How to DeHiss

1. Open the file that you want to DeHiss.
2. Go to the Restore menu and click DeHiss
3. When the DeHiss dialogue box opens up you should see a number of selections:

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• Gain: The gain is the main deciding factor as to how much noise is actually taken out of a sound file. If the gain is set at too low of a value you may get some residual noise. On the other hand, setting the value at too high of a level may cause the audio to become dull, muted, and/or distorted. Remember that even small changes in the gain values can cause significant differences in the renovated file.
• Smoothing Range: A spectral smoothing technique is used to reduce the residual noise. If the degree of smoothing is too low the renovated signal will sound rough and/or mechanical. In extreme cases it will be corrupted by a specific disturbance called musical noise - a random combination of different tones (as if someone was casually striking piano keys). If the Smoothing Ranges is too large, the restored signal may sound hollow and lifeless.
• Frequency Carving: Low Pass filtering is perhaps the simplest way of reducing broadband noise. Even though DeHiss and DeNoise suppress the high frequency components of a processed sound, you will often achieve improved results if some extra attenuation is forced into the range of high frequencies. The degree of high frequency attenuation is chosen in accordance with signal characteristics, e.g., to preserve rich sound of some musical instruments (a church organ for example) you have to use this tool with caution. On the other hand, without Frequency Carving, the renovated signal may sound mechanical and/or the residual noise may too emphasized.
        The choice of the rate of Frequency Carving depends on the Sampling Frequency. You can safely use large and very large rates for 44.1 kHz recording, but in most cases you should pick small or normal rates for 22.05 kHz files. The rate of frequency carving also depends on the noise level (for very noisy audio files, large rates are advisable).
• Frame Size: In the course of processing, the signal is divided into the partially overlapping analysis frames. Longer frames yield more uniform renovation results - use them when the signal to noise ratio is small. For high and moderately high signal to noise ratios try shorter frames because shorter frames will help you preserve freshness and liveliness from the original sound.
        Use shorter frames to process speech signals and longer ones to deal with songs and instrumental music.
• Overlay: You can use the overlay parameter to control the degree of frame overlapping. By decreasing overlays you can speed up the renovation algorithm - at the price of a slight deterioration (if any) of the restoration quality. Since short overlays may occasionally produce buzz-like artifacts, we recommend you use longer ones for high quality restoration.

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4. After Making the appropriate selections, you can click on the process button to begin the DeHiss process.
5. If you want, you can click the test button to audition your changes in real time mode.
6. To turn off real time, uncheck the online box

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