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[hts-users:03336] Re: [hts-users:03334] RE: [hts-users:03326] Re: [hts-users:03323] Questions of the untied stage in the sd training.pl?


Hi, ArthurLeo,

   It is stated in HTK book that "The philosophy of system
construction in HTK is that HMMs should be refined incrementally." It
is also true in HTS.
   For the first time of clustering, we get full context HMMs which is
simply cloned from mono phone and re-estimate for just once, so the
precision of initial full context HMMs is generally acceptable but not
very high. When you cluster these initial full context HMMs, the
robustness of HMMs is much improved and thus could be re-estimated for
$nIte times rather than just once. When we untie and re-estimate these
clustered full context HMMs, we get higher precision of these untied
full context HMMs in principle. Then the second clustering operation
is needed to cluster these untied full context HMMs which is refined
compared with the cloned and re-estimated intial full context HMMs.
   In summary, the cluster-untie-recluster operation sequence is
better than clustering only once to get higher precision and
robustness of HMMs in principle.

   I did not try to cluster-untie-recluster-reuntie-recluster2, as I
guess its improvement will not be worthy when considering its
increased training time.

YangWang


2012/6/6 ArthurLeo <bin007.zhao@xxxxxxxxxxx>:
> thank you for your reply!but I still have the question  why doing  further
> untie, re-estimate, recluster and herest
> HMMs  can get the better re-estimation accuracy? Have the inevitable reasons
> in theory? or can you explain  in theory simply?
>> Date: Wed, 6 Jun 2012 09:31:50 +0800
>> From: yangwang84@xxxxxxxxx
>> Subject: [hts-users:03326] Re: [hts-users:03323] Questions of the untied
>> stage in the sd training.pl?
>> To: hts-users@xxxxxxxxxxxxxxx
>
>>
>> Hi, ArthurLeo,
>>
>> You asked about "{cluster, herest}, {untie, herest}, {recluster,
>> herest}". When we further untie, re-estimate, recluster and herest
>> HMMs, we usually get better re-estimation accuracy than just cluster,
>> herest. You may verify that the corresponding HMM definition files are
>> a little different. Through my informal listening test, I found the
>> synthesi zed speech is indeed a little better.
>
>>
>> YangWang
>>
>>
>> 2012/6/5 ArthurLeo <bin007.zhao@xxxxxxxxxxx>:
>> > Hi all,
>> > When I read the SD training.pl(hts2.2 version),I found that there is a
>> > untied stage, I want to know why do this stage? why not use the before
>> > stage
>> > result cluster.mmf(after the herest) as the final model? why do the
>> > untied
>> > stage then clustered, next using herest result as the final model? what
>> > is
>> > the function of
>> > adding the untied stage? what is the benefit? Can someone give me an
>> > answer? Thank you in advance!
>>

Follow-Ups
[hts-users:03337] RE: [hts-users:03336] Re: [hts-users:03334] RE: [hts-users:03326] Re: [hts-users:03323] Questions of the untied stage in the sd training.pl?, ArthurLeo
References
[hts-users:03323] Questions of the untied stage in the sd training.pl?, ArthurLeo
[hts-users:03326] Re: [hts-users:03323] Questions of the untied stage in the sd training.pl?, 王洋
[hts-users:03334] RE: [hts-users:03326] Re: [hts-users:03323] Questions of the untied stage in the sd training.pl?, ArthurLeo