Noise gating

Another reason for the success of STSA techniques in the field of audio engineering is maybe the fact that they have a very intuitive interpretation they extend to a large number of sub-bands the principle of well known analog devices used for signal enhancement, such as the noise gate [Moorer and Berger, 1986] (see also [Etter and Moschytz, 1994] for a link with compandors). 

From an experimental point of view, so as to remain in a linear domain, these applied stresses need to be low in amplitude (e.g. around 10% of the voltage or current). However, this amplitude needs to be significantly greater than the noise gate levels on the measuring device. 

Track FX are generally simpler versions of some of the other effects available from Sonic Foundry, such as the XFX series of plug-ins. Some types of effects work better on a project level, such as using Reverb to create a room atmosphere for an entire song. Some effects are best used at the track level, such as using a Noise Gate to remove the hum of a camera motor in the soundtrack of a video clip. Track FX are optimized for ease of use on tracks but can be used at the bus and project level as well. Likewise, there is no reason not to use ExpressFX or XFX on the track level either. 

Compression tends to increase background noise, especially during periods of silence. The Attack and Release controls can help eliminate this, but many times the only solution is to use a Noise Gate plug-in just after the Compression plug-in in the FX chain. 

More than one effect can be used at a time on a single track, bus, or project. FX are applied in a particular order in an FX Chain. The order of plug-ins can be important in the final sound. Some FX belong very late in the chain (such as EQ and Reverb) and some earlier (Compression). Others shonld be used in a particular order. Track FX plug-ins are usually applied in this order Compression, Noise Gate, and, finally, EQ. This is not a hard and fast mle, and there may be creative reasons why you d want to alter this sequence. FX chains and ordering are discnssed in more detail in the next chapter. 

Dynamic Noise Gate, Compression, Distortion, Dynamics, Graphic Dynamics, Multi-Band Dynamics... 

The first FX in a chain are typically the ones used to correct tracks with problems (such as background noise) or to clean up a sound to prepare it for later effects. The Compression plugin is frequently the first effect in a chain and is then quickly followed by a Noise Gate to remove any artifacts caused by compression. These both modify the level and dynamics of a sound, so the other related FX would also be used at this stage. Graphic Dynamics and Multi-Band Dynamics. 

Compression and Noise Gating in the Graphic Dynamics plug-in. 

What the Noise Gate plug-in might look like as expressed on the graph in the Graphic Dynamics plug-in. 

I cannot see any difference at all between the Track Noise Gate and the XFX Noise Gate, and it is likely that they are identical. 

In the Plug-In Chooser, double-click the Track Noise Gate plug-in and click OK... 

The Noise Gate plug-in will reduce all low-level noises below the Threshold level to zero, making these sections silent. The idea is to retain the content and eliminate the background (camera) noise, so you will need to play with the thresholds. There are a couple of other FX plug-ins types that are especially useful for camera noise ... 

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