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A rant on the hiss that's in so many orchestral libraries.

halfwalk

Active Member
I'm surprised no audio nerds here have chimed in on what I wrote above - that hiss actually makes the recording sound brighter, so much so that some engineers actually *added* it to early digital recordings!

In other words, you might be surprised that you actually miss the hiss.
It is a neat little psychoacoustic magic trick indeed. Plus, we're conditioned by decades of recordings to hear (and consequently tune out subconsciously) that sort of hiss, to the point where it almost sounds unnatural if it's not there, but just enough that you can't quite put your finger on it. Like the Haas effect or binaural beats, it's almost an "auditory illusion."

Isn't that kind of related to dithering, too? And the reason why someone like Chris from Airwindows wrote a dozen different dither algos, each with their own unique sonic fingerprint? Then again, to be honest I never quite wrapped my head around dithering, but I know that it involves noise being added to a signal for addressing bit resolution.
 

Nick Batzdorf

Moderator
Moderator
Isn't that kind of related to dithering, too? And the reason why someone like Chris from Airwindows wrote a dozen different dither algos, each with their own unique sonic fingerprint? Then again, to be honest I never quite wrapped my head around dithering, but I know that it involves noise being added to a signal for addressing bit resolution.
Right. Well, dithering is more subtle - or I should say the dither noise itself is, for one because it's at a much lower level than hiss, but mainly because it's designed carefully not to be heard.

The basic idea is that when you reduce the number of bits - typically when you go down from the 24-bit production standard to 16 for CDs (I know, what are those?) - what you lose is low-level detail (because you're truncating the bottom bits) and just cutting that off can sound harsh.

So dither is very quiet noise added to the signal that causes it to jump over the 16-bit lower threshold some of the time, thus smoothing the transition to silence. The best analogy I've heard is kids jumping up to see over the fence at a baseball game - they get a view every time they peer over.

However, the different flavors of dither get very tweaky. Not only is it noise-shaped, meaning it's at frequencies the ear is least sensitive to, it's designed to be decorrelated from the signal to help mask the effect.

You can hear the effect by recording a decaying note at 24 bits, possibly lowering it way down to make sure it falls into the bits you're losing, and bouncing that to disk at 16 bits both dithered and truncated.

Then raise the level way up and compare the two. You'll hear one fade out smoothly and the other cut off abruptly.
 
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Nick Batzdorf

Moderator
Moderator
I just remembered another analogy, or really a description: a noise gate chattering open and closed.

Another way of looking at the difference between dither hiss and hiss hiss: low-level detail, especially in spaces, is often below the level of the noise in a recording (and samples are recordings, of course).
 
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Headlands

Active Member
Are you talking about bow noise or room sound? The only noise I've really encountered is on the tails of certain libraries when you can hear the room hum pretty clearly if you're wearing headphones and you turn the volume up pretty high. But in a mix it's barely noticeable, and certainly doesn't mar a recording. If you're getting it on very quiet passages, welcome to the world of recording.
It's worth repeating: I'm ONLY talking about hiss, caused by mics, tape, or pres. NOT room tone or bow noise. Some libraries have it worse than others.
 

maxime77

Active Member
It's worth repeating: I'm ONLY talking about hiss, caused by mics, tape, or pres. NOT room tone or bow noise. Some libraries have it worse than others.
Is this room tone or hiss?

[AUDIOPLUS=https://vi-control.net/community/attachments/test-mp3.19122/][/AUDIOPLUS]
 

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halfwalk

Active Member
It's worth repeating: I'm ONLY talking about hiss, caused by mics, tape, or pres. NOT room tone or bow noise. Some libraries have it worse than others.
I understand, I only made the comment I did (about bow noise earlier in the thread) because in terms of frequency response, they are similar things, so denoising becomes a delicate baby/bathwater situation.

Funny how noise is so subjective, how one dev might leave it untouched while another goes wild in post. In the end, it's all just noise anyway. Music is just an incidental byproduct that only exists in your mind ;)
 
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erica-grace

Senior Member
It's worth repeating: I'm ONLY talking about hiss, caused by mics, tape, or pres. NOT room tone or bow noise. Some libraries have it worse than others.
It's worth mentioning, I think, that room tone will almost always contain hiss, while hiss does not contain room tone.
 
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Headlands

Active Member
Is this room tone or hiss?

[AUDIOPLUS=https://vi-control.net/community/attachments/test-mp3.19122/][/AUDIOPLUS]
That sounds like mostly room tone to me -- a noisy room. A buildup of that can and is an issue as well, indeed. I guess both are an issue, though for me the hiss is more of problem.
 
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Headlands

Active Member
It's worth mentioning, I think, that room tone will almost always contain hiss, while hiss does not contain room tone.
Yes, totally. What I hear in the sample libraries is more actual hiss from tape, pres, and/or mics. What we're hearing is a combination of the two, though very high end hiss is from the tape, pres, and mics in my recording experience.
 
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Headlands

Active Member
I understand, I only made the comment I did (about bow noise earlier in the thread) because in terms of frequency response, they are similar things, so denoising becomes a delicate baby/bathwater situation.

Funny how noise is so subjective, how one dev might leave it untouched while another goes wild in post. In the end, it's all just noise anyway. Music is just an incidental byproduct that only exists in your mind ;)
Agreed on all fronts. :)
 

germancomponist

Senior Member
Yes - but you hear the noise _once_ in a real recording, not multiplied by the number of voices you play. There's a difference between a "raw" and a simply bad recording. :)
I have not read all posts in this thread, so please excuse me if someone else has already suggested it.

When I use a problematic library, I bounce every midi-track into an audio track. Then I use a plugin like this in every single audio track:
It's time consuming, but because every single audio track gets his own best noice reduction preset, the end result of the mix is light years better than if I did not do it all.
 

Dietz

Space Explorer
It's worth mentioning, I think, that room tone will almost always contain hiss, while hiss does not contain room tone.
It's also worth mentioning that room tone doesn't suddenly disappear in digital black like it does in case of a "roomy" sample (... which is why noise sticks out like a sore thumb). :)
 

Wolfie2112

Senior Member
They must have superhuman ears, then. A couple of clients complaining does not make it a genuine problem.
In my case, it was in the quiet section of a cue, where it was a single string patch playing. With the CS2 patch I was using, the hiss (or room noise) was just too annoying, especially when the sample cuts off. Switched to a Hollywood Strings patch...problem gone. Some libraries are worse than others, and of course it's natural to have certain amounts of "hiss" but in this case it was sloppy engineering on the developer's part IMO. Hollywood Strings isn't perfect either...there'a few string patches where I can hear stuff like coughing, whispering, and even chairs moving. Quite amusing actually!
 
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