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Hey folks,

I wanted to get some feedback on an issue that's been starting to bug me a little. As one who has used noise reduction software to some great results, specifically the Sound Forge Noise Reduction plugin, I realize its potential to help "fix" a recording with a certain kind of flaw (especially sound of a specific pitch or narrow region on the sound spectrum).

One use of noise reduction software which I feel actually decreases the quality of the music is when NR is applied to remove background tape noise. Has anyone else listened to a recording which was obviously treated to remove the hiss and noticed that the treble was all fucked up and the very quiet parts are shrouded or just disappear altogether or kind of bubble around hovering around the gate threshold? I have only used the SFNR and have noticed it is not very good at removing broadband hiss without affecting the music in some adverse way. I've found this to be especially annoying if any more than 8-10 dB of attenuation is applied. Maybe there are better algorithms out there for removing tape hiss.

I know that tape his can be really annoying especially in the quieter parts but personally my brain can filter it out pretty good and focus on the music. I can hear annoying artifacts with some shows and I feel it can make these recordings sound worse than before.

Here's an example: Dead 4/26/69 (owlsley cassette). However I have not heard the original, so I can't compare. Another is Phish 7/30/99, again, I can't compare because I don't have the original. One I feel stronger about is around is GD 12-14-71 hosted by jeffk @ shakedown. I have a copy of the un-filtered disc 1 of that show (thanks again Jeff) and I'd like to know what folks think, throw on the headphones and listen, compare, tell me what you think. An example to listen to is the high-hat in Sugaree. To me it sounds like somebody using scissors. And in the tuning sections. Mostly quiet parts and the treble.

[Note: I removed this show long ago, there is no shn login any more]

You can grab d1 at:

orf.cx , login shn passwd shntmp

This will be a temporary l/p, although I am seriously thinking of opening that machine. Anyone wanna buy me some disk space!?

More philosophically, I guess I'd just err on the cautious side with digital stuff on files. There are obvious places where it has huge benefits. With the hiss removal software I've experienced, and my own ears, I've come to the conclusion that the hiss removal leaves the music in worse shape than it was before. I guess I'm more used to hiss and turntable noise from having used those media for quite a while. And I am somewhat of an audio enthusiast and listen closely to a lot of music. I know how objective these things are, and realize that it's up to the individual when it comes to hosting the music, etc.........

Let me know what you think.

Leigh

Leigh:

SF has one fo the WORST noise reduction algorithms for high-end results that you can use. IN fact, it is down-right terrible.

The problem you have identified is a common one with NR software. If you want to have it work correctly and NOT take out much of the high mid area, yoi need to limit the frequency that the algorithm is applied to. But, if you use SF, you always will have a problem.

SF is a consumer product in 16 bit not designed for pro quality work. One of the best NR algorithms is in Samplitude 2496, but this a professional product selling for about $800. I use that in pro and home use with outstanding results. But I do a lot of work in 24bit/96k from analog sources which will blow away ANY 16 bit file. Bernie

Leigh,

I've also noticed this adverse effect of using noise reduction, and I can also cite the 4/26/69 show as an example (haven't heard the 7/30/99). Whenever I perform any kind of noise reduction (which isn't very often), I Cool Edit. Basically, I set the attenuation to a very mild level, so that some noise is removed but no noticeable artifacts are added (namely the mp3-ish "swirly" top end). Then, I use the FFT filter, which is more or less a graphic eq that lets you draw your own curve for the frequency spectrum (this is pretty cool because it gives you control over how steep the roll-offs are). I'll begin the attenuation between 8-10 kHz, and roll off gradually until around 12 kHz. By around 16 kHz, I'm cutting by around 12 dB. Any content above 18 kHz gets chopped. This type of roll-off tends not to decrease any meaningful musical content, but it definitely helps to attenuate the noise without adding any weird shit.

Hope this helps,
Bob

I agree that sound forge is less than adequate for hiss reduction. Like you, I use the high hats as the benchmark. It is a very fine line between hiss removal and total high end loss. If you like, I will send you a few examples of some of the work I have done. As you know, I use diamondcut32 and have had excellent results without losing the hihg end.

