Modulation effects refer to changes in the characteristics of a signal, often in communication systems. These effects can alter aspects like amplitude, frequency, or phase, allowing information to be transmitted over various media. For example, in radio broadcasting, modulation helps transmit audio signals over long distances by varying the carrier wave. In audio processing, modulation effects can create unique sounds by altering the original audio signal. Techniques like tremolo and vibrato use modulation to change volume or pitch over time, adding depth and texture to music. These effects are widely used in music production to enhance creativity and expression.