CD Quality & The Human Ear

[BigMoosie]

My music teacher several years ago stated that she could hear the information loss in CDs. She claimed that she could hear an improvement of quality in records over CDs. I have read about CD technology and remember finding that the sampling rate was well above our perception and the same went for bit-depth. Is this really possible or is she most likely just making this up?

 

Also, what is (roughly) the lowest bit-rate required for an mp3 before it becomes impossible to notice the compression? I can notice for 128 but not 160.

[Kedas]

A lot more information is lost/changed due to the music installation (including speakers)

BTW it's half the sample rate that has to be 'well above our perception'.

[swansont]

Is there a hearing equivalent to persistence of vision? It may be that the threshold for hearing digitization has a lot more variation for hearing as compared to sight.

[ecoli]

I don't know the standards for humans, but I do know that some people have a better ability to distinguish.

 

For example, my chorus teacher, last year, told me a story about this man he knew in college. He had perfect pitch to such a degree that he knew the exact pitch, (down to the cent, for those who know music theory) of any noise made... even a sneeze or something like that. However, unfortunately thisi person could not listen to music, especially live, because any note that was off even by the smallest fraction would irritate him. He simply couldn't listen to any music that wasn't perfect. Sucks, huh?

[YT2095]

My music teacher several years ago stated that she could hear the information loss in CDs. She claimed that she could hear an improvement of quality in records over CDs. I have read about CD technology and remember finding that the sampling rate was well above our perception and the same went for bit-depth. Is this really possible or is she most likely just making this up?

 

no she is NOT making it up, I rem having this exact same arg with someone about 10 year ago, even did a blindfold test to prove it, and I was right!

there IS a difference, although today I don`t notice it at all, the sample rate`s suposed to be 44Khz and play rate up to 22Khz.

the only thing I can explain this with is that back then when the CD was "new" the players weren`t quite up-to-snuff, and todays tech IS.

my main irritation was the "Whistle like" clipping effect it had, very high pitched sure, alot higher than some TV flyback oscs, but non the less it really got on my nerves.

you should ask her if she gets the same effect with modern CD players, the worst they can be accused of is often playing "modern" music (and that suck too mostly).

 

Gimme a Valve amp and an old 8 track, I`m happy

[danny8522003]

Couldn't this be due to the quality of the components rather than human perception? Although, different formats and equipment will obviously sound different.

[ecoli]

Gimme a Valve amp and an old 8 track, I`m happy

Give me a turn table and a 48 and I'm happy. I think there is a certain quality about record that gives that edge over 8-tracks, tapes and CDs.... plus you can actually SEE the cover art without a magnifying glass!

[bascule]

My music teacher several years ago stated that she could hear the information loss in CDs. She claimed that she could hear an improvement of quality in records over CDs. I have read about CD technology and remember finding that the sampling rate was well above our perception and the same went for bit-depth. Is this really possible or is she most likely just making this up?

 

The biggest way that CDs and records will sound different comes from the digital master. Digital masters of music done before the age of digital recording/production are always done from tape (as opposed to vinyl). This is unfortunate because tape degrades with time (whereas vinyl degrades with use). Furthermore, many of these songs are being mastered from copies of the original master, or copies of copies. Sometimes they'll be mastered from a copy which has been sitting around for 10 years of another copy which was 10 years old when the second copy was made. There are all sorts of fancy production techniques to try to regain the fidelity of the original master, but what you ultimately get is a distorted copy of the original master run through a bunch of filters to try to make it sound good.

 

If you have a copy of the vinyl which was cut around the same time that the song was recorded that hasn't been used excessively, chances are it will be much truer to the original master than the digital master you get on a CD, since vinyl doesn't degrade with time in the way tape does.

 

In terms of the format itself...

 

"Golden ears" listening testers can fairly reliably discern 16-bit from 24-bit sampling (this mainly affects the dynamic range, but also affects how well the Quadrature Amplitude Modulation produced by Digital to Analog Converters actually represents the shape of the original waveform. Postprocessing filters can help smooth out the blockiness that results from discrete sampling). With records sampling isn't an issue, because the way they store audio is continuous vs. the discrete sampling approach of CDs, however the dynamic range of records is about half that of CDs.

 

44.1kHz is the sampling rate. Because it takes at least two samples to represent a waveform, the highest frequency waveform a CD can store is 22050Hz. However, using only two samples to represent a waveform will sound quite awful. The Red Book (mastering standards for CDs) specifies that all audio must be run through a 20kHz lowpass filter first, so the maximum frequency a properly mastered CD can store is 20kHz, versus ~48kHz for a record. Frequencies above 20kHz cannot be heard. However that doesn't mean they are imperceptable; many of these frequencies resonate with various parts of the human body, so they are still tangible and therefore the "listening experience" as a whole is affected.

 

CDs have a dyanmic range of 90dB, whereas records have a dynamic range of 45dB. This is great for orchestral music which may express a large dynamic range spanning from pianissimo to fortissimo. However, most producers want to make the quieter parts of modern rock/pop music sound louder so they're easier for people to hear. This is a technique known as "compression." Typical rock music is compressed down to at LEAST a 45dB range (i.e. people LIKE the compressed sound of a record), if not lower. Many modern producers have a tendancy to overcompress music as this sounds trendy.

 

So really it all comes down to personal preference. Many people actually like the clicks and pops that vinyl produces. Some of us, however, try to keep our records clean. However, when you're talking about original recordings being done today in the age of digital music production, vinyl is more of a gimmick and will ALWAYS be lower fidelity than what you're getting on CD (after all, it's a perfect copy of what's in the engineer's computer), or sells to DJs who need to beatmatch the records and adjust their tempo (although CD players exist that let you do that too).

[ecoli]

The biggest way that CDs and records will sound different comes from the digital master. Digital masters of music done before the age of digital recording/production are always[/i'] done from tape (as opposed to vinyl). This is unfortunate because tape degrades with time (whereas vinyl degrades with use). Furthermore, many of these songs are being mastered from copies of the original master, or copies of copies. Sometimes they'll be mastered from a copy which has been sitting around for 10 years of another copy which was 10 years old when the second copy was made. There are all sorts of fancy production techniques to try to regain the fidelity of the original master, but what you ultimately get is a distorted copy of the original master run through a bunch of filters to try to make it sound good.

 

Right... so when older bands have been putting their stuff on CDs, they don't have the master tapes, so it's been a bitch getting the material to have good sound quality.

 

I beleive the've been having the same problems with older movies, IIRC. The master tapes are gone, so the quality is even less then what they originally were.

[swansont]

Give me a turn table and a 48 and I'm happy. I think there is a certain quality about record that gives that edge over 8-tracks, tapes and CDs.... plus you can actually SEE the cover art without a magnifying glass!

 

 

A 48?