Any loudspeaker could produce any frequency from 0Hz up to hundreds of kHz.
That nominal frequency range you could find in loudspeaker characteristics does not mean that loudspeaker suddenly stop produce anything as frequency goes out of range. Range just means that outside of that rande sound pressure created by loudspeaker drops more than 0.7 times in comparison to average in working range.
It is just about efficiency, not the ability to produce sound.
You could take some loudspeaker large enough to see diffusor movements and apply something like 0.1 Hz frequency, i.e. 1 oscillation per 10 seconds and observe how diffusor perfectly moves in that insane slow rate.
You could perfectly produce all that 6-8 Hz with any loudspeaker, even small and high-frequency ones. Just result would not be as loud as for nominal range. Just add some more power and that's all.
There also such thing as loudspeaker resonance frequencies, manufacturers try to move them outside nominal loudspeaker frequency range to avoid distortions and make frequency response curve as flat as possible in that range, but resonances also does not mean loudspeaker could not produce sound on that frequencies, on the opposite, it will do it too well for normal functioning and could even damage itself if the input power will be too high.
6-8Hz sound really perfectly sensed by humans, despite being nearly unhearable. Loud enough sound of that frequency will be sensed as vibration or itch in the whole body. This itch is uncomfortable and many expirience anxiety. But this is only in case when this infrasound is powerful enough to cause itch in a body. With low power you will feel absolutely nothing, may be hear some buzz if sine wave is not clean enough.
Any loudspeaker could produce any frequency from 0Hz up to hundreds of kHz.
That nominal frequency range you could find in loudspeaker characteristics does not mean that loudspeaker suddenly stop produce anything as frequency goes out of range. Range just means that outside of that rande sound pressure created by loudspeaker drops more than 0.7 times in comparison to average in working range.
It is just about efficiency, not the ability to produce sound. You could take some loudspeaker large enough to see diffusor movements and apply something like 0.1 Hz frequency, i.e. 1 oscillation per 10 seconds and observe how diffusor perfectly moves in that insane slow rate.
You could perfectly produce all that 6-8 Hz with any loudspeaker, even small and high-frequency ones. Just result would not be as loud as for nominal range. Just add some more power and that's all.
There also such thing as loudspeaker resonance frequencies, manufacturers try to move them outside nominal loudspeaker frequency range to avoid distortions and make frequency response curve as flat as possible in that range, but resonances also does not mean loudspeaker could not produce sound on that frequencies, on the opposite, it will do it too well for normal functioning and could even damage itself if the input power will be too high.
6-8Hz sound really perfectly sensed by humans, despite being nearly unhearable. Loud enough sound of that frequency will be sensed as vibration or itch in the whole body. This itch is uncomfortable and many expirience anxiety. But this is only in case when this infrasound is powerful enough to cause itch in a body. With low power you will feel absolutely nothing, may be hear some buzz if sine wave is not clean enough.