The reduction property of the DynamicsCompressorNode interface is a float representing the amount of gain reduction currently applied by the compressor to the signal.
The IIRFilterNode interface of the Web Audio API is a AudioNode processor which implements a general infinite impulse response (IIR) filter; this type of filter can be used to implement tone control devices and graphic equalizers as well. It lets the parameters of the filter response be specified, so that it can be tuned as needed.