8:00 "Listen to how the audio not only changes in volume but quite drastically in timber." You've just inspired hundreds of Eurorack fans to want, and a few designers to make an "acoustic low pressure module." Or you could simulate it: Get the frequency response at various pressure levels, recreate these with EQ/filtering, and make a "Voltage Controlled Air Pressure" module.
Anything interesting about how sound behaves in liquids/solids? Specifically how reflections work, and if an interesting/meaningful impulse response could be captured
Probably not unless the diaphragm and capsule housing were effectively a sealed chamber, creating a pressure gradient. As far as I know, the capsule housings of mics aren't sealed air tight so that there won't be pressure building on one side of the diaphragm from changing environmental conditions leading to inconsistent performance and potentially damaging the diaphragm.
1:54 According to Master Handbook of Acoustics by F. Allen Everest, it states that "Sound travels faster in warm air than in cool air causing the tops of the wavefronts to go faster than the lower parts"
I was always under the impression, that acoustic instruments sound better on some days and worst on others. I thought it was air pressure and humidity. Thank you for doing the experiments, very interesting, specifically how the timbre changes!
Humidity matters a bit for wood instruments, mostly longevity, but high humidity makes wood swell and turn slightly softer which affects the timbre of the instrument ever so slightly. Mostly it's temperature. As a wind player warms up on a cold day, his instrument drifts slightly flat. That has to do with the resonant cavity lengthening. Strings need to tune when temperature and humidity change the shapes of their instruments too. Once those compensations have been made, this video kicks in.
Prediction: Never heard anybody complain about the lack of sound up there, but given that further out we do lose sound completely, there will be a drop in volume at 8849m, but perhaps not more than, say, 2db, which nobody would notice, since it is dropping as people gradually ascend. Just my guess. But I wonder how the frequency response behaves when air density drops. Will look forward to the reveal.
But the howling winds would also be 18db quieter, presumably. My hypothesis: climbers don't notice the change because a) it comes on gradually, b) our brains are pretty good at adjusting volume, and c) it's such an unusual environment that they probably assume it sounds different because of the gear, etc. Maybe everyone thinks altitude causes tinnitus when it's really just the world being turned down?
This made so much sense for me for a moment there, thinking of the timbre change with the buddhist chants originating from the Himalaya ... but then I thought there's people all around the globe living high up in the mountains - and how does their communication work? ^^ wow, anyway, mind-blowing Video once more, Benn! Really learned so much again, thank you for doing this. You're amazing!
Education is fun :) takes me back to fluid mechanics in college - in aircraft performance circles we use the term Mach number as the non-dimensional speed of a plane. Mach 1 is defined as the speed of sound - but this value in meters per second changes with temperature and pressure (as you demonstrated!). Going Mach 1 at 10km altitude is much slower than at sea level. Fun stuff!
i have always loved the way sound / pa speakers sound in the dog days of chicago and any place so hot and humid one is making their own gravy there is a "SQUISHY" quality to it =)
I was wondering if the condenser capsule of the measuring mic is affected by the density... Does thicker air mean a more resistive front plate, thus less sensitivity & volume drop?
I'd definitely like someone who's actually been up there to chime in. I imagine conversation is already pretty hard up there because of the 80 mph winds.
Very interesting. I'd love to see more testing on other factors, like temperature, humidity, wind, etc. Another cool experiment would be to send up a balloon with some testing equipment. Then there's the psychoaccoustic side to it. Do you hear sound more loudly or quietly when under the influence of adrenaline, fatique, oxygen deprivation, etc.
I think that temperature will also influence the ratio of water (steam) solved in air, warmer temperatures leading to more dampening due to more mass per volume.
I love how even in a deep quest to answer a really complicated question, you're still dropping casual knowledge like "180hz is the average frequency of the human voice" which is incredibly cool to me and hard to even think about because is this average as in by dB or by most represented from 20-20k or what? Maybe I'm stupid but sound is so fucking cool
if music is a primary language with many dialects, how many are there? how many musical ABCs are there? is there such a musical dialect that would consist mainly of kinematically "correct" sounds? what is the correlation between the language of the people and their attitude to life?
Wonderful video, thanks for sharing this! I am left wondering if the geometry of your vacuum chamber is actually leading to acoustic interference that changes with the speed of sound due to pressure. Not to ask you to repeat your experiments :) but would the same effects hold if the equipment was surrounded by acoustic insulation? Would there be different results from using a chamber with a different size? I find the rise and fall of the filtering effect while the pressure is steadily increasing to be really strange, and I think interference might be to blame for this.
