Question

In which of the following loudspeaker there is no diaphragm?

• A. Direct radiator
• B. Horn loudspeaker
• C. Indirect radiator
• D. Ionic loudspeaker

Hint:

Because plasma has virtually zero mass, ionic loudspeakers have an incredibly fast transient response and can reproduce high-frequency sounds up to $100\text{ kHz}$ with absolute clarity. However, they are expensive, generate toxic ozone gas, and cannot reproduce low-frequency bass.

Answer 1

The Correct Option is D

Step 1: Analyzing Loudspeaker Diaphragms:
Most conventional loudspeakers (including direct radiator, horn, and indirect types) rely on a physical diaphragm (a paper, plastic, or metal cone/dome) driven by a voice coil to push and pull air molecules, generating sound waves.

Step 2: Analyzing the Ionic Loudspeaker:
An Ionic (Plasma) Loudspeaker uses a completely different physical mechanism:

• It uses a high-voltage electrical discharge to ionize the air within a small chamber, creating a glowing cloud of plasma (ionized gas).
• When the audio signal is modulated onto this high-voltage electrical field, it alters the temperature and pressure of the plasma cloud, causing it to expand and contract.
• This expansion and contraction vibrates the surrounding air molecules directly, producing sound waves without using any moving mechanical parts like a diaphragm or cone.

Step 3: Conclusion:
Since the ionic loudspeaker operates without a physical diaphragm, option (D) is correct.