The ratio of the expansion is equal to the compression ratio employed.
Threshold noise floor compressor.
The compressor adjusts the gain on audio below this background level so as to prevent it being unduly amplified in processing.
If your threshold is set to 20db your compressor will progressively respond to incoming signal within the range of 30db to 10db reaching 10db below the threshold and 10db above the threshold.
Sounds under the noise floor limit are considered background and are not amplified.
Relative amount of compression compared to the threshold.
Something around 50db is sufficient but may vary depending on how loud the recording environment was.
In short noise floor is generally the background noise you detect in a recording file.
This is mainly useful when compressing speech to prevent the gain increasing during pauses and so over amplifying the background noise.
Draw a graph in your head.
Unfortunately sound levels are often neglected during the procurement process.
The range of the expansion is equal to the amount of make up gain employed.
A 6 1 ratio is recommended.
In the image above this range is indicated by the dashed purple lines.
When it comes to noise floor keep always this in mind the lower your noise floor the better.
The level above which compression is applied to the audio.
Set the threshold to this db.
Although post construction sound treatment is possible it is also expensive.
Some best practices if followed during design and installation.
The noise floor feature behaves as an expander below the noise floor s threshold.
That noise is usually best detected when there is no other audio signal going along with it.
