It happens that when you record sound not in the studio, extraneous noises appear on the recording that cut your hearing. Noise is a natural occurrence. It is present everywhere and in everything - water from the tap is murmuring in the kitchen, cars are rustling in the street. It accompanies noise and any audio recording, whether it is a recording on an answering machine or a musical composition on a disc. But you can remove these noises using any audio editor. We’ll show you how to do this with Audacity.
Audacity is an audio editor that has a fairly powerful tool for removing noise. The program allows you to record sound from a microphone, line-in or other sources, as well as immediately edit the recording: crop, add information, remove noise, add effects and much more.
We will look at the noise removal tool in Audacity.
No “Noise Removal” button
Often, users have problems due to the fact that they cannot find the noise removal button in the editor. There is no such button in Audacity. To go to the window for working with noise you need to find in the Effects the item “Noise Reduction” (or “Noise Reduction” in the English version).
With Audacity, you can not only cut and remove noise, but much more. This is a simple editor with a bunch of features, using which an experienced user can turn home-made recordings into high-quality studio sound.
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How to extract sound from a video into a separate sound file
There are a lot of ways. In order not to clutter up the post with secondary details, I will briefly tell you about only three. Choose convenient for yourself.
- Through Freemake Video Converter freeware
- Using the paid program Total Video Converter
- By using your video editor. And you should have it. Especially if all or part of your business is on the Internet. Especially if you regularly shoot and upload videos to your site. Of course, if you want to upload a good video so that many people watch it.
The first two points should not be explained in detail. Everything is completely simple there, but if there are problems, write, I will explain.
I’ll dwell on the video editor in more detail. In the sense of how to extract sound from a video with its help. There are also a lot of video editors. I use one of the most popular - Sony Vegas.
Copy the captured video from the smartphone to the computer.
Via the File - Open menu, open the video file.
Now click on the button Calculate as.
and select the format of the saved mp3 file. Click on Custom ...
and select the save options. I recommend choosing Mono, a bitrate of 128 kbps and a frequency of 44 100 Hz.
Select the save folder and the desired name of the saved mp3 file.
We saved the entire audio track separately and now we will begin normalize the sound. I will sign everything step by step.
Step 1. Initial use of the Hard Limiter plugin
There may be spikes in volume on the recorded sound. If they are not reduced, then they are great annoying or may even stun. It can be a cough, a suddenly moved loud chair, a signal near a passing car, and so on. Therefore:
We click on the track properties control area with the left mouse button and thereby select the entire track
Then we go to the Effects-Hard Limiter menu ... and set these parameters
Click OK. Done.
Step 2. Sound Normalization
Usually, recording from microphones, smartphones, voice recorders is quiet so that it can be laid out right here in the form of a video on YouTube. So we need to raise the sound volume. But it is advisable to do this so that the sound rises, but not above a given limit. For this, the Signal Normalization plugin is used. It increases the volume, but so that the maximum amplitude is fixed. To do this, go to the menu Effects-Normalization of the signal ... Put in the window -3.0 db.
Click OK. We look at the result.
Step 3. Processing the audio file with the Compressor plugin ...
Continue use Audacity for sound normalization and at this step we’ll master the Compressor plugin ... I draw your attention to the fact that you need to process the track in this order step by step, without confusing and not jumping. Why do we need a compressor ...? The compressor averages, reduces the difference between the quietest and loudest sections. It happens that a person speaks into the microphone either louder or quieter, and with too much difference, listening to such a recording is uncomfortable. After processing by the compressor, the voice volume becomes more even, without jumps.
So we go to Effects-Compressor ... We set the same parameters
and click OK. We are happy with the result.
Step 4. Finishing with Hard Limiter ...
No matter how well the sound is processed by the Compressor, its algorithm also has drawbacks and under certain conditions it again picks out peaks. To avoid this, process the track again with the Hard Limiter plugin ..., just set the level to not -10, as for the first time, but -2.0 db.
That's just it. In most cases, these 4 steps are enough. Now we will consider more complex cases, namely:
- if the previous plugins - Signal Normalization ... and Compressor ... - didn’t do well with normalizing the volume along the entire length of the audio track
- and if the recording was at a high level of background noise, the refrigerator was working nearby, the fan was noisy, some kind of buzz, and the like.
