Infrasonic and subsonic?

Question

infrasonic and subsonic are the same?

and which devices can make infrasonic/subsonic,

I want to small devices. not to kill people, haha.

Answer 1

Subsonic is referring to a speed of an aircraft traveling through the air at a speed less than the speed of sound.

(the opposite of supersonic)

Infrasonic refers to "sounds" or air waves below a frequency of 20Hz. Those "sounds" are no longer perceived as tones by human ears. But if the amplitude of those waves is big enough, they can do harm. To generate Infrasonic waves that travel for some distances and can be detected some meters away you can not have a "small device" The minimum radius of the transmitting disc is given by Lambda / 4.

Lambda is the wavelength in air. Which is at 10 Hz equal to 30 meters (10 ft)

The diameter of your "small device" is at least 5 feet (1.5 m)

Answer 2

Infrasonic refers to sound frequency, subsonic refers to the speed of sound.