Noise reduction

January 18, 2023
 by Paul McGowan

Remember back in the day when Dolby noise reduction was the thing?

I remember thinking to myself; this is nothing short of magic. Kind of like the RIAA. Boost the heck out of the high frequencies and then run them through a low pass filter to make everything right again. In the process, hiss is lowered.

Magic.

What’s worth noting about this is that today there’s no such need for noise reduction processing because there is no noise to eliminate.

This brings us to the idea of how the future works: Band-Aids->lead to a higher bar->that leads to a whole new technology.

We didn’t come up with a fancier noise reduction algorithm than did Ray Dolby. No, we just got rid of the problem altogether. With newer digital technology, noise levels are beyond the threshold of human hearing.

If you think about it, the process of Band-Aid->leading to higher expectations->leading to new technology has been happening for some time now: We eliminated the need for woofer whizzer cones by inventing the tweeter. We obviated the need for dynamic range expanders by moving to digital audio. We side stepped the problems of tape noise, rolled-off highs, and lossy duplication by chucking the process of tape recording entirely.

And that’s kind of the thing isn’t it? At first there’s a clever Band-Aid that works well, shows us the way forward, and sets our dreams for the future.

And then we rip the Band-Aid off and accept the new technology.

I wonder what’s next to come?

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29 comments on “Noise reduction”

  1. I don’t agree. A lot of vintage music was recorded on tape and those same master tapes hiss and all were used to make CDs. The signal to noise ratio and dynamic range of those recordings cannot be improved over the original master tape simply because it was transfered to a CD or DSD. You would only get close to zero noise if the recording was done in pure DDD.

    1. I read an interesting explanation about why 24/96 PCM has become the most prevalent capture format, giving superb sound quality even when the final product is a 16/44 PCM file or CD. Simply put, the extra bandwidth and dynamic range of 24/96 means that it is really not difficult to avoid low level noise and at the other end, clipping. In the early days of digital recording when the capture used 16/44 PCM, it was much harder to keep the entire recording within the constraints of 16 bit files.

      I’m not a great fan of historic recordings, but I’ve listened several times on Qobuz to a live recording at Wigmore Hall by Shura Cherkassky. This was done in the early 1990s and it is scary how well the recording captures the acoustic of a room I know very well. It is a 16/44 file, probably captured in that as well.

      1. It has really helped, even “amateur” recordists like me who record live concerts in various venues from bars to large coliseums. Back in the old days of using cassettes we had to be very careful to not oversaturate the tape, sometimes “riding the gain” or when 16-bit/44.1KHz DAT came along we had to be careful of clipping on loud sounds. But today, even a modest $250 digital recorder can record at 24-bit/48KHz or even 24-bit/96KHz if you don’t care about file size being larger. Having those extra bits means I can set a recording level around -12dB and just let it run, very rarely having to worry about clipping or the noise floor. Makes life a little easier.

    2. Not true. An obvious example is where Bob Ludwig managed to reduce the tape hiss that was very apparent in Dire Straits – ‘Love Over Gold’ by 85%.
      Listen to the original (unremastered) release & then listen to
      the Bob Ludwig remaster.

  2. Terrific post, Paul.

    Definitely had me thinking….man…what could be next?

    It is amazing to think about and how far we’ve come with the evolution of audio playback.

    And like Martin (fat rat) said “long live CDs !” 🙂

    God. I’ve got tons of them and they sound great! Gonna be hard to beat. 🙂

  3. My main hifi units do not follow this Band Aid theory. Devialet was created by a telecoms technology expert and a product designer who applied microtechnology and unique design to create a totally new product with an incredibly low noise floor and extreme dynamics. They went to the Munich show in 2010, signed up a global network of distributors and never looked back. Their manufacturing and distribution model was equally unique, giving them a massive cost advantage. The rest of the house has another unique product by a company set up by a speaker designer and product designer who together go back as far as creating the B&W Nautilus in the 1980s, which is still in production. They designed a complete hifi qualify wireless streaming and speaker system that includes lighting that is the size of a jam jar and costs under $500.

    In both cases they had a clear idea of the product concept, and they had to design a lot of new technology to achieve it. No Band Aids were used.

    The CD player was a completely new technology that eliminated the noise problem overnight, no Band Aid, developed by Sony and Philips. Class D amplifiers from Phillips eliminated the noise and heat problem overnight, and now hundreds of brands just drop them in as OEM components.

    A lot of product tweaking goes on leading to update products, but rarely does it make the previous product redundant. New technology that actually changed anything seems to be extraordinarily rare. I wonder what will be next.

