Help With Noise Removal In Classical Piano Piece

Hello everyone,

I’m fairly new to music production. After a lot of reading the basics, such as noise removal, I’m having the toughest time. I tried recording a short sample of a piano piece (line out to line in), but using the Noise Removal feature of Audacity doesn’t seem to let me get the job done without hearing distortion on the piano. No matter what settings I used, I could ALWAYS hear distortion.

I’m wondering, could someone see if they can try to remove the noise from this digital piano recording sample, without distortion? If someone can miraculously do it, can you please explain how you did it?

That would really be great. I’ve attached the audacity file (I have audacity 1.2.6, but I also have the newest one for compatibility). All I want is to have a clean sounding piano song =)

Thanks a lot.

EDIT: Just to clarify, I DID try doing the process properly, by making a pure-noise sample first. It’s just that when I try removing the noise on any filter level, the piano sound always seems to “dip” or sound impure or a bit electronic, if you get what I’m saying.
removenoise.aup (2.6 KB)

The attachment you posted is just the AUP file. It does not contain any audio. I’m not sure what the board limit is for attachments, but what we need is a WAV file exported from your project that contains a short segment of the noise you’re trying to remove and some of the piano. 10 seconds should be fine - that will be over 1 MB though. You may need to post it to one of the free upload sites and post a link here if 1 MB is beyond the board limit (which it might well be).

You’ve probably chosen the most difficult noise-removal task. Piano has an incredible dynamic range, sharp attack transients and note decays that can fall below the noise. You say you’ve tried all the settings. Have you tried just a touch of noise removal? Like 6 dB or 9 dB? Trying to remove too much noise will almost always affect the audio.

The Noise Removal tool is much improved in 1.3, so you might want to try that as well.

What is the source of the noise? Is this a live recording with air-conditioner noise and such? Low-frequency noise is the worst to try to remove. The filters can’t get the resolution needed to discriminate the frequency bands fine enough. One trick that you might try (and I’ve never tried this, but it occurs to me it might help) - apply the High Pass Filter to the noise before you sample it. Set the cut-off frequency to 200 Hz and the roll-off to 24 dB/octave. Then the Noise Removal tool will not see any noise below 200 Hz, and won’t touch the audio below that frequency.

There are some tips here:

– Bill

Another little “trick” that may help:

  • Use Audacity 1.3.x and make a copy of your “noise only” sample onto a new track (select, then Ctrl+D)
  • Amplify the copied noise by +6dB.
  • Use the amplified noise to create your “noise profile” in the Noise Removal effect.
  • Now apply Noise Removal with the “Noise Reduction” set to less than 12dB (experiment on short sections to see which gives the best balance of “noise removal : tinny distortion” - probably around 10dB)

Hey guys,

I tried playing around a bit more with noise removal, but I can’t seem to get any results without having a wavelike effect here in version 1.3. I’m not very familiar with all these different musical measurement settings, though. Here is a .rar file with the contents. It’s a sample of a song I’m trying to record.

If someone could help remove the noise as much as possible, without distortions, and explain how they did it, it would be great. Also, what are some good online guides for introduction to all these musical measurements and how they work, i.e. decibals?

Thanks a lot!

Well, I had a go at this in 1.3.11, and I have to say I’m stumped.

The noise level is very high. After amplifying the track so the peaks are at 0 dB the meters read about -44 dB on the noise only. It is also very broadband - almost white - noise, with some distinct tones in it (whistles).

No matter what I do with the sliders in the Noise Removal effect (in 1.3.11), I can hear the noise being modulated underneath the piano. This is actually worse sounding than just the straight noise.

How did you capture this recording? The piano sound is not bad, but the recording level is very low (peaks at about -15 dB), and the mic and/or pre-amp is very noisy.

– Bill

Also found it very difficult to produce a good result. The best I managed in Audacity was to use a low pass filter at 8kHz (virtually no piano sound present above 8kHz) then pre-amplify the noise sample by 10dB and use the smallest amount of noise removal that would produce a noticeable effect. Setting the attack/decay to 0.4 seemed to help a little at reducing the sudden bursts of noise, but still far from satisfactory. On the other hand, “Gnome Wave Cleaner” did a pretty good job (attached). (1.77 MB)


Thank you very much for trying, guys. Looks like it wasn’t just me. Although I must say, stevethefiddle’s try isn’t that bad!

In response to your question, I recorded it by simply connecting a line cable from Line Out on the electronic piano to Line In on the computer. I’m far from professional in recording, and don’t have the money to get high-tech pre-amps and other gadgets. So I just purchased a USB sound card to get the Line In port, as some online guides suggested. I doubt if I can make the actual recording any better. The input volume was all the way up (on the computer), and the output volume (on the piano) was very low, because anything higher distorted the piano sound.

Looks like I’m out of luck for a better sounding recording?

Thanks for the help anyways!

Are you sure that you used a “Line out” from the piano and not a “headphone out”? (headphone outputs are often more noisy than line-out sockets).

Again this makes me think that you may be using a headphone output on the piano, or a microphone input on the computer.
Connecting a Line out to a Line in should give a good level with both output and input level controls set to around 75%

If you are using the only sockets available, try turning down the level on the computer and increasing the level on the piano.

Yes, I’m pretty sure. It’s the same port that I use for connecting the speakers to the piano (using RCA). So it’s two RCA ends (red and white), the small size (I think 1/8"?). To be precise, it’s this wire: . That IS correct, right? Those plug into “L/R”, and not “L+R/R”, but I don’t think that matters.