Adam

I agree with you regarding noise reduction - though the job you did on the 4/5-6/71 and portchester shows was great! Removing that godawful whine was a real great thing. However, noise reduction just to get the hiss out has messed up at least one cd I have (11/21/73 -awesome show!). There is a kind of whooshy effect to the vocals, and the cymbals sound very far away... I think NR should only be used if the music is incredibly annoying without it, and of course that is very subjective. You do well to urge caution. thanks for the music, and how do you ever get into shakedown - it has been full for the last few months solid!

aloha
JT

Hi Leigh,

I've done some noise reduction work too and here's what i think. For specific frequencies, the algorithms are fine, as you said. This is seen in the work you did to 4/5/71 for instance (which I actually uploaded to you.) (I didn't transfer that though, so don't blame me for the track boundaries!).

I've done a lot of tape hiss removal experiments, with cool edit, SF, and other programs, and basically I think it's better with the hiss than with the reduction. The reduction leaves this strange alien warbling in the quiet sections that drives me nuts...it's so unnatural.

i thought i'd send along what cool edit says about NR of tape hiss.

>Distortion effects may manifest themselves as a "hollow" or
>"underwater/burbley" sounding signal, dull sounding impacts, "rolly"
>high end, or a "computerish" mechanical sound. These effects, if heard
>at all, will fall off if the noise reduction level is reduced. The
>amount and type distortion depends on the type of noise that is being
>filtered. Adjust Smoothing Amount and Transition Width up or down to
>minimize these artifacts.
>
>Besides reducing the noise level, the type of noise that is present
>after reduction is entirely different than the type of noise
>beforehand. For example, if you are trying to get rid some "tape
>hiss" from a waveform, the tape hiss sound will completely disappear,
>and in its place about 15dB quieter will be completely different
>type of noise. This noise will contain all frequencies in different
>combinations, thus it cannot be reduced much further without noticeable
>signal loss. The new noise has a "burbly" or "bubbly" quality to it,
>and if amplified, sounds very harmonic--like those 1960's computers in
>old science fiction films. Because this is so much quieter than the
>original noise though, it can be quite acceptable.

All this being said, I did a transfer on an 84 FOB, and did tape his NR on both cool edit and SF. The quiet sections were unlistenable due to the alien noise, but no TOO bad with the tape hiss. With headphones on (sennheiser HD535) the treble distortion was unbearable.

Also, I have the unedited 4/26/69, and I find it to be quite listenable.

Later.

Mike

Leigh,

I agree 100%. I have used Cool Edit to reduce noise and the same phenomenon occurs each time. They specifically state this in the Help file (that it will occur) and I don't think there's anything that can be done about it. I don't use it anymore nor do I trade discs that have had it applied to them. What I don't know is how to rid the disc of a constant wine or annoying frequency that appears throughout such as the Capitol Theatre or Manhattan Center runs which I believe you've successfully edited. Any pointers you could pass on regarding this?

Thanks in advance.

Peace,

Seth Kaplan

Leigh,

I also have had mediocre to piss-poor results with the tape-hiss noise reduction function on Goldwave. Seems to depend on the frequency content of the recording and the amplitude of the hiss. It has been quite awhiIe but I remember looking at an FFT of a section of just tape hiss - seems to me there was a large frequncy range that made up the hiss and I thought at the time that you could probably quickly develop a notch filter(s) for the high amplitude stuff but that the large range of medium to low amplitude stuff in the hiss would be hard to eliminate without degrading the music. Hope that helps a little.
peace
Brian

Leigh Orf wrote:

> I wanted to get some feedback.... Has anyone else listened to a
> recording which was obviously treated to remove the hiss and noticed
> that the treble was all fucked up...

Absolutely.

> I know that tape his can be really annoying especially in the quieter
> parts but personally my brain can filter it out pretty good and focus on
> the music. I can hear annoying artifacts with some shows and I feel it
> can make these recordings sound worse than before.

Me too.