Manual equalization of the volume of individual sections of the audio track
To do this, we use a simple signal amplification plugin. It acts like a volume knob. At this stage, its application is justified, since the sound has already been driven through the Normalization of the signal ... and the Compressor ... and in general is a diagram aligned without jumps. Only, as you can see, it is globally different in large areas. The previous plug-ins do not always do well with this “layout”, and so now we’ll fix it with our hands. I note that this situation is rare.
So, we select that part of the audio track where the signal level is clearly lower. We go to the Effects-Amplification ... menu and select the gain level to achieve equalization of the audio track fragments in volume. Look at the video how this happens.
How to remove noise from a recording
Please note that now I will explain how to deal with continuous background noise. If suddenly during a direct recording someone coughed, sneezed, something fell - this is not background noise, and if there is a desire to remove it, then you need to do this in other ways. And now we will remove the background noise. So, to remove the noise from the audio, you need to find a piece of silence on the audio track, select it and listen carefully. It is desirable that it contains only smooth background noise, without clicks and other “falling out” or eye-catching pieces. The better we select such a fragment, the better the program will cope with clearing the entire audio track.
To do this, visually select the plot with zero or so amplitude on the diagram and select it with the mouse. We click on the Play button in the Audacity button bar and listen carefully. If there are other single sounds on the background noise, then we try to find and select a fragment without them.
Having found the best fragment, select it. Go to the menu Effects-Noise-Create-noise model.
Then select the entire track. Go to the Effects-Noise removal menu. We leave these parameters
The only parameter you can experiment with is Noise Reduction. The very first field. I advise you to stay within 12-24 db. If done below 12, then the noise can be reduced very slightly. If done above 24, then distortion may appear in the remaining areas with sound.
Watch a video where I do all this:
That's all. The audio track is normalized, it remains to save it as a file.
Saving processed Audacity tracks to a separate audio file
This is done through the File-Export menu ... I draw your attention to the fact that through the File-Save Project ... menu you save the audio recording in the Audacity format and nothing more. In order to save in mp3 or wav format you need to use Export ... Next, everything is simple. Select the desired file type. If necessary, click Options ... and set the necessary parameters. For example, if you are exporting to mp3, then you can select the sound quality through the Settings. I recommend not to make it lower than 80 kbit / s and higher than 128 kbit / s. This is for voice, of course. If you wrote music and you need maximum sound quality, you can even put 320 kbps. Keep in mind that the higher the bitrate (this is the sound quality), the larger the resulting file will be.
So, from this post you learned how to use Audacity in terms of sound normalization.
Updated in December 2018 - This article was written in 2014. Over the past 5 years, by the end of 2018, experience has accumulated, the subtleties and techniques that have revealed:
- simplify the procedure
- reduce processing time and
- significantly improve the quality of the final sound
How to remove background noise in Audacity
The advantages of Audacity are that it is a free application and therefore more accessible to users. Audacity uses similar tools and techniques that are used in Sound Forge. To suppress background repetitive noise, a module is used, developed by one of the creators of the software, Dominic Mazzoni. The tool also analyzes a small fragment with noise and removes it from the entire recording. To apply an effect, click Effects - Noise Removal.
Then click "Create a noise model." So the application analyzes the frequencies that need to be removed. Then you need to select the entire audio file and restart the tool. The window that opens will offer a number of parameters that can be changed to achieve a better effect. Noise reduction, sensitivity and smoothing frequency. You can also adjust the attack time. This setting forms the response of the instrument to noise.
It is not always possible to find the part of the audio recording where there is pure noise for analysis. Sometimes this method of noise removal fails. But there is an alternative method of dealing with interference, although more complex. Just make another recording in the same conditions, in the presence of the same background sound. Then the noise can be taken from the new record. But this method is imperfect, because creating the same conditions for recording is not often obtained.
How to remove a squeak in Audacity
To create high-quality digitization or remove defects in audio files, you need to use not one tool, but all at once to achieve the desired effect. Audacity allows you to remove background hiss, as well as squeak. Some audio recordings contain frequencies with an unpleasant squeak, which is caused by strong interference from the equipment. To correct the sound, remove frequencies with unnecessary interference.
