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*To*: AUDITORY@xxxxxxxxxxxxxxx*Subject*: Re: Pole-zero estimation from complex cepstrum*From*: Eckard Blumschein <Eckard.Blumschein@xxxxxxxxxxxxxxxxxxxxxxxxxx>*Date*: Mon, 15 May 2006 08:08:54 +0200*Comments*: To: Tarun Pruthi <tpruthi@GLUE.UMD.EDU>*Delivery-date*: Mon May 15 02:32:32 2006*In-reply-to*: <Pine.GSO.4.63.0605121556480.8068@y.glue.umd.edu>*References*: <Pine.GSO.4.63.0605121117450.8068@y.glue.umd.edu> <4464B48A.6020904@uiuc.edu> <Pine.GSO.4.63.0605121556480.8068@y.glue.umd.edu>*Reply-to*: blumschein@xxxxxxxxxxxxxxxxxxxxxxxxxx*Sender*: AUDITORY Research in Auditory Perception <AUDITORY@xxxxxxxxxxxxxxx>*User-agent*: Internet Messaging Program (IMP) 3.2.6

> > Tarun Pruthi wrote: > >> I am working on the automatic detection of vowel nasalization using > >> knowledge-based acoustical parameters as part of my PhD thesis work. ... > >> One of the techniuqes that I only got a short description about seemed to > >> be very different. This was based on the complex cepstrum. While Oppenheim and Schafer did not even consider the possibility that real-valued analysis of a single signal is absolutely equivalent to the complex-valued one except for an arbitrarily chosen point of reference, I am not aware of any reason for choosing complex cepstrum instead of real cepstrum. As far as I know, just the real cepstrum has proven successful in practice for decades. Complex-valued spectrum in general has a lot of disadvantages. Above mentioned reference merely relates to the arbitrarily choosen reference of time fixed at midnight in Greenwich. Auditory function does not rely on this event-related time scale. The auditory system does not know linear phase. Consequently complex spectrum twice includes redundancy giving rise to ambiguity, confusion and non-causal as well as possibly unstable behavior. As long as one considers time extending from minus oo to plus oo, this redundancy must not be omitted. However, if one considers elapsed time an always only positive quantity, the volume of data reduces to just a quarter, and spectrum simplifies without any loss of information. Most physicists merely hesitate to abandon their unjustified believe in pre-existing future time. Regards, Eckard

**References**:**Pole-zero estimation from complex cepstrum***From:*Tarun Pruthi

**Re: Pole-zero estimation from complex cepstrum***From:*Tarun Pruthi

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