I haven't used Sound Forge, but I think I might get it and see how it is. I have used Cool Edit Pro. There is a feature where you can take a sample of the noise floor in a quiet part and apply the reduction based on those findings. I have found that if I don't try to go over 6db or so of change, that it comes out sounding at least a generation better, with very little, if any, change to the actual sharpness of the sound. In effect, it lowers the noise floor (raises the s/n) of the audio, without really changing the main sample. I was impressed. Really good analogs that only need tape hiss removed turn out awesome. However, things like a steady high pitched, extremely low power squeal (like from electronic interference while recording or transfering) artifact will remain untouched. In fact, they are invisible to any wav editing program I've seen yet.
If you have tried Cool Edit and think that I am way off base (due to your experience with it), please let me know so I can get Sound Forge as soon as possible.
I wish I could buy you some disc space. Alas, I am a broke mofo.
take care...............Rick

----
music washes away from the soul the dust of everyday life
~Red Auerbach
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Check out my CD-R list at -- http://www.ryco.org/list.html
support the Home Grown Music Network
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You might want to give Cooledit Pro's noise reduction facility a try. It's at http://www.sentrillium.com

I used it with the Phish 03-22-93 show with good results, to my ears at least. People who have used both Cooledit and Sound Forge have told me that the noise reduction algorithm in Cooledit is much better. Sound Forge is better at just about everything else, though.

Tim Keenan

Personally, i prefer to accept the hiss, if it's on the master, especially if the master is "old" or of historical value. I guess it has something to do with preserving the original material by not processing it too much.

From: "In Your Ear Records, Ltd."
To: "Leigh Orf"
Subject: Re: want feedback on noise reduction, especially tape hiss NR
Date: Thu, 2 Dec 1999 21:46:26 -0500

Leigh,

I've been taping for 25 years now and I totally agree with you! To me, the doctored tapes sound tha same as if you'd taped something without Dolby and then you play it back with Dolby C.....wretched! Quiet passages are totally frustrating for me to listen to.

On the other hand, this comes from someone who thinks he knows how to EQ a tape and has done so to hundreds. I guess we all think we know best.

Check out my list of old fogeys at www.iye.com/audio.html and www.iye.com/dead.html

Take care,

Christopher Zingg
In Your Ear Records, Ltd.
286 Thayer Street
Providence, RI 02906
Sell or trade your music at http://www.iye.com

Winner of RI Monthly's "Best Of RI" and the Providence Phoenix's Readers Choice awards

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>. Has anyone else listened to a recording which was obviously
>treated to remove the hiss and noticed that the treble was all fucked up
>and the very quiet parts are shrouded or just disappear altogether or
>kind of bubble around hovering around the gate threshold?

I have no idea what that means technically, I know little to nothing about using sound editing software, but let me see if you're talking about a thing I hear.. (in my best layman's description) The software seems to be able to peel the hiss off the spots where no real high end is, but it seems to leave scraggly edges around sounds like cymbals?

If this isn't what you were describing, that's a beef of mine with NR. I can tell right away without seeing the lineage most times when it's been used. I say leave em all alone, most of what the software can "fix" can be taken care of more effectively with a good equalizer without losing parts of the recording.

L@r

Hello there - My name is Jason - I work at a company called SEK'D . We make Red Roaster & a few other things . I have been told that our NR is the best aside from DART for removing hiss & among other things . I have recently done a JGB show for a friend that was on a little tape recorder . But it was really important to him since it was the show he met his now wife .SO I did it & it is OK . I find it annoying , but I think that some won't even notice . Also I have been taught that doing like 3 passes at 3db NR is better than one big swoop @ 10 etc ! Keep this in mind . Perhaps get our DEMO ? ANyway if you need anything let me know . However I will be quiting my job there to go back to school . Thank You very much ! I enjoyed reading your post ...
Jason

site -
http://www.sekd.com

It's been some time since I've played around with noise reduction and my experience is very limited, but here's my vague recollection:

Soundforge's NR = bad. What you want to do is select a portion of the song w/o any music...just noise. The very beginning of a tape is often good for this (not the very very beginning when it's still really quite...the part when it gets noisy). The important thing is that it is representative of the overall tape. Anyway, you highlight as much of this as you can and in the menu near the NR option you choose an option that is something like Analyze noise or analyze selection or map frequency, etc. And after you've processed this you can save it if you wish or I believe hit another button in that window (or perhaps you'll have to run thru the menus) and filter out those frequencies. When applying you'll be able to select the percent of the noise to filter out and I found if you filter like in the area of 75% or so it results in drastic noise reduction as well as keeps the treble nicely in tact. Sorry the lack of concrete directions, but I hope this helps. Unfortunately I don't have SoundForge installed on this computer. Lemme know how it goes.

Bryan

Hey, Leigh,

My name is Glenn Moses. I'm a professional audio engineer, and from years of listening, my ears are trained and tuned.

