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Thank you for your comments. I would like to add some explanations on LSP and the standardization process. LSP is the name of a signal processing technology invented at NTT; it is not a brand name. For the Japanese cellular phone system (PDC: Public Digital Cellular) standardized in 1993, LSP, as well as other essential technologies invented at NTT, has been licensed to all organizations (service providers, chip and system manufacturers) for free. For all other internal standardizations on speech and audio coding, NTT has licensed the essential technologies to all with reasonable and nondiscriminatory conditions. For speech and audio compression technologies, standardization of specifications is essential to ensure interoperability among many users and operators. For most of the international standards of speech and audio coding methods for cellular and IP phones created at ITU-T, 3GPP, and 3GPP2, the specifications were decided by a process of serious technical competitions or technical evaluations based on subjective listening tests. On the basis of the results, it was found that the selected scheme, either proposed by NTT or by other organizations, should use LSP technology as a representation tool of spectrum, because performance was degraded without it. The technical merits of LSP have been proven by numerous speech coding experts throughout the world.
I may admit that “contributed to the realization of digital speech communication over mobile channels and the..” may be replaced with “contributed to the enhancement of digital speech communications over mobile channels and the..” We appreciate your comments and advice.