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Re: Articulation Index

Agreed that for very low bit rate, especially when robotization occurs,
quality and intelligibility are different. For the commercially used codecs
like GSM FR/EFR/HR/AMR, IS54/96, ITU G.723.1/727/728/729 I think it will
work. We have a formal listening test that used speech listening effort
subjective testing that shows P.862 PESQ can be used for intelligibility
within limits.

In general the STI cannot be used to assess intelligibility of speech
degraded by low bit rate codecs.

John Beerends

-----Original Message-----
From: D. Sen [mailto:dsen@ieee.org]
Sent: vrijdag 16 augustus 2002 16:44
To: J.G.Beerends@KPN.COM
Subject: Re: Articulation Index

John G. Beerends wrote:
> If you want to measure speech intelligibility of coded speech
> (distortion+noise) the AI can definitely not be applied. An option is to
> ITU-T recommendation P.862 that describes a method called Perceptual
> Evaluation of Speech Quality
> .862.
> The method was developed for speech quality but in general speech quality
> and intelligibilty are closely linked

There are many instances where speech intelligibility and quality are
not correlated. The LPC-10e (US Federal Standard - 1015) algorithm is an
example where intelligibility is high but quality is atrocious.

The Speech Transmission Index (Steeneen, H.J.M and Houtgast, T., "A
physical method for measuring speech-transmission quality", JASA, 67(1),
1980) might be a better objective measure of intelligibility than the AI
for systems with nonlinear distortion.

> and the algorithm can be re-optimized
> for intelligibility. A paper describing the method will be published
> (probably this year) in the J. Audio Eng. Soc.
> John Beerends
> KPN Research
> -----Original Message-----
> From: Brent Edwards [mailto:brent@edwards.net]
> Sent: donderdag 15 augustus 2002 0:51
> Subject: Re: Articulation Index
> If the coder is only introducing stationary additive noise to the speech,
> then you can do this. If the perceptual coder is affecting the speech in a
> way different from this (which I suspect it is), then you cannot apply the
> AI (to my understanding of the Speech Intelligibility Index ANSI
> --Brent
> ----- Original Message -----
> From: "Hugo de Paula" <hugodepaula@GMX.NET>
> Sent: Wednesday, August 14, 2002 12:56 PM
> Subject: Articulation Index
>>The Articulation Index gives a measure of the intelligibility of hearing
>>speech in a given noise environment. I have some recordings that I used
> some
>>perceptual coding techniques that caused distortion to these signals. I
>>would like to calculate the AI of  the distorced sound. As the AI is
>>calculated based on the environmental noise, I would use the reference
> sound
>>to measure the 'noise' in the distorted sound.
>>>Hi Hugo,
>>>Pardon, I can not help you, but I would like to know what means
>>>"articulation index" for a pair of sounds.
>>>What is the use of this figure?
>>>Hugo de Paula wrote:
>>>>Hi all,
>>>>Does anybody know of a matlab code for calculating the Articulation
>>>>given a pair of sound files: the first with the original recorded
> source
>>>>the other the live recording?
>>>>thank you,

D. Sen, PhD