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That's how noise cancelling headphones work but it introduces audio artifacts that are often just as bad as the thing you're trying to remove. The thing most p

That's how noise cancelling headphones work but it introduces audio artifacts that are often just as bad as the thing you're trying to remove. The thing most people don't consider is that white noise (hiss, a fan) is readily tuned out by the brain - the brain is brilliant at reducing background noise - but artifacts introduced by artificial noise reduction are correlated to the signal and the brain interprets it as a distortion of the signal, not background noise. That's why audiophile audio engineers fix the noise instead of using FFT noise reduction - at least whenever possible.

b1daly 10y ago
This is true that the brain will filter out steady state noise, but this effect is much less strong once a signal has been recorded. Basically, on playback, the steady state noise sounds much louder than it did when you are actually present in the room. The same holds for the reverberation in a room, it will sound much louder on a recording than on location. For example, if you record someone speaking in a reverberant space like a church, it will sound like they are in a very reverberant space. Which they are, when you are listening live, your brain filters out the "non-direct" sounds so you notice just the voice. I'm pretty sure these noise filtering processes are related to the high priority the brain puts on understanding speech.
- riprowan 10y ago
  All true. However FM radio always has white noise, so adding a little bit to it is probably better than adding any correlated noise from signal processing. FFT noise reduction definitely has its place and I do use it from time to time. I just highly doubt "live on-air signal processing" is a good application given that the noiseprint is constantly changing.
- tacos 10y ago
  These broad generalizations about psychoacoustics are simply not accurate. It sounds like what every novice engineer experiences before honing his or her craft. If you're surprised by what you hear after recording something, either you weren't listening properly while recording it, you haven't learned how to record it properly yet, or your recording/listening environment itself is flawed. Of course we notice different things about an object after taking a picture of it. But you've got to be very careful about cause/effect/bias.
  - b1daly 10y ago
    I've been a professional recording engineer for 20 years. The phenomena I'm discussing is an objectively true, subjective perceptual effect, it doesn't change based on how long you've been recording. Over time you learn to expect it, but it doesn't go away. A lot of audio engineering involves working around the heavy real time signal processing our brain is always doing. That's interesting about animals. It seems likely that their auditory systems would be tuned for the type of stimuli that are vital for their survival. There would be a lot of overlap, but since it's hard to tell their subjective experience, it would take some clever testing to see how their perception of recorded sound would differ.
- tdaltonc 10y ago
  Non-human animals have all the same "noise canceling hardware" as humans (It's mostly in the hind-brain), so it can't just be for speech. I know that that echo/noise canceling hardware plays a big role in sound localization. This is probably why the noise and echoes sound louder on a recording. They don't change the way that they should when I move my head, so my brain can't figure out how to cancel them.
beat 10y ago
Having made a few records myself... when mixing with noisy source tracks, I generally choose to use console automation to mute the spaces between the notes, rather than trying to remove noise from actual signal, or even gate out the noise in the quiet spots. But it's more important to simply prevent noise in the first place. On the first record I ever produced, I was credited with playing "furnace". We were recording in subzero January weather in Minnesota, and the furnace in my basement was very noisy. I'd go and turn it off, and we'd track as quickly as possible before the house got unacceptably cold and the furnace needed turned on again. As an interesting aside, something a lot of newbie/hopeful audio engineers obsess about is "mic bleed", where the mic for one instrument picks up sounds from another. I mostly ignore this. Bleed is swamped by signal, and disappears into the mix. Even if a punch or edit fixes an error in the "bleed" instrument, it usually drowns out any error that remains in the bleed itself. Then again, audio engineering is full of a lot of nerding about second and third and even fourth-order effects, while ignoring first-order effects like "Is the song actually good?", "Is the performance good?"
- tdaltonc 10y ago
  > I generally choose to use console automation to mute the spaces between the notes. I recently had to make a promo video for my startup on short notice, with a less-than-idea setup, and I did the exact opposite. I filled all of the 'silent' parts of the video with 'ambiance' because the sudden drop to absolute silence sounded very jarring. I have no experience will audio engineering. I just thought it was interesting that we took opposite approaches to similar problems. https://en.wikipedia.org/wiki/Ambience_(sound_recording) https://en.wikipedia.org/wiki/Ambience_(sound_recording)
  - beat 10y ago
    Horses for courses. This is why a little background music can be helpful - it fills those silences. In the case of mixing a record, there are other instruments in the silences, so noise is just competing with music.
- riprowan 10y ago
  > something a lot of newbie/hopeful audio engineers obsess about is "mic bleed", where the mic for one instrument picks up sounds from another. I mostly ignore this. A better approach to "removing" bleed is instead to make sure the bleed sounds good. Euphonic bleed is solid gold.

