Expression Evaluator

Menu Command: Tool | Expression Evaluator

The Expression Evaluator is a versatile tool for manipulating and generating audio data. Expressions can be entered using the keyboard or by selecting an expression from the Presets tree list. For more detailed information, refer to the GoldWave Manual.

For example, to generate a simple tone (a sine wave), the mathematical equation is:
y = sin(2πft) where f is the frequency, t is the time and π = 3.14159...

To generate this function in the current sound:

1. Choose Expression Evaluator from the Tool menu
2. Type in the expression in the large Expression edit box:
   sin(2*pi*f*t)
3. Enter the desired frequency in the f edit box (500Hz, for example):
   500
4. Choose the OK button. Processing will begin.

Evaluation can be stopped at any time with the Cancel button.

Use the play button to preview the expression before evaluation. If playback sounds rough or distorted, increase the playback prebuffer/latency setting under the Device Properties to allow extra time for processing.

You can use the Expression Evaluator to implement new effects.

To create a tremolo effect:

1. Choose Expression Evaluator from the Tool menu
2. Type in the following expression:
   wave(n)*(0.6+0.4*sin(2*pi*f*t))
3. Enter the tremolo rate in the "f" edit box (4 per second, for example):
   4
4. Choose the OK button.

You can alter the depth of tremolo by changing the values 0.6 and 0.4 to 0.8 and 0.2, for example.