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Did... no one read the article before upvoting? This can reduce specific frequency sounds by -12db, NOT 94% of "sound". Can /u/dang or someone edit this clickba

Did... no one read the article before upvoting? This can reduce specific frequency sounds by -12db, NOT 94% of "sound". Can /u/dang or someone edit this clickbait title? The wavelength of 100hz is 56.5 feet. While it may be possible that these rings can attenuate specific high frequencies, they don't [and cannot] reduce all sound in general. To say otherwise would be to defy physics. Assuming the rings aren't vaporware, they could work for specific, constant higher frequency sound sources, like machine hums as mentioned in the article. However, the rings' aesthetic would be useless inside of an MRI machine... There is a reason existing sound barriers aren't open, because even regular walls block high frequencies. (And not just specific ones that match to a ring's size). The best way to kill frequencies are thick objects (like walls). For a room (like a editing studio or recording booth), it should have a non-symmetrical wall with various recessed spaces to function as sound baffles, at the least. And lastly, these would be completely useless for low frequencies.

atoav 8y ago
A useful application would be e.g. in cases where you want to target specific frequencies AND airflow should be possible. So this could be useful for attenuating small computer fans by 12 db without or adding meandering pipes filled with absorbing foam. For general acoustics I'd stick to a accuratly calculated and well built diaphragmatic absorber or at least a helmholtz absorbers.
phasetransition 8y ago
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 8y ago
  https://en.wikipedia.org/wiki/Fletcher%E2%80%93Munson_curves 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 8y ago
    I am aware :-) See ISO 226:2003
    - hatsunearu 8y ago
      Oh yeah, just putting it out there in case people wanted to know.
- intertextuality 8y ago
  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.
delinka 8y ago
>Did... no one read the article before upvoting? Maybe. Probably. I'll upvote a headline so it ends up in my "upvoted submissions" list so that I can peruse that list and read things later that looked interesting. Then I'll unvote if I didn't like it. No, I have not yet adapted to the 'favorite' link.
kazinator 8y ago
-12 dB is 94%. 12 decibels is 1.2 bels. 10^(-1.2) = 0.063 so 12 dB down means intensity is reduced to 6.3%, or by 93.7%. -12 dB is a worthwhile cut if it can be achieved with a barrier that has some good qualities: being unobtrusive, reasonably light-weight, thin, cost effective, perhaps transparent or translucent, etc. If you double it up, -24 dB may be possible. Stopping sounds in higher frequency ranges has applications. It won't block your neighbor's thumping bass, but there are other situations that benefit from noise blocking, like appliances with motors.
rohan1024 8y ago
Because of these click-bait titles I am jumping to comments directly to see the validity of articles and I know I am not alone. This actually hurts submissions that are front page worthy.
esmi 8y ago
https://journals.aps.org/prb/abstract/10.1103/PhysRevB.99.024302 https://journals.aps.org/prb/abstract/10.1103/PhysRevB.99.02... Like you said, it’s not wideband. This implementation is a notch filter about 50Hz wide. Interesting if you’re looking to reduce a specific source, which can happen. For example to cancel fan noise.
kebman 8y ago
Isn't the wavelength of 100 Hz 11.25 feet? Am I missing something?
- intertextuality 8y ago
  Yes, I apologize. I wrote 100hz but I meant 20hz, which is 56.5 ft. [0] [0] https://www.jdbsound.com/art/frequency%20wave%20length%20chart%202013.pdf https://www.jdbsound.com/art/frequency%20wave%20length%20cha...

atoav 8y ago

A useful application would be e.g. in cases where you want to target specific frequencies AND airflow should be possible. So this could be useful for attenuating small computer fans by 12 db without or adding meandering pipes filled with absorbing foam. For general acoustics I'd stick to a accuratly calculated and well built diaphragmatic absorber or at least a helmholtz absorbers.

phasetransition 8y ago

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 8y ago
https://en.wikipedia.org/wiki/Fletcher%E2%80%93Munson_curves 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 8y ago
  I am aware :-) See ISO 226:2003
  - hatsunearu 8y ago
    Oh yeah, just putting it out there in case people wanted to know.
intertextuality 8y ago
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.

delinka 8y ago

>Did... no one read the article before upvoting? Maybe. Probably. I'll upvote a headline so it ends up in my "upvoted submissions" list so that I can peruse that list and read things later that looked interesting. Then I'll unvote if I didn't like it. No, I have not yet adapted to the 'favorite' link.

kazinator 8y ago

-12 dB is 94%. 12 decibels is 1.2 bels. 10^(-1.2) = 0.063 so 12 dB down means intensity is reduced to 6.3%, or by 93.7%. -12 dB is a worthwhile cut if it can be achieved with a barrier that has some good qualities: being unobtrusive, reasonably light-weight, thin, cost effective, perhaps transparent or translucent, etc. If you double it up, -24 dB may be possible. Stopping sounds in higher frequency ranges has applications. It won't block your neighbor's thumping bass, but there are other situations that benefit from noise blocking, like appliances with motors.

rohan1024 8y ago

Because of these click-bait titles I am jumping to comments directly to see the validity of articles and I know I am not alone. This actually hurts submissions that are front page worthy.

esmi 8y ago

https://journals.aps.org/prb/abstract/10.1103/PhysRevB.99.024302 https://journals.aps.org/prb/abstract/10.1103/PhysRevB.99.02... Like you said, it’s not wideband. This implementation is a notch filter about 50Hz wide. Interesting if you’re looking to reduce a specific source, which can happen. For example to cancel fan noise.

kebman 8y ago

Isn't the wavelength of 100 Hz 11.25 feet? Am I missing something?

intertextuality 8y ago
Yes, I apologize. I wrote 100hz but I meant 20hz, which is 56.5 ft. [0] [0] https://www.jdbsound.com/art/frequency%20wave%20length%20chart%202013.pdf https://www.jdbsound.com/art/frequency%20wave%20length%20cha...