In a recent BBC report on the web, it said Microsoft were launching a rival to the itunes software from Apple. Microsoft Music will do the same job, be be higher quality - 160k, whereas the Apple itunes is 128k.

If these numbers work the same for mp3 and DAB, then the line of thought is that both are below CD quality. In the DAB topics most people say 128k, and even 160k is far lower than that of CD.

I knew MP3 lowered the quality, but I had no idea it was by that much!

Dave

Well CD quality is about 1,200kbps wav

so a 128kbps mp3 is about 1/10th the size. but it isn't 1/10th the quality, which is the point really.

I'd challenge anyone to tell the difference between a 156kbps mp3 and a cd.

i rip at 192 and to me it's perfect.

I would like some info from people with hifi seps, like NAD, Dennon, with "hard wired" CD/SACD/DVD players, and see if they can hear the difference. I am just thinking about all the times audio quality (or lack of it) on DAB gets gets talked about.

Dave

I can easily tell a 128kbp mp3 through my Cambridge audio seperate system. It is most noticable on the hi-hats in music which start to sound less metallic and more erm, wooshy. Havent really tried proper listening tests with higher rates than that though.

Out of interest, what bit rate are Minidiscs (using normal ATRAC compression)?

Apparantly - most people can't tell the difference when you get above 192kbps.
160kbps is good enough for quite a few people.

Audio enthusiasts, with a better trained ear can hear the difference up to about 256kbps - but above that, the quality-loss is so slight that the human ear is apparantly incapable of distinguishing it.

Quite a few people have said the 192kbps is more or less the minmum needed to "trick" most people into thinking they are hearing a CD.

I guess the quality of the mp3 "equipment" also plays a part. I have seen quite a bit wrote about the low quality of the regular headphones you get with the Apple ipod. I suppose the reproduction/amplification of the device (portable or otherwise) also plays just as big a part as the kbps level of the material. So one one system, 128kbps may sound ok, but on another it might sound much worse.

How much better than a pre-recorded audio tape is mp3 (128kbps)?

Dave

I can easily tell a 128kbp mp3 through my Cambridge audio seperate system. It is most noticable on the hi-hats in music which start to sound less metallic and more erm, wooshy. Havent really tried proper listening tests with higher rates than that though.

Out of interest, what bit rate are Minidiscs (using normal ATRAC compression)?
[quote]

Yes, I can tell the differance between a bought from the shop CD and a set of MP3s at 128K or 192, 128 -def (DJ Shadow sounds quite "distant" ) and Jack Johnson sounds quite "watery" at 192K, through the Missions - The better the speakers, the more detail you are going to notice.

Alex

It is important to note that a 128k MP3 and 128k DAB are not the same thing. DAB digital radio broadcasts using MP2 not MP3. As you would guess MP3 being the newer and more advanced standard is a fair bit more efficient and can produce better sound quality at the same bit rate (e.g. 128k)

Of course newer formats like WMA are even more efficient and can actually reach CD quality at just 128k where as most people agree 192k is needed for CD quality in MP3.

I ensure that any MP3s i rip myself are 192k at this rate i cannot distinguish at all from a CD and i do have a pretty decent 7.1 speaker set up on the PC. I don't see any point in going higher than this as i cannot percieve any quality advantage at all.

I'd happily take your challenge.

Nothing less than 320kbps will do for me.

I do a lot of listening on top-line Sennheisers and even 320kbps can be noticeable, especially with acoustic, natural instruments (ie. piano) in the higher registers.

mp3 is the 'poor man's' hi-fi. The quality is woeful compared to CD or vinyl. When you compare it to 'newer' formats like SACD and DVD-A it is positively stone age.

It is, of course, useful for storing the odd downloaded track, but would NEVER back up my entire precious vinyl & CD collection at Mp3 compression on hd or cd.

Go and visit your local proper hi-fi store, and LISTEN to a really good system - you will never go back!

BTW - good hifi is capable of reproducing nuances not obviously present in the original recording - however, they make the music more real, and even give information to the hi-fi to give a good soundstage. A high quality recording in stereo will not just have left-right-middle channel info, but up/down and depth as well - it will give surround sound systems a good run for their money!

Very true!

But MP3 means 'MPEG 1 layer 3' - ergo, it is derived from the first generation of MPEG. No?

