with around 30% less bit consumption than PARCOR, even without using adaptive bit allocation or the variable length coding schemes [3] – [7]. This is because the quantization distortion of LSP has smaller and more natural influences on LPC spectral shape than PARCOR. Thus, small LPC spectral distortion is achieved by efficient coding of LSP in combination with prediction, interpolation, and vector quantization. n, interpolation, and vector quantization.
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| Milestone Obstacles Overcome
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Auto-regressive linear prediction coding ( … Auto-regressive linear prediction coding (LPC) technology is one of the most powerful and useful speech coding tools [1]. Pioneering investigations of the technology were independently and simultaneously started by Dr. B. S. Atal and Dr. M. R. Schroeder at AT&T Bell Labs in 1966, and by Dr. F. Itakura and Dr. S. Saito at NTT (Nippon Telegraph and Telephone) Labs. Representation and quantization of the prediction coefficients with less bit consumption and smaller LPC spectral distortion are the most critical issues in the LPC framework. At the same time, speech coding for cellular phones needs to be robust against transmission bit errors in the radio-wave environment. Thus, the representation method of predictive coefficients needs to achieve smaller LPC spectral distortion with fewer quantization bits while maintaining robustness against transmission channel errors. tness against transmission channel errors.
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| Milestone Plaque Mounting Details
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The plaque will be placed near the reception area in the ground floor entrance hall. All visitors have free access to this hall.
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| Milestone Present Site Owner
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NTT (Nippon Telegraph and Telephone) corporation
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| Milestone References
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[1] B. S. Atal, “The History of Linear Pre … [1] B. S. Atal, “The History of Linear Prediction”, IEEE SIGNAL PROCESSING MAGAZINE, pp. 154-157, MARCH 2006.
[2] F. Itakura, “Line Spectrum Representation of Linear Predictive Coefficients of Speech Signals,” J. Acoust. Soc. Am., 57, 533(A), 1975.
[3] JP Patent 56051116 - ALL POLE TYPE DIGITAL FILTER invented by F. Itakura
http://worldwide.espacenet.com/publicationDetails/biblio?DB=EPODOC&II=8&ND=6&adjacent=true&locale=en_EP&FT=D&date=19810508&CC=JP&NR=56051116A&KC=A
[4] US Patent 4,393,272 Sound synthesizer invented by F. Itakura and N. Sugamura
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=4,393,272.PN.&OS=PN/4,393,272&RS=PN/4,393,272
[5] F. Itakura, “Statistical Methods for Speech Analysis and Synthesis –from ML Vocoder to LSP through PARCOR –,” IEICE Fundamental Review Vol.3 No.3. 2010. (in Japanese)
Abstract: The invention process of the line spectrum air (LSP), one of the most important analysis technologies for speech signals, is described. Partial auto correlation (PARCOR) and LSP are alternative representation methods for a speech spectrum shape or a vocal tract shape. Both methods were invented at NTT Labs in 1972 and 1975, respectively. This paper covers the processes for these inventions, starting from the original invention of a speech analysis method based on maximum likelihood estimation in 1966.
[6] F. Itakura, T. Kobayashi and M. Honda, “A Hardware implementation of a new narrow and medium band speech coding,”, Proc. ICASSP 82, pp. 1964 – 1967, 1982.
[7] F. Soong and B. H. Juan, “Line spectrum pair (LSP) and speech data compression,” Proc. ICASSP 84, Vol. 9, pp. 37 – 40, 1984. roc. ICASSP 84, Vol. 9, pp. 37 – 40, 1984.
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| Milestone Site Access Details
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NTT’s receptionists are always near the plaque, and the plaque will be displayed in a transparent hard case.
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| Milestone Site Description
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Initial invention, follow up investigations and developments have been carried out at this site.
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| Milestone Site Owner Approval
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Yes +
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| Milestone Supporting Materials
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[8] ITU-T G.723.1(Dual rate speech coder f … [8] ITU-T G.723.1(Dual rate speech coder for multimedia communications transmitting at 5.3 and 6.3 kbit/s)
http://www.itu.int/rec/T-REC-G.723.1-200605-I,section 2.4-2.7
[9] ITU-T G.729(Coding of speech at 8 kbit/s using conjugate structure algebraic-code-excited linear prediction (CS-ACELP))
http://www.itu.int/rec/T-REC-G.729-200701-S, section 3.2
[10] 3GPP AMRhttp://www.etsi.org/deliver/etsi_ts/126000_126099/126090/10.01.00_60/ts_126090v100100p.pdf, section 5.2
[11] 3GPP2 EVRC
http://www.3gpp2.org/public_html/specs/C.S0014-0_v1.0_revised.pdf, section 4.2
[12] IETF SILKhttp://tools.ietf.org/html/draft-vos-silk-01, page 261
[13] Example of VoIP gateway supporting G. 729
http://www.cisco.com/en/US/docs/ios/solutions_docs/voip_solutions/CAC.html ios/solutions_docs/voip_solutions/CAC.html
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| Milestone proposal submitted
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true +
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| Proposed Milestone IEEE Section
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IEEE Tokyo Section, Japan +
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| Proposed Milestone Location
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NTT Musashino R&D center
9-11, Midori-cho 3-Chome Musashino-Shi, Tokyo 180-8585 Japan
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| Proposed Milestone Name
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Line spectrum pair (LSP) for high-compression speech coding, 1975 +
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| Proposed Milestone Plaque Citation
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Line Spectrum Pair, invented at NTT in 197 … Line Spectrum Pair, invented at NTT in 1975, is an important technology for speech coding. A speech synthesizer LSI was designed based on LSP in 1980, and many international speech coding standards of ITU-T (IP phones), 3GPP, 3GPP2 (3rd generation cellular phones), and the Internet Engineering Task Force have adopted LSP as an essential technology. These standards cover almost all cellular and IP phones worldwide. most all cellular and IP phones worldwide.
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| Proposed Milestone Year
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1975 +
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| Modification dateThis property is a special property in this wiki.
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14 March 2013 13:26:55 +
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