  4. When a new technology is introduced to solve a problem it also introduces a whole set of new problems to be resolved which are discovered over time. Look at the development of digital audio over the years.
    Electric cars, solving a problem? I hope so but we’ll see.

    1. The first CD players had quite high jitter (audible?), but were significantly improved within 5 years to the point that it then made no difference to most. When streaming started about 20 years ago we used AAC or mp3 from an iPod and for the vast majority of people not much has changed, as wireless bluetooth prevails and the quality is much the same.

      The problems exist, if not are created, almost exclusively for audiophiles, whose life blood is something needing fixing, and if there isn’t a problem they will create one. Everyone else is as happy as Larry without a care in the world about sound quality.

  5. Blood Orange – New album May 5th, by Freya Ridings – available in cassette form! (Obviously we need to ask what type basic tapes; advanced fine-grained, or microferric, tapes; and high-grade ferricobalt tapes.) It’s enough to send Paul completely digital.
    I feel I’ve slipped into a wormhole……. Now where’s my old Awia?

  6. Perhaps a little too Star Trek for now, but in the future I could see a device that could be implanted to directly stimulate the auditory nerves, bypassing the ears completely such that those who are even deaf might hear again, and not only hear, but hear well with no high frequency roll off as they age and no tinnitus. By then there may be a “Bluetooth” codec that could even do DSD512. Such devices might hurt speaker sales though…ha!

  7. The crazy thing is that sometimes the lack of a little tape hiss or noise floor makes music sound artificial in a way, similar to recordings of concerts through a soundboard without any room sounds or reflections. They sound good, but they don’t sound real, they seem not as open and airy.

  8. Um, are cds not the 80s bandaid?
    “I’ll take the hi-res version for a thousand please Alex”
    “I am stuck on cd, cause cds stuck on me” 😉

    It’s hard to get thru the day without a childhood tv commercial tune.
    Or a Schoolhouse Rock song.
    Lolly lolly lolly get your adverbs here…

    I have several albums I bought in vinyl, audiophile vinyl, direct to disc Japanese vinyl, cd & then digital hi-res. Do the previous versions ever get played? Nope. Regrets? None. And I’ll buy it again in the next version. But I still need to keep them all. It’s a collection thing.
    But unlike Les Nessman – there are no bandaids on me. Is there a better tech out there? Sign me up!
    I still have about 3000 cds, but they all wav to me from the comfort of their own cozy NAS.
    Ah, Loni Anderson….. Sigh….

  9. “I wonder what’s next to come?”

    Vinyl made from digital masters. You already told us that. And I have verified it by listening to recordings from my own collection. Now tell us why. This phenomenon defies logic.

    1. From about 1975 there were an increasing number of vinyl releases made from digital masters, made using Denon equipment. I have one or two, on Denon’s own label. The sound quality was terrific and people loved them. Now people complain bitterly when their vinyl comes from a digital source.

      Direct Metal Mastering was all the rage around that time, mainly in Germany. Octave Records remastered Otis Taylor/Hey Joe Opus, but I picked up on Amazon the original vinyl, which is a 45rpm DMM direct cut from a 24/96 master file, done by In-Akustik. The sound quality is terrific.

      1. Steven I have several of those Denon label vinyl albums that were recorded in digital. And they are each superb. High quality pressings, high quality covers and spindle holes actually centered. So I am in total agreement

  10. Given all of this why is it I still prefer vinyl playback and they sell analog copies of analog master tapes for hundreds of dollars?

    Is it just my system or did the little box for what kind of notifications you want disappear?

  11. Help! I get the following message when I try to manage my Subscription Comments:

    “You have request to manage another email address and this is forbidden.”

    What is going on?

  12. What’s coming next is the realisation that “magic” exists in nearly all recordings, no matter how old they are; and that limitations, bottlenecks and weaknesses of the typical replay chain is what holds back greater appreciation of what was captured or created … 🙂 .

  13. “…noise is now eliminated”.
    Not so.
    If you follow Rob Watts of Chord:
    He has found that reducing the noise floor below “audibility” has a positive effect — down even to minus 300 dB !!!

    Better. Believe it. Like when they upped power transformers beyond what was “necessary”

  14. Just as a thought, sometimes it’s the simplest things which get the job done. While it’s not HiFi, Motorola deals with noise cancellation on their handheld commercial and law enforcement radios, by putting an audio port at 90 degrees to the microphone axis. I’m sure there’s some tuning in the port, but it does a great job of eliminating noise.We might be surprised on how this problem is solved. And it has no wires, moving parts or electronics.

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