[BC] RAIN report: HD Radio s Creative Thinking

Sat Oct 15 10:52:58 CDT 2005

XM and Sisius are both using bitrates far lower than 96 KBPS, thus 
causing the artifacts to become very noticable.

At the full 96 kbps, the artifacts require some concentration to hear.

The AM HD system artifacts (32kbps), on the other hand, *does* sound 
very irritating to me at times.   I find that I am of the group that is 
VERY sensitive to low bitrate SBR artifacts, and when in a room of, say, 
10 people, I am usually one of three or so who hear it. Everyone else is 
blissfully unaware of the "digital aliasing-like" artifacts that drives 
me and the other few insane.

AACPlus and MP3Pro (both use the SBR coding) both exhibit similar 
results for me at bitrates lower than 48kbps.

 From what I hear the satellite folks are hovering between 64 and 32 
kBPS per channel....typically closer to 32kbps...

-Cornelius

DANA PUOPOLO wrote:
> AAC plus is one of he better ones. Indeed, I listen to it every day (via XM).
> That said, I still hear artifacts all the time. So does my wife.  I'm a 51
> year old man who's HF hearing I'm sure has declined over the years. Younger
> men (and women) likely hear them even worse.
> Unless I actually READ the tests (and their results), I assume notning about
> them. By the way, I can pick out BR reduced audio that's under 256K  when
> compared with the original source with near 100% accuracy using headphones I
> know (Grados).
> I recall reading years ago that Bell Labs (at least I think it was them) was
> trying to determine the optimum bandwioth to use for sound reproduction (this
> was in the 1930's). They set uo a "high quality)"  (for the time) audio system
> and ran essentially double blind tests of different audio bandwidths. They
> were surprised to find that people overwhelmingly preferred narrow bandwiths!
> This ran contrary to what they thought people would like.
> 
> Finally they realized why: The audio reproduction equipment was flawed, even
> though it was the best available. So, they built a stage with an orchestra.
> The orchestra sat behind an acoustically transparent curtain.Between the
> orchestra and the curtain was a set of louvers that could be opened or closed
> without the audience knowing which position they were in. When closed, the
> louvers attenuated all highs over 5 kHz.
> NOW they discovered the audience overwhelmingly preferred the full audio
> bandwith over the narrow band audio. Had these scientists not been the
> visionalies we now know them to be, we might have been STUCK with inferior
> reproduced audio for generations.
> 
> Quite frankly, FM stations could make 'near digital' sound tomorrow by turning
> down their audio processing a few notches. The fact that they do  not want to
> will ultimately kill them!  Listeners have choices now that simply didn't
> exist  years ago, and they are goig to these alternatives in bunches. HD radio
> will not change this. Besides, how many stations take theiHD channel and put
> audio on it with a 5 db dynamic range? The majority, I'll wager. Why HAVE a
> near High Fi medium if you're going to trash it out of the box?  Remember, no
> listener can undo the changes  (damage?)  caused by audio processing. Analog
> FM has a 50 db dynamic range, give or take. 40 db of this is wasted by the
> average FM station.
> HD radio has an 80 db dynamic range.  70 db of this is wasted by the average
> HD station.  Why bother with HD if you're going to trash it so?
> 
> I'm not hardly going to visit the dueling codec arguement now; that's a whole
> topic upon itself. Let's just say that I'm sure the coding used by Starguide 
> duels with HD's coding to some degree (unless they happen to be identical).
> Let's also say that the MP2, MP3 and/or WMA coding used by the various HD
> based audio storage systems  every station uses these days also duels with HD
> (I know that CC uses MP2 with Prophet) does as well.
> 
> -D
> 
> ------ Original Message ------
> Received: Sat, 15 Oct 2005 02:21:28 AM PDT
> From: Robert Orban <rorban at earthlink.net>
> To: broadcast at radiolists.net
> Subject: Re: [BC] RAIN report: HD Radio s Creative Thinking
> 
> At 09:18 PM 10/14/2005, you wrote:
> 
>>From: DANA PUOPOLO <dpuopolo at usa.net>
>>Subject: Re: [BC] RAIN report: HD Radio s Creative Thinking
>>To: Broadcast Radio Mailing List <broadcast at radiolists.net>
>>Message-ID: <041JJoej66912S09.1129350957 at cmsweb09.cms.usa.net>
>>Content-Type: text/plain; charset=ISO-8859-1
>>
>>I have heard AAC plus, and even at 96K can clearly hear its artifacts.
>>I would wager that most women can (clearly) hear them too. But after all,
>>women only represent 55-60% of the audience, so why do they matter?
>>When you remove 95+ % of anything, it's not going to sound nearly as good as
>>the original.
>>
>>So my comparison IS valid!
> 
> 
> While you are of course entitled to your preference, you seem to be 
> unusually sensitive to SBR's artifacts, at least according to the 
> double-blind listening tests made by Coding Technologies, not to mention 
> 3GPP2 (3rd Generation Partnership Project 2), ISMA (Internet Streaming 
> Media Alliance), DVB (Digital Video Broadcasting), the DVD Forum, Digital 
> Radio Mondiale, and 3GPP (3rd Generation Partnership Project), all of which 
> have standardized on aacPlusV1 or aacPlusV2 and/or accepted the aacPlus 
> codec as part of their system specifications. I am suspect all of the 
> listening panels included women, as these are all serious organizations and 
> did not make their choices frivolously.
> 
> Bob Orban 
> 
> 
> 
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-- 

- Cornelius Gould
________________________________
"The significant problems we face cannot be solved at the same level of
thinking we were at when we created them."
- Albert Einstein (1879-1955)