I suspect that size wouldn't matter. Tech Ingredients channel did similar sound suppression experiments using helium and changes in volume or distance had little effect. Most of the suppression happened at the air/helium interface. Although Benn Jordan didn't give details of his experimental setup, if the microphone is outside the chamber then the low pressure/high pressure interface would have played a big part in sound suppression. With both speaker/metronome and microphone inside of the low pressure chamber then it is the interface between vibrating solids and low pressure air that now matters most. The condenser microphone might also have been optimised for atmospheric pressures in much the same way our ear drums are adapted to sounds transmitted at sea level
Hmmm. I have seen more Everest/K2 documentaries than I would like to admit, but never, never, has anybody mentioned the sound loss. If it was -19dB, it would surely be an issue that people would be mentioning at one point or the other. Right?
Referee number 3: Nice. But let me be a bit sceptical about the experimental setup: What about the whitish noise that is generated when the valve is open? To me that noise sounds comparable in intensity to the sound source used for the experiment, drastically reducing the signal to noise ratio. I would have expected to see measurements performed at different pressure with the valve kept closed, instead of a single continue measurement with that noisy component. Less data points but more accurate. How different would be the final result?
@@BennJordan Aaah ok. Thanks for the answer (and for the video!). You took the A data point, just before opening the valve and the B, after all air is again in. You could avoid the noise by closing the valve at certain pressure values and measure, obtaining other interesting data. In particular, spectral analysis would be interesting since the change in timbre you beautifully pointed out (due to resonances change of the air-vacuum box system?). For that, white noise would be the ideal source rather than saw wave, I guess!
Also [watching in 2x], even though that last experiment was cute (in the sense that these sorts of experiments were done widely during the 17th century), using these mini-cases and just assuming it's a settled and closed case is pretty dumb!!! Remember that even though it might seem to you an impossible task (it probably is) to go through the complex theory involved does not mean that it is useless and replaceable with very primitive observations of a different system that you assume is equivalent.
Great info! ..to me that timbre change was very intresting! Can we conclude (oversimplified) that low frequencies have more difficulty traveling at high altitudes?
Who else was thinking about what that sound is like through a Wave table...? One of the most peaceful environments I have experienced, was at the top of Mt. Hood, in heavy snow. There is something about the silence, as the sound is stopped by thick snowflakes. The experience was more profound than the view, from the lookout point... especially coming out of the studio. Another great video! You guys should definitely hit the Pacific Northwest, on the way back, from NAMM.
Great Video! As a sound engineer for over 30 years I just moved to a much higher altitude than where my old studio was. I defiantly have noticed a difference in how sound systems seem to perform quite differently here verses sea level. This brings me to a question in regards to density. Since you used Mount Everest as you reference for the high point, giving you A -19db drop, is air density linear? If so, could you calculate the db drop for 7000 feet based on your Everest calculations?
Brilliant work. Loved the tank experiments. You did a heroic job AND pulled a virtual lightbulb out of your arse with sound effects. Broadcast history right there. .
wait wait, in the cold, atoms are further spread out? Doesn't cold increase air density?? At 2:14? Or were you stating "a theory"? Also I see that dense materials allow sound to travel faster, such as steel, but warm air (which is less dense than cold air) is faster for sound? What am I missing!
there is no sound in space though. The average molecule and particle density in space is 4 parts per cubic centimeter. No way sound will travel through that.
"there's no such thing as cold only the absence of heat" yeah but there's no such thing as heat either its just the average kinetic energy of the particles in a particular area, you can't have it both ways
I like to imagine you as a wholesome Ben Affleck version of Batman, using your extensive knowledge of general science and audio physics to explain to us the wonders of our world. What a treat.
Loved this Benn. You should talk to fellow You Tubers Matt Parker (Stand Up Maths) and YT Physics guy Steve Mould. I could see some really great collaborations!
And especially the Tech Ingredients channel. In their video "Helium is the World's Best Sound Suppressor" they did experiments such as playing the flute in helium and showing that sound suppression occurred independent of distance sound passed through helium. If Benn Jordan repeated the same for his low pressure experiment he might come to the same conclusions as Tech Ingredients did. Most of the sound suppression is accounted for at the interface between the low pressure and high pressure. This raises the subject of impedance matching which is where Steve Mould's video "There's a Lever in you Eat and it does Something Amazing" now is of particular relevance.
Are you dropping the pressure maintaining the temperature constant? Because if you are dropping the pressure, naturally the temperature will drop and that might have an effect.
Thunderf00t loves vacuum chambers. Collab? Also, with such a small chamber, would that chamber act as a resonant cavity... much like the interior of an acoustic guitar or violin? Less air would mean less energy reaching the body and bouncing into the microphone.
Well, after Benn and Venus Theory-Cameron climbed down the caves we expect their next mission is to climb Mount Everest and have a conversation to really find out the answer to this 🙂
In high school I played a pep band gig in the Cedar Falls, IA UNI dome. I played bass and the 300watt amp i use was inaudible inside that pressurized building. The horns fared a little better but not much. A couple years later the dome collapsed in a snowstorm and they replaced it with a metal roof.