When I first heard about digital noise removal software, I thought it was what I was waiting for to clean up my old cassettes and vinyl, so I could print them to CD and preserve them. I was overjoyed at the prospect of restoring my favorite music to its former glory or beyond.

I routinely get my grubby hands on this kind of software. I try all of it, and play with it extensively. What I have found is the following.

Broadband noise reduction is always damaging when you apply it to an entire mix, especially when there is a crowd or cymbals on the recording. Thus, hiss-removal just sucks for all kinds of mastering, especially live source material. It doesn't do much damage if it's applied 6dB or less, but then again, losing 6dB is not worth using the NR software.

In the studio, hiss removal is, however, REALLY handy for rmoving hiss from individual, un-mixed solo instrumental tracks, particulary guitar and bass tracks, as preparation for mixing multitracked records. Used properly, this software definitely helps to clean up studio recordings.

Click removal software is incredible. I had a 1978 Genesis single with an extremely rare pair of B-sides on it. The record was unlistenable due to the noise. After de-clicking the record through the Steinberg De-Clicker plug-in in Cubase VST/24, the record became as close to new as I could ever hope for. Simply incredible.

From what I have read, it's best to de-click recordings that need it before you de-hiss them, in order to take a cleaner sample of the hiss for de-hissing software to learn from. This is important, because, on live material like Dead and Phish, the crowd can be interpreted as noise by noise-removal software. This is an oversimplification of how the software works; Hiss-removal is really not that intelligent an algorithm. But, essentially, the crowd and percussion confuse the noise-removal filters, and so, they get damaged. Sucks, don't it?

I can't wait until this stuff gets smarter. I'm sick and tired of getting .mp3 files and even CD's of rare, classic source that has been butchered and garbled by ignorant people that honestly think that they did a good job "cleaning up" the music! It genuinely hurts me, and it's usually a waste of my time to obtain that source.

If you have the patience and a LOT of time, I'm told that many moderate passes of the hiss removal process are much cleaner and more effective than fewer, more drastic passes. If you really want to kill the hiss, try knocking it down 3dB at a time, and listening to the preview before you process the file if your software allows. This is supposed to work, but it's time consuming as all hell. Above all, ***use your ears!!!*** They will not lie to you. So far, they've worked great for you. I'm glad you had the sense to throw out this issue to the community. Feel free to send this letter to anyone out there that you feel needs it. This is an issue dear to me, and the ignorance and deafness out there astounds me. I would love to be a part of the cure. I'd love to see hiss-removal get the same bad rap as Dolby noise-reduction has among analog traders (Dolby is excellent when used properly, but no one uses it properly, and it becomes dangerous. Bleh.)

Summary:

De-clicking = good
De-Hissing = bad

My conclusion for the time-being is to simply knock all of my source down to CD right now, as-is, before the masters decay any further over time. I'll process them later when the right tools arrive. My records are my babies, I'm sure you love yours, as well. If you want to dabble in cleaning yours up, just make sure that you keep a copy of the original, hissy, crackly source handy on disc as well, so that when the time comes that the right software is here, you can re-attack the problem properly.

Please, feel free to bother me with any technical questions you may have. If I don't have the answer, I can point you in the right direction.

You can find numerous resources through the web-sites and archives of Mix and Electronic Musician magazines. These are the major how-to trade publications of audio engineers world-wide. Bookmark these sites:

http://www.emusician.com

http://www.mixonline.com

I hope I've been of some assistance.

Peace, love, and music,

Glenn

just so you know, i have tried a piece of software called CoolEdit in the past that actually lets you "sample" the particular noise that you are trying to remove from the recording such as tape hiss, static, etc. and it completely removes that sound without touching any other part of the file. it's really quite amazing. i haven't used it in a while. you used to be able to download it from the web. i think they are charging for it now. If it still has that feature it is well worth it.

I know what you mean. I can't say that I've listened to the shows that you mentioned, but I have definitely heard some mixed results w/noise reduction. I'm more familiar w/Cool Edit's NR than sound forge though... I have heard some great NR'd discs...example: 11-21-73!! Recently, I seeded 7-13-85 to hatfield.etree.org. I used some NR on that to remove some tape hiss (though it was labeled as SBDmc>DAT>CD when I got it..). Check that out if you'd like an see what you think of results.

I agree with you 100%. There seems to be a maturation process amongst those that collect digital recordings. After discovering how to capture and process music, people's attention seems to turn toward correcting and improving the quality of items in their collection. I know I went through a stage like that, and I've seen others go through it as well.

