A more advanced and arguably quicker solution to background noise is to use a dedicated noise reduction processor such as the ERA 4 Noise Remover and ERA-D. These plugins work by using a noise profile to address the problematic frequencies and provide an excellent way to clean up the rumble and hiss accompanying outdoor recordings.

The ERA 4 Noise Remover has fewer controls and to get started all you have to do is increase the Processing control. By default the plug in processes the whole frequency range, however you can also use four further Focus settings to direct the processing to specific frequency ranges. Two options address the high and low frequencies specifically and are great for removing hiss and rumble respectively. A third option focuses on reducing the mid range noise, which is where you’ll also find speech. The final option combines the high and low options, leaving the speech area unscathed. Processing tends to reduce the overall level, so use the Output gain to compensate. 

Just be aware that the more you turn up the Processing control the more unpleasant artefacts creep in, and these can add a wobbly or watery effect to the sound. Even so, by selecting a suitable Focus option it should be possible to achieve a natural and considerably improved result. 

ERA-D is a more complex processor and although noise reduction is achieved with a single knob setting (De-Noise), there are various advanced parameters including noise Type, adaptation speed (Time Constant) and Arftifact Control. The 3 noise Types use different formulas and deliver different processing intensity (Type C is the most subtle). Meanwhile the Artifact Control lets you decide how much to suppress the undesirable sounds created by the noise reduction process.  

The most significant advantage of ERA-D is it provides multiband control. So you can adjust the Range (line) and Intensity (dial) of the processing for each band independently and also adjust the crossover frequencies between the bands. Factor in band specific Solo, and you have a more surgical toolset to drill down and remove noise without damaging your focus sounds.