There are several common noise removal methods:

1. Noise door:

Set the threshold value of a level, filter out all the signal levels below this threshold, and pass all the signal levels above the threshold value (here, the signal level refers to the level of the sum of signal and noise levels). This kind of sound material with high signal-to-noise ratio does not need to be denoised. Rvox in wave plug-in is the effector of such a noise gate. How many parameters are appropriate? Generally, it is about - 50 ~ - 40dB. The actual background noise is not certain. Try it yourself. You can't hear the background noise at the correct position, but the minimum sound emitted by human voice is not filtered out.

2. Sampling denoising method:

This is a method for professional audio processing software to effectively remove continuous and stable background noise. The principle of noise removal is to sample the waveform samples of noise, and then analyze the waveform and sampled noise samples of the whole section of material to automatically remove noise. The advantage of this noise removal is that it can completely remove the noise, but the disadvantage is that it destroys the sound quality of the original human voice. The lower the signal-to-noise ratio, the greater the destruction. After this noise removal, the sound has a strong metallic smell. Therefore, this method is generally not recommended to denoise the singing voice. The key to solve the problem is to control the recording to a high signal-to-noise ratio in the early stage as far as possible.

3. Other noise removal methods:

Analyze the frequency band of the noise with the spectrum, and attenuate the signal level of the frequency band of the bottom noise through the adjustment of Eq. The signals in this frequency band of the original human voice are also attenuated, forming new problems and using less.

EQ treatment:

The spectrum distribution of human voice source is relatively special. In terms of its pronunciation mode, it has three parts: first, the music generated by vocal cord vibration. The pronunciation of this part is flexible, and the spectrum changes greatly due to different pitch and pronunciation mode; Second, the low-frequency regular script generated by nasal resonance. Frequency equalization can roughly separate these three parts of the spectrum. The frequency band used to adjust the nasal tone is below 500Hz, the balanced midpoint frequency is generally 80-150hz, and the balanced bandwidth is 4 octaves.

For example, 100Hz can be set as the midpoint of frequency equalization, the equalization curve should transition gently from 100-400hz, and the adjustment range of equalization gain can be + 10dB ~ - 6dB. It should be reminded that the monitoring speaker with weak low-frequency pronunciation shall not be used during the adjustment of this project, so as to avoid unintentional excessive aggravation of nasal sound. The frequency spectrum of human voice and dental sound is more than 4kHz. Since this frequency band contains part of the music frequency spectrum, it is recommended that the frequency band for adjusting the tooth sound should be 6 ~ 16KHz, the equalization bandwidth should be 3 octaves, the equalization midpoint frequency is generally 1 / 2 octaves, and the equalization gain can be adjusted down to - 10dB when the equalization midpoint frequency is 6800hz.

From the above analysis, it can be seen that when performing frequency equalization on human voice, broadband equalization with gentle curve shall be used as much as possible to enhance the frequency band in order to highlight a certain sound feeling. This is to make the spectrum distribution of human nasal sound, musical sound and dental sound uniform and coherent, so as to make its pronunciation natural and smooth.

The promotion of 1 / 2 octave narrow-band equalization is very easy to make the sound source strange. Although this equalization method can greatly change the sound color of the sound source, if it is not to produce special effects, the equalization of singing pronunciation should be based on the natural sound feeling. In order to carry out specific effect processing on the basis of not destroying the natural sense of human voice, 1 / 5 octave frequency range equalization processing can be used, including the following situations.

(1) due to narrow sound sense and lack of thickness, the attenuation treatment of 1 / 5 octave can be used at 800Hz, and the larger value of attenuation can reach - 8dB.

(2) the sound is very bright, but weak and lack of penetration. 1 / 5 octave attenuation can be used at 6800hz, and the larger value of attenuation is - 3dB.

(3) the sound of rolling tongue and toothed sound is sharp and solemn, and the "Shh" sound lacks clarity. The attenuation treatment of 1 / 5 octave can be used at 6800hz, and the larger attenuation value can reach - 6dB.

For the equalization processing of sound source, it is better to use the equalizer that can display the equalization curve. For example, the equalizer of all digital mixer has the function of displaying the equalization curve. In this way, the shape of the equalization curve can be seen during the equalization process, which brings convenience for future readjustment.

Generally, the equalization gain adjustment button on the equalizer of digital mixer is represented by "g", the equalization frequency adjustment button is represented by "F", and the equalization bandwidth adjustment button is identified by "F" or "Q".

Article source: Jiangmen recording production http://www.sjttv.com