This help topic describes the audio effects that can be applied to any audio clip. The effects are found by opening the Effect Chain dialog by clicking on the star icon in a particular track's audio palette, or by right clicking the audio clip and selecting Track Effects.
To 'amplify' is to increase the loudness or volume of the selected region. To make a part of the recording softer or louder, select it and then use the menu Effects -> Amplify. The volume is entered in percent (100 being no change, 50 being -6dB softer or 200 being +6dB louder).
The chorus sound effect is used to make one voice or one instrument sound like 3 voices or instruments by playing the original with variably delayed and slightly pitch changed copies of the original.
Note: Chorus is a very useful way to make a mono source sound more stereo. You should convert your file to stereo within an audio editing application first before using Chorus.
A Dynamic Range Compressor limits the volume levels of a sound recording so that it stays within a certain loudness range.
An example of where it is used is in TV broadcasting, where it ensures that the volume levels of ads are perceived as being louder than the television program itself (without any change in the actual broadcast volume).
It also has a use for recording audio from one medium to another, where the two mediums are not capable of handling the same range of volume levels (e.g. A CD can handle a much greater range than a cassette tape).
The "Threshold" setting works by detecting when the sound recording volume exceeds a defined decibel level. It then gradually attenuates the sound to bring it down below the dB level, and does it in such a way that the listener will not be aware the attenuation is occurring.
The "Ratio" setting limits the amount the volume level of the recording increases at any one time. If, for example, you wanted the volume levels of a recording to only increase by at most 1/4 of the amount they would normally increase, then this would correspond to a Ratio of 4:1. So if the recording volume level increased by 8dB, then you would only hear a 2dB volume increase.
The "Limit" setting defines at what maximum decibel level the sound recording will be allowed to rise up to. So if, for example, the Limit was set to 0dB, then you will never hear the volume level of the recording get louder than 0dB. The Limit setting has similarities to the Threshold setting, but the main difference is that the Threshold does allow sounds to go above the defined decibel level (for a short time), whereas the Limit does not.
You will find that the minimum Limit volume you can set is the same as the maximum Threshold value. This basically means that, in any situation, the sound will start to attenuate at the threshold level, but will never be heard louder than the limit.
While normally we do everything to reduce distortion, sometimes you want to add it. It is popular for use with guitars. The distortion is measured between 0.0 (off and 1.0 clipping). You also specify the level where it kicks in in dB (default -8db).
For a more consistent sound, you should apply Dynamic Range Compression first before you add distortion.
An echo is a repeat of the sound after a short time (usually 400 - 1000ms). It sounds a bit like the person is in a large stadium or is shouting between two mountains.
To add echo select the region and use the menu Effects -> Echo then specify the duration and amplitude of the echo. The duration is the length of time after which the sound repeats - usually this is between 400 and 1000ms. The amplitude can be between 1 - 99% (99 being a very loud echo).
A Flanger sound effect is similar to the phaser except that the delay is slowly modulated over time. You specify the starting delay time (default 5ms), the frequency of modulation in times per second (default 0.5Hz which is 2 seconds) the depth of modulation (default 50%) and the wet dry gain (100% for wet, 0% for dry).
A high-pass filter (sometimes called a low cut filter) removes all low frequencies below a specified Hz. This is useful if you want to make your recording sound 'clearer' or less 'muddy'. It is very usual to use a high-pass filter of about 300Hz on all voice recordings to improve intelligibility.
Reverb is many small reflections of the sound that come after a set time. It usually occurs when someone is speaking in a room, hall etc. More reverb is called wet, no reverb is called dry.
Use the menu Effects -> Reverb and enter the reverb level and time. The reverb level is the amplitude - 99 is very wet, 0 is dry. The time can be between 100 and 800ms - 200ms sounds like a small room or 800ms a large hall.
If you add too much reverb it can sound like the person is in a pipe or in the bathroom.
Some effects come with a series of options known as "Presets". The idea behind presets is to save you having to fiddle around with the numbers, which is great if the numbers don't mean a lot to you. Instead, you can just browse the preset list and select the option which best describes the effect you are trying to achieve.