What is the modulated frequency?

• A. The frequency of the constant electrical pulse produced by an electrical stimulation device before modulation
• B. The frequency that can be changed during modulation and can produce a physiological response (0-200 Hz)
• C. The time between pulses
• D. The maximum energy delivered per second

Answer: (B)

In modulated electrical stimulation, the parameter you adjust to shape the nerve response is the modulated frequency—the rate at which the stimulus is delivered once modulation is applied. This is the frequency that can be changed during modulation and can produce a physiological response, typically expressed in hertz and commonly explored from near zero up to about 200 Hz. Changing this frequency during treatment allows targeting different nerve fibers and achieving various therapeutic effects, since different frequencies can produce different sensations and nerve recruitments. The frequency of the constant pulse before modulation is the carrier or baseline frequency, not the modulated value. The time between pulses is the inter-pulse interval, which is the inverse of frequency, not the frequency itself. Energy delivered per second refers to power or energy rate, not how often pulses occur, so it isn’t the modulated frequency either.