First you need to analyze the entire audio track. Frequency analysis is set through the Analysis - Build spectrum graph tool.
In this graph, you can see the frequency noise. It seems to bulge out of the whole spectrum of the chart. Find out the frequency of the noise. If you hover over it, the program will display the exact value that will be needed in the future. Therefore, remember it. After you need to select the entire audio track and click Effects - Nyquist Request.
A window will open where you need to enter the following:
- (vector (notch2 (aref s 0) 6230 50) (notch2 (aref s 1) 6230 50)) for several audio tracks,
- (notch2 s 6230 50) for one track.
The interference frequency that needed to be remembered is 6230. 50 is the value that needs to be changed to achieve a better result. In some cases, setting this parameter too high can adversely affect the quality of the original. To check if the noise has been completely removed, you can re-create the spectrum graph. Or a change in sound is perfectly audible.
How to remove pause noise in Sound Forge Pro
Sound Forge Pro offers users two ways to remove noise at once. The first is the Noise Gate. Many old films are quite noisy. Some are in no hurry to remove the noise, considering it a symbol of the music of past years. But the program allows you to remove hissing, and make it so that the main record will not be changed. You can enjoy old music without unpleasant sharp noise. The Noise Gate tool uses a filter that sets noise thresholds and removes unnecessary sounds if they match that value.
To remove noise, you need to open the file and find the place where hissing is present. Click Effects and Noise Gate. A window opens with the parameters and settings. The result of their change can always be pre-listened. Other tools of the program also have this opportunity, so working with Sound Forge Pro becomes more visual and convenient.
How to remove background noise in Sound Forge Pro
The program also has another tool - Noise Reduction. It can be found in the Tools tab. If the program removes unnecessary hissing, then the original sound is distorted, so-called artifacts arise - defects in the audio track. This is due to the removal of frequencies with noise, which leads to distortion. The recording takes on a cool metallic sound.
The solution to the problem depends on the type of noise. Indeed, mathematical methods are used to analyze it, so random noise and extra sounds will not be so easy to remove. But if the noise is cyclical, for example, due to electromagnetic waves, then it is possible to remove it. The Noise Reduction method is only used if the nature of the noise is cyclical. The instrument records background noise in its purest form, and then removes it from the entire track. To determine the need is not at all a large fragment.
With Noise Reduction, you can capture noise manually or automatically. With manual capture, the program will give you an image with control points. These points determine the nature of the suppression. The control points above the graph will be saved, and the lower ones will be suppressed. You can adjust the location of the control points to make noise removal more accurate. Or you can change the schedule so that the necessary information is not deleted along with the interference.
The Noise Reduction tool offers four noise reduction algorithms in audio recordings. They are located in the drop-down menu of the Reduction item and are called, respectively, Mode 0, Mode 1, Mode 2 and Mode 3.
In the initial settings, Mode 2 is usually installed. It is a standard option and helps with noise removal in most cases. But it is better to check all the algorithms. All audio recordings are of a different nature, so for some other algorithm may be suitable. The choice depends on the quality of the result.
- When using Mode 0, sound distortion often occurs and artifacts appear. Therefore, it gives the best result only with noise and low-amplitude noise,
- Mode 1 reduces the possibility of artifacts. Its action is similar to the previous algorithm. The absence of distortion is associated with less impact on the recording. This option removes light noise well.
- Mode 3 practically does not lead to the appearance of defects and distortions of the audio track, since the algorithm carefully refers to the original recording.
How to remove clicks in Sound Forge Pro
The difference between Audio Restoration and other noise removal methods is the suppression of clicks. The tool has parameters for removing background noise, it is possible to adjust threshold values. Click Removal Amount helps remove clicks. Its position can be adjusted to achieve the highest quality result, but usually it is in the standard position. Do not move the slider much to the right, as the program can remove not only clicks, but also the main part of the audio recording. Most often, along with clicks, if the Click Removal Amount value is incorrect, the sounds of the drums are removed.
To avoid the occurrence of unpleasant noise, noise, cod and clicks, you should use good quality equipment, record sound in appropriate conditions. But if there is no way to record audio in the studio, or if you want to digitize analog recordings, then you can use the correction using programs. You should not expect miracles, but means often just make the sound cleaner. To save old audio files, you need to experiment with the settings to achieve better sound.