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With an audio cable, I have recorded my piano on a computer. One end is in the headphone output of my piano and the other end is in the microphone input of my computer.

Now I am trying to make the entire sound louder. I have tried this with the effect Amplify, but my problem is, the louder the music gets, the louder the background noises will be. To remove the noise, I have tried it with the effect Noise Reduction (with this tutorial) but then also the loudness will be removed.

I have also tried to duplicate the track several times to make the sound louder, but the louder it gets, the more noises/hissing I will get.

However, I don't understand why I get this background noise or hissing since I am not even using a real microphone. So the sound comes directly from the piano.

So how can I make the sound louder but without noises?

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    Same as your last question, you really need a USB interface that can take the line level from your piano. A headset jack is just the wrong thing to be recording line level into. You can get them for about $£€30 entry level. Buy one from a musical instrument retailer, don't try to get an even cheaper one on eBay, you'll get the wrong thing. See thomann.de/gb/usb_audio_interfaces.html
    – Tetsujin
    Aug 14, 2022 at 16:25
  • @user287001 the audio output of the piano is very good, with and without headsets. What I assume is that the level of the record was a bit too low. Microphone Array was set to 25 and Microphone Boost was set to 0.0 dB. I did that on propose, because I didn't want to destroy the quality of the audio, since the playing part can sometimes be louder than usual. Aug 14, 2022 at 16:27
  • @Tetsujin good to know. I will do that. Thanks for this info! Aug 14, 2022 at 16:29
  • Hi Reza. I edited your question to add more detail, e.g. I think you mean "Headphone output" rather than "Headset input". I tried to keep your tone and level of understanding.
    – n00dles
    Aug 16, 2022 at 23:34
  • @n00dles that's great, thank you! In the meantime, I have tried to record again, but this time with a higher record level. It was a bit too high, but in Audacity I could use the effect Normalize. It was good but not good enough, so I have ordered this interface: thomann.de/intl/behringer_umc404hd.htm Aug 17, 2022 at 13:06

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I'll try to go through this quickly :) and disclaimer: I'm not an electrician!

The first unwritten rule in noise reduction is to record with as little noise as possible in the first place. Correct connections are always the best place to start. Just because you can plug an output to an input, it doesn't mean you should.

What you're doing, is what a lot of novices try to do (nothing wrong with this, you just lack the knowledge for now). They expect to be able to connect anything to anything and get a good, clean signal. You can't do this because there are different voltage levels for different things. This begins with microphone level, which is extremely small. A 3.5 mm/1/8" mic input is expecting a small current that's induced by the microphone diaphragm, vibrating in sympathy with sound waves (I'm trying to put this in simple terms for you).
The highest-level connections are where the opposite must occur, a current must drive a diaphragm, like speaker cones in headphones. To get the power up high enough to effectively drive the speaker cones, the signal must be amplified.

So... You have an amplified output signal feeding a relatively sensitive input. That sensitive input may have voltage limiting circuitry which will pull down the amplified signal to a minute fraction of it's original level, or it will simply overload the input circuitry, either way, gain is then applied and by the time the signal gets to your recorder it's probably going to be a hot mess. Not to mention the fact that computer microphone inputs are usually limited bandwidth and have automatic dynamics processing applied to try to mitigate background noise between words.

A word on the noise-removal side: You can't, no matter how hard you try, bring up the rest of the signal through simple signal level gain without bringing up everything else, including any noise present. A common, quick way to make a noise floor less perceivable is to use a noise gate. Most telephone signal processing utilise noise gates to reduce noise between words. That is the simplest way to remove noise in the time domain. After that, you begin to use more complex spectral noise-attenuation techniques. But this is not what you need. You need to record a clean signal, and as Tetsujin said, the best thing for you to do is get a decent Audio Interface. You can then take the line out from your piano and safely connect it to a line input on your interface. This will dramatically reduce the noise floor of the signal.

References
Different signal levels explained simply
Another good user-friendly audio levels read
A conversation about this very thing on allaboutcircuits.com

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  • Very useful information. Thank you! Aug 19, 2022 at 19:40

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