b1daly 10y ago

This is true that the brain will filter out steady state noise, but this effect is much less strong once a signal has been recorded. Basically, on playback, the steady state noise sounds much louder than it did when you are actually present in the room. The same holds for the reverberation in a room, it will sound much louder on a recording than on location. For example, if you record someone speaking in a reverberant space like a church, it will sound like they are in a very reverberant space. Which they are, when you are listening live, your brain filters out the "non-direct" sounds so you notice just the voice. I'm pretty sure these noise filtering processes are related to the high priority the brain puts on understanding speech.

riprowan 10y ago
All true. However FM radio always has white noise, so adding a little bit to it is probably better than adding any correlated noise from signal processing. FFT noise reduction definitely has its place and I do use it from time to time. I just highly doubt "live on-air signal processing" is a good application given that the noiseprint is constantly changing.
tacos 10y ago
These broad generalizations about psychoacoustics are simply not accurate. It sounds like what every novice engineer experiences before honing his or her craft. If you're surprised by what you hear after recording something, either you weren't listening properly while recording it, you haven't learned how to record it properly yet, or your recording/listening environment itself is flawed. Of course we notice different things about an object after taking a picture of it. But you've got to be very careful about cause/effect/bias.
- b1daly 10y ago
  I've been a professional recording engineer for 20 years. The phenomena I'm discussing is an objectively true, subjective perceptual effect, it doesn't change based on how long you've been recording. Over time you learn to expect it, but it doesn't go away. A lot of audio engineering involves working around the heavy real time signal processing our brain is always doing. That's interesting about animals. It seems likely that their auditory systems would be tuned for the type of stimuli that are vital for their survival. There would be a lot of overlap, but since it's hard to tell their subjective experience, it would take some clever testing to see how their perception of recorded sound would differ.
tdaltonc 10y ago
Non-human animals have all the same "noise canceling hardware" as humans (It's mostly in the hind-brain), so it can't just be for speech. I know that that echo/noise canceling hardware plays a big role in sound localization. This is probably why the noise and echoes sound louder on a recording. They don't change the way that they should when I move my head, so my brain can't figure out how to cancel them.

beat 10y ago

Having made a few records myself... when mixing with noisy source tracks, I generally choose to use console automation to mute the spaces between the notes, rather than trying to remove noise from actual signal, or even gate out the noise in the quiet spots. But it's more important to simply prevent noise in the first place. On the first record I ever produced, I was credited with playing "furnace". We were recording in subzero January weather in Minnesota, and the furnace in my basement was very noisy. I'd go and turn it off, and we'd track as quickly as possible before the house got unacceptably cold and the furnace needed turned on again. As an interesting aside, something a lot of newbie/hopeful audio engineers obsess about is "mic bleed", where the mic for one instrument picks up sounds from another. I mostly ignore this. Bleed is swamped by signal, and disappears into the mix. Even if a punch or edit fixes an error in the "bleed" instrument, it usually drowns out any error that remains in the bleed itself. Then again, audio engineering is full of a lot of nerding about second and third and even fourth-order effects, while ignoring first-order effects like "Is the song actually good?", "Is the performance good?"

tdaltonc 10y ago
> I generally choose to use console automation to mute the spaces between the notes. I recently had to make a promo video for my startup on short notice, with a less-than-idea setup, and I did the exact opposite. I filled all of the 'silent' parts of the video with 'ambiance' because the sudden drop to absolute silence sounded very jarring. I have no experience will audio engineering. I just thought it was interesting that we took opposite approaches to similar problems. https://en.wikipedia.org/wiki/Ambience_(sound_recording) https://en.wikipedia.org/wiki/Ambience_(sound_recording)
- beat 10y ago
  Horses for courses. This is why a little background music can be helpful - it fills those silences. In the case of mixing a record, there are other instruments in the silences, so noise is just competing with music.
riprowan 10y ago
> something a lot of newbie/hopeful audio engineers obsess about is "mic bleed", where the mic for one instrument picks up sounds from another. I mostly ignore this. A better approach to "removing" bleed is instead to make sure the bleed sounds good. Euphonic bleed is solid gold.