[phasetransition]

Minor pedantry: 10log(6/100) = -12.2, so you could sort of get the number stated if you assume they meant sound power.

These metamerial, interference based approaches, are not going to be broadband by the standards of physical acoustics.

This could be useful for helping cancel a particular harmonic of a helmholtz resonator.

The real question, to me, is does it still work at high transitional Reynolds numbers, or under full turbulent flow?

Source: End effects during transitional and turbulent flow for Helmholtz resonators (i.e. bass reflex ports) in high output pro-sound loudspeakers has been something I've played around with in the past.

[hatsunearu]

https://en.wikipedia.org/wiki/Fletcher%E2%80%93Munson_curves

If one attempts to figure out what the subjective, perceived numerical volume vs. actual dB SPL is for a large group of people, it roughly coincides with the dB SPL number.

Bit more detail: you play a 100dB SPL tone and tell the participant "this is a 100" and play a 0dB SPL tone and tell the participant "this is a 0" and play all kinds of other tones at various frequencies and sound pressures, you get that curve. The unit for this arbitrary scale is called phon.

[phasetransition]

I am aware :-)

See ISO 226:2003

[hatsunearu]

Oh yeah, just putting it out there in case people wanted to know.

[intertextuality]

The pedantry is absolutely correct; however most people (aka anyone who hasn't studied acoustics, etc) do not understand the differences in how it's measured. If you just say "this reduces sound by 94%" to a layperson they would assume it to mean "this makes something nearly quiet by reducing its volume by 94%".

Hence my criticism of the title.