Sound is essentially physically described by the volume (sound level) and frequency (cycles per second). The picture shows the sound level (0 - 120 dB) above the frequency (32-16000 Hz).
The yellow line shows the human pain limit, which is 120 dB - this sound hurts.
The blue line shows the human hearing threshold, everybody hears frequencies different. Humans can hear sounds at 5000 Hz very good.
The audible voice and music of humans is between the human pain limit and the hearing threshold.
The approximate airborne sound insulation of 15 mm PhoneStar shows the white curve (details are registered in the measurement protocol). Multilayered PhoneStar systems are shown as orange curve (no measurements, only qualitative representation for clarity).
Where the human hears very well,
the PhoneStar sound insulation board absorbs best
The green balk shows the area where the human hears very fine and PhoneStar insulates the sound extremely good.
The black line shows the typical coincidence homogeneous materials, which generates little or no sound insulation in their natural resonance. PhoneStar has due to the inhomogeneous structure of sand no coincidence.