MDs at standard rate use around 292kbps. LP2 and LP4 take the rates down to around 132kbps and 66kbps, IIRC. Most of the time, LP4 sounded fine to me.

I don't know about the bit rates offered by Hi-MD, I now use an iPod more than MD, for which I use 128kbps AAC and am happy with the sound quality that gives.

You can't beat the original CD. Yet, a decently done recorded CD as 192K mp3s are adequate enough and sound Cd Quality. But, yes I can still tell the differance, and the volume is quite a bit lower than the original.

Alex

The reason that 128kps is not 1/10th the quality of 1.2Mps is it works
logarithmically .
For the same reason that a 300W output amplifier is not ten times louder than a 30W one.
However, that large difference in bit-rates still makes a big difference to the listening experience, something which is always difficult to quantify in pure numbers.

Have you tried listening to a 128kbps .wav file? the reason that it is not 1/10th the quality is that it's compressed.

With regard to 'loudness,' this is highy subjective. And i'm not certain that you have a difinitive answer any more than i do.

Just because the -dB used to measure loudness is logarithmic doesn't mean that loudness itself is.

What is loudest....

100dB @ 25kHz or
90dB @ 15kHz

???????

I've always found mp3's I've downloaded off the internet are badly encoded as you can hear the compression artifacts even on a 192kbps mp3 and also they are too loud!

All of my mp3's are encoded at 256/320 vbr peaking at -3dB. Good enough for me, but as has been said earlier, nothing beats the original CD quality uncompressed wave file!

I have lots of reasonable mp3 and wma files on my computer, but I rarely hear any defects because my sound card is so bad (I have a good pair of headphones).

I still play CDs on my budget Kenwood>Arcam>MS10i separates system, but that equipment is capable of resolving the difference between mp3/wma/aac/etc. and CDs. My computer isn't.

It's horses for courses really - mp3 etc. has revolutionised portable music, but it is insufficient for 'serious' listening. I just hope that uncompressed music will still be available in the future...

The answer to your question is, either or neither is louder than the other! In fact the question itself is meaningless without more information.

Decibels are a RATIO between two values not an absolute measurement of some quantity. Therefore is is meaningless to say some noise is 100dB without also giving a baseline reference for what you are describing.

So in your question above if the baseline for the 100dB @ 25kHz is more than 10dB LOWER than that for the 90dB @ 15kHz then the 25kHz tone will be the same or lower in loudness than the 15kHz tone (not that most people would even be able to hear a 25kHz tone anyway!! )

And you also have to factor in the non-liearity of the ear with both frequency and sound pressure level so depending on what frequency you test at and at what sound pressure level you can get all kinds of variations in perceived loudness.

The subjective loudness of some noise has been well researched over many decades. Basically an increase of 10dB is required to give a doubling of perceived loudness. Thus a 300W amp is only twice as loud as a 30W amp and a 3000W amp will be needed to double the lodness once more!

Yeh... I think mp3 downloading is aimed more as music for the masses, rather than your 2k's worth of audio kit enthusiast... I personally listen to music in the office on a 120 quid stereo, and in the car mostly, so 128 is fine for me.

It'd be nice if download services could offer better than 160 or 128, but I suppose it's a matter of cost (i.e. extra server space) for them.

Yes i know this, that was the point i was making. ie i was saying that tinminer comparig bit rates to loudness was just not making any sense.

There are a couple of lossless formats around if anyone is being really fussy.

windows media audio lossless is VBR between 470 & 940 kbps

I wasn't directly comparing loudness to bit rates. The point I was trying to make is that, like audio power outputs, bit rates are logarithmic, i.e. a 128kps needs to be 10 times faster to improve audio quality. Going from 128 to 256kps, while audible, doesn't increase the sound quality that much. Also the codecs used in wmv. and mp3. are audible when played through a decent hi-fi, but generallly not audible when played through a PC.

WMA at 960kbs approaches CD quality, but isn't much used by the likes of napster - yet!

As I have a pretty good Hi-Fi, downloading tracks off the internet is pretty much useless for me. It takes all the enjoyment out of the listening experience.

That format is LOSSLESS, like the zip format. it is exactly the same as uncompressed.

Now i like the MP3 format, but some of you might be interested in looking at the Vorbis codec. the quality is better than MP3.

have a quick google.

i think mp3 is only used due to it being popular, and not for its (lack) of quality.

Hence the popularity of the Apple ipod.

Dave