Let me know if I did something wrong. When I have time I’ll definitely try again, while having the piano louder and computer softer.

Thanks a lot!

<<<the output volume (on the piano) was very low, because anything higher distorted the piano sound>>>

Distorted it where? How were you listening when it started to sound funny?

Who made the USB device? Part numbers.

You have all the characteristics – including background noise, of reducing the signal greatly so you can pump it back up again in the next device. Each pump adds noise.

Taking sound directly from a keyboard or any electronic instrument should give almost perfect electrical characteristics, not a performance that sounds like you put a good microphone in the room with the artist.


This six second thing was recorded exactly the way you’re trying to. Very Large Yamaha Keyboard headphone out into a Mac PowerBook Line-In.

Macs do this without the USB Device step, but you should be able to do as well properly tricked out with appropriate hardware. What is your hardware?


Hey kozikowski, thanks a lot for your help.

I just had some time to try out another short recording session, and I’m surprised to see that I can record at a higher volume now than before. I’m baffled = I know it didn’t work last time because I spent half a day trying.

Here is the result of the new recordings (two in one file):

The first was recorded at 70% both input and output. You can hear that there are quite a few crackles. The second was recorded at 60% both input and output. Only one tiny crackle now. I do notice that usually the crackles occur when the blue lines go off the sound track (when it’s loud). Perhaps that has something to do with it.

Do you think I should just leave recording as it is and not try to remove any noise? I can’t seem to do it without distortions. Also, I’m not sure why my noise is louder than that 6 second sample you showed me.


That’s clipping and is to be avoided at all costs.

What make and model of USB interface are you using? What settings have you made on the USB device (if any) and in your computer sound control panel? What make and model of keyboard are you using?

– Bill

Ah, so that’s it. I’ll definitely make sure to avoid that. Thanks for the tip.

USB: (no settings on it)
Piano: Yamaha P-80 (

Apparently everything works well now. Maybe I’ll just lower input or output level by another 10% and no more clipping will occur. So that problem has been fixed.

Now, in terms of noise, should I leave it as it is, since it’s not too bad, or try to somehow remove noise without distortion?

Thanks a lot for the help.

Is there not a switch for changing from microphone level input (very small signal) and Line level input (massively bigger signal)?
If there is a switch, then you have almost certainly got it switched to microphone and it should be set to Line.

Yes, that’s the Griffin iMic. I suspected as much when he said he was using a 1/8" input - the iMic is the only one I know of that uses that.

And yes, it does have a mic/line switch. Make sure it’s in the “Line” position.

– Bill


Yeah, I’ve already made sure it was on “Line” and not “Mic”. If I do switch it to Mic, the distortion and levels are indescribably bad =)

Did my latest upload with the new levels not produce the desirable results? I thought the new recording was quite manageable, although the noise level is still a bit higher than that 6 second sample recording that you posted.


Yes, that’s much better. If you select just the silence at the start and crank up the volume you can hear not only hiss but a bit of whistle. The manual for that keyboard is dated 1999. I think we may be hearing 10-year-old technology at work. On the other hand we may be hearing limitations of the iMic.

When you plug headphones into the keyboard and crank up the volume what do you hear?

If you set the keyboard volume to zero and the input volume in Audacity to maximum and record silence, what do you get? Then try several recordings of silence with the keyboard volume at, say, 3, 5, 7 and 10.

Finally, what do you get if you record without the keyboard connected to the iMic?

If the noise is from the iMic then you want to have the keyboard volume at the highest level that will not overload the iMic.

If the noise from the keyboard is constant for all volume settings, same principle.

If the noise from the keyboard is affected by the keyboard volume (which seem unlikely given the info in this thread), then see if you can find an optimum combination of keyboard output volume and Audacity input volume.

– Bill

The Famous Griffin iMic!

Famous for being one of the worst audio interface devices ever. They use battery from the computer to run their internal services and they’re not particular about how they filter or smooth it before using. This is the device that will let you hear the hard drive inside your machine start and stop because you can hear it clicking and bubbling behind the sound show. The iMic never had Line-In and Mic-In. It had a not strong enough Mic-In which was noisy and a Line-In that easily overloaded and created distortion.

Past that it was fine.

Shall I stop now? I put mine in the garage and I talked to one of the musicians at work and found that he put his… in a box in the garage. Best place for it.

You can help a little bit. You can purchase a wall-powered USB hub and run the iMic through that. The power to run the iMic will then come from clean, filtered wall power instead of dirty, noisy computer power. That might be all that’s needed to clean up the noise. Do not use the hub for anything else. iMic in, and output connected to the computer.


Thank you very much for the responses!

kozikowski: I just looked and happened to find a wall-powered USB hub. Didn’t quite help with the noise problem. The noise changed a little bit, but still has the same loudness. Here’s a really short noise sample, which you can compare with the previous recordings:

billw58: Here is an analysis of what you asked for:

When I plug in headphones to the computer, I get a standard noise. When I plug them in to the piano, I get the exact same noise, so I guess that’s a standard noise.

When piano volume is 0, or any volume at all, the recorded noise is always the same–the same loud one we’ve been trying to solve the whole time.

And, unfortunately, I can’t record without the USB device = My laptop doesn’t have a Line In port. So, I guess that question is still left unanswered, whether it’s the piano or the iMic.