Multitask Noisy Speech Enhancement System

- Speech band equalizer
- Dynamics processing
- Noise gate
- Signal level limiter
- Clipping restoration
- Noise reduction
- Noise whitening
- Blind deconvolution
- Spectrum analyser
- Time stretching
- Spectral expander
- Fourier corrector
- Neural network corrector
- Decorrelation
- Joint approximation
- Homomorphic approximation
- Reverberation
- Synchronisation
- Normalisation
Contact info

Noise gate

Noise gate is a specific case of the dynamics processor. It removes parts of the signal with level below the selected threshold, which is usually equal to noise floor level and is well below the signal level.

The dynamic parameters - attack time and release time - control how quickly the noise gate reacts to the changes in input signal level. These parameters should be adjusted so that noise is removed in the parts of the recording where speech signal is not present. The attack time should usually be much shorter than release time. The attack time is usually tens of milliseconds (should not be too short), the release time - several hundreds of milliseconds (the end transients of speech signal should not be gated). The background noise coexisting with speech signal is not removed by the noise gate (it is not a de-hisser).

The noise gate module works similarly to the dynamics processing module. It is, however, greatly simplified: only one threshold value is used. The noise gate works on the whole frequency range. The user can change the threshold level, attack time, release time and gain smoothing factor. Attack and release times may be expressed in milliseconds or samples. The settings may be saved as a preset and restored later for reuse.