Noise Reduction Manual

Noise Reduction Manual

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Unformatted text preview: n from the popup menu. You will not be able to make selections or adjustments to envelope points while in this mode. To switch out of Grab/Pan mode, right click on the noiseprint and choose Grab/ Pan again from the pop-up menu. Noise Reduction reference This section details the function of each control in the Noise Reduction dialog box. General page This page contains the most frequently-used controls of the Noise Reduction plug-in. Reduce noise by The Reduce noise by slider is at the top of the dialog on both the General and Noiseprint page. This control is used most often. This slider controls the total gain reduction applied to the noise. For example, a value of 6 dB means that a gain of -6 dB (50%) is applied to the background noise. A 0dB value means no noise is reduced, while a 100dB value means maximum noise reduction is applied. Settings of 10 to 20 dB usually provide good results on a single pass, but you may use higher settings with some types of source material. A higher number may improve noise reduction, but may add unwanted artifacts to the material you wish to keep. Start with a setting of 12 dB and adjust the Reduce noise by and Noise bias controls until you are satisfied. CHP. 2 NOISE REDUCTION 24 Reduction type (Mode 0, Mode 1, Mode 2 or Mode 3) The Reduction drop-down list appears on both the General and Noiseprint pages. It allows you to select among four different internal modes, or algorithms, to reduce the noise. In general, Mode 2, the default setting, will work well in most cases. However, it is always worthwhile to test all modes and select the mode that gives you the best results. The four Reduction modes each remove broadband noise in a slightly different manner. All modes use the noiseprint to determine what to remove from the audio, but interpret the noiseprint and remove noise using different algorithms. We recommend listening to the various effects each Reduction type has on the output sound. The Reduce noise by and Noise bias controls behave differently for each mode, so varying the three parameters while previewing will give you a good idea of how each mode affects sound. Noise reduction is dependent on your source material, so do not be alarmed if two modes sound identical in some cases. • Mode 0 uses the same algorithm as the original version of Noise Reduction. It is excellent for very low-level noise and can often reduce the highest amount of noise from a source. However, it is most prone to flange-like side-effects and squeaky artifacts when reducing too much noise or when the Noise bias is set too low. • Mode 1 is similar to Mode 0, but is less likely to produce artifacts; this mode removes less noise than Mode 0. • Mode 2 is the default Reduction type. This mode removes less noise than Modes 0 or 1, and it is less likely to produce artifacts. • Mode 3 is least prone to causing artifacts and often sounds much more natural and nonintrusive than the other modes. However, not as much noise is removed in some cases. When using Modes 1,2, or 3, the Noise bias control can make a large difference in the quality of the output. Also, the Reduce noise by control can be set higher than in Mode 0 without introducing artifacts. Note: The Reduction control is duplicated on the General and Noiseprint pages for convenience. NOISE REDUCTION CHP. 2 25 Noise bias (-20 to +20 dB) The Noise bias slider allows you to fine-tune the overall level of the noiseprint, much like moving all the noiseprint envelope points up and down would. Click and drag the slider handle to adjust the Noise bias setting. Although in general, a setting of 0 dB will be very effective, trying values between -6 dB and + 6 dB is recommended for maximizing noise reduction quality. Moving the Noise bias control above 0 dB has the effect of making the noise reduction algorithm remove more noise, but is more likely to cause low-level, non-noisy audio to be reduced. Noise bias levels below 0 dB will reduce the amount of signal attenuated, but if set too low, noise will remain in the audio. Note: The default setting of 0 dB does not modify the noiseprint level as in older versions of Noise Reduction. Since the Noise bias and Reduce noise by controls are interdependent, it is recommended that you adjust these controls until you find the right balance. When using Reduction type Mode 0, setting the Noise bias too low will cause electronic-sounding noise to appear on the output. When the Noise bias is set too high, the audio will sound dull since too much will be removed. Note: The Noise bias control is duplicated on the General and Noiseprint pages for convenience. Attack speed This control determines how quickly the noise reduction algorithm reacts to a noiseless signal. To change this setting, click and drag the slider left or right, or type a value into the edit box. The default value of 90 is recommended. Very low values often remove fast transients from a sound, while very high values can create audible artifacts during fast attacks. When using a very large FFT size, the Attack speed should be higher. CHP. 2 NOISE R...
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This note was uploaded on 05/15/2013 for the course EMUS 201 taught by Professor Pardal during the Winter '10 term at Life.

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