Queries regarding Audacity’s default compressor’s attack & release time

[BBC123]

I have been using Audacity 1.3 for a long time now. I have also used Adobe Audition for sound editing. After using Adobe Audition, I realized that the compressor of Audacity is slow when set on minimum attack and release speed. I know increasing the speed of attack and release increases the chances of skipping some samples. But at least Audacity could have provided some variety of speeds to choose from. I would like to try compression at release speed of 100 to 500 milliseconds. Can anybody tell me how do I do it?

[Essien]

The compressor of Audacity is meant for leveling he volume all over the audio file. It is not meant for maximizing the loudness. The only need of increased attack and release speed is when one wants to increase the sound above normal level. Leveling of sound needs low attack & release speed. This is the reason why no variety in choosing speed for attack & release is available. The default compressor will try to kick the speed if ever it crosses the threshold limit.

[DanielaA]

The default Audacity compressor is a software based module. It has limitations which does not let developer provide graph and curve editors to manipulate values and to control the speed of attack and release time, one needs to provide curves and graph editors for better and accurate control. Hardware compressors would need to implement lookahead for limiter stage by delaying the output signal. This delay can slow down the compression process frequently.

[Shurod]

Audacity’s compressor has a ‘Hold’ parameter which controls the intensity of audio to keep it under threshold limit. When audio crosses threshold limit, the gain level of audio gets louder to a lesser degree. When the audio drops below threshold, the audio reaches unity level. Hold works similar to fast attack and release speed but consumes less resources to achieve it. There is no standard way to implement & control the ‘Hold’ parameter. The compressor itself implements and controls it.

[-Deven-]

The audacity compressor also has a limiter which is an good alternative for fast Attack & release time. It displays a wave shaped effect. It looks at the instantaneous level of waveform and if it exceeds the limit of threshold then it is pushed back till it is at normal position. The picture below will explain how limiter controls audio signals that reach the thresh hold level.

When the limiter detects sudden increase in audio levels, it reduces the gain of the audio. The gain level is returned to normal when audio levels return to their normal levels.

[Erakna]

The hard limiter LADSPA effect chops off the top and bottom of the waveform. It also provides option for putting back the peaks after negatively amplifying them. This function is called ‘Residual Level’. If the Residual Level is set to high, the quality of sound is same as that of unprocessed sound. With Residual level set at 0.3 one can get a decent sound quality which will be better than the one generated using fast attack & Release time.