I have been successful removing pops, "correcting" recordings by splicing from multiple "identical" sources and removing whines and whatnot with notch filters. In the majority of cases, removing hiss ruins the music.

I have had some success, though. 5.15.70 has Pigpen singing "She's Mine". I boosted the volume, then ran 25% noise reduction 4 times, and it sounds pretty nice. On 7.2.71, I ramped the 1st minute of "Sing Me Back Home" because it started very softly, then ran 3 rounds of NR at 25%. This one sounds pretty good as well.

On the other hand, I have several shows with that warbly sound that says "NR used here". I have tried running NR on a copy of 4.26.69 (Electric Theater) that I digitized from a 2nd gen cassette, but the results were awful. Personally, I feel that people should avoid using NR on traded material, unless the NR is clearly noted.

"When the chips are down, the buffalo is empty"

David A. Finney

Leigh,

Heres my take. Take it for what its worth, but I do audio mastering as a profession. There are 2 kinds of noise reduction: EQ based and sample based. Sample based NR takes a fast fourier transform, or spectrum picture of the noise. Then it removes that noise print in he sound file, based on 1 of 2 principles: masking or threshold. Threshold says if the frequencies represented in this noise print rise above a certain dB level, perform x amount of noise reduction. This kind of noise reduction, when used in moderation, with a sufficient and accurate noise print, can be effective and very gentle to the file. Masking says, if this noise print rises above a certain level AND the noise is not concealed by the regular music content, like cymbals, based on psychoacoustic principles (how our ears interpret sounds)then remove the noise by x amount. This can be very effective, but, if misused, which is very easy to do, produces a kind of high end warble, hollow, flange similar to the effect of MP3 compression (which is also a psychoacoustic based process).

So, without much more lecturing, noise reduction is a delicate thing. If the music source is of a good quality, and has a complex arrangement of sounds and the noise is not too severe, then Im all for it. If the program material is very noisy, or from damaged analog source or if the musical arrangement is simple (guitar and vocals) noise reduction of any significant amount usually does more harm then good. If the music is derived from some compressed source, such as MP3 or minidisc, I almost never use an NR.

My 6 cents.
Damon

Leigh,

With out listening to the original, I know exactly what you are talking about. The noise in the spaces is almost a warble sound, similar to the sound you get with a decompresion program. Glad to see this kind of discussion coming to light. I thought it was just my ears noticing the side effect of to much NR.

Take it easy, Bob.

Hi Leigh,

Just wanted to share my thoughts and experiences regarding digital noise reduction. Sorry if any of this seems long winded.

From the recordings I've heard (GD 4/26/69 & 12/14/71) I agree with you in that they sound very unkind to my ears. I think this comes from the users not being familiar with the NR software and it's various settings and options, resulting in the problems you describe - overprocessing (removing too much desirable signal along with the hiss) and high pitched artifacts

I've used Sound Forge NR a lot (mostly for cleaning up old AM radio recordings & but i've also done some musical stuff ) and have gotten terrific results. I've found the key is using the highest resolution and quality settings. I usually take 3 or 4 different noiseprints and then tweak out all the other options till I find out what sounds best. Below I'll discribe some of the most vital setting for getting a clean nr job.

Try jacking up the fft window (start at 4096 and work up) and the noiseprint's fit size (1024 and up) , this will ensure you remove only hiss and don't leave any crap behind. Note that by using high values for those settings will greatly increase processing time but those are the two most important settings for eliminating artifacting.

The other important setting is the amount you reduce the noise by. This is totally subjective based on the recording you're working with but I generally find you can only remove up to about 10-12dB of noise before you start degrading the signal. When adjusting this setting I often find myself focusing on cymbals - using too high a setting will clip the high end and cause cymbals hits to sustain unnaturally. Too small of a setting won't remove enough hiss. Don't be too heavy handed with this setting - imho, less is more.

Lastly, I choose Sound Forge NR for two reasons - it's speed, even with a large fft window size and highest quality settings selected I can still process in approx real time (with a 400mhz PII). The best feature is the real time preview, this is invaluable for fine tuning all the options and finding the best settings. Neither Cool Edit or Dart have that feature.

BTW I would love to get my hands on a unprocessed copy of 4/26/69 and try my own hand at cleaning it up.

Food for thought,
Rich