2 Questions about Sound 

I am a professional acoustical consultant and have been working in the field for over 35 years. Everything stated by Jay regarding sound levels from these engines is gospel! Recording the sound will present technical challenges. Most microphones used in the recording industry will distort at these steady-state (not peak momentary) high levels of low frequency, unless very far away. You will likely require scientific use microphones that are capable of operating linearly in these high SPL environments, and in my experience, usually have low temperature limitations on preamp assemblies, etc. And relying on a phone ap for approximation of the sound levels will not be accurate either.....I deal with that all the time. Afterburner sound levels approach non-linear acoustical conditions where strange things happen that are too complicated to elaborate in a comment section. If you really want to record these sounds, do some homework before embarking on this journey. Thanks Jay......LOVE your videos and your informative descriptions of things.

My dudes I'm old enough to remember full-power ground test run-ups of old turbojets and early turbofans in 60's era passenger jets (even the latter could be heard literally miles away), and he is not shitting you that turbojets are even louder than you could imagine! Your hypothetical brain cannot process the noise, it's insane.. It is a shriek that'll haunt you the rest of your life if you're not prepared to hear something old like a j79 at full power

That second floor door looks a bit scary

There really is no describing the sound. I was working on a displaced threshold (this is when the runway is longer but is marked such that planes are not to land on the beginning of the runway) on a run way on an air force base. About 15 F-16 and F-35 came into land. We were about 1000 ft into the 2000 ft displaced threshold. Several planes landed which was pretty cool to watch from so close. It was loud but I could still talk loudly to the person next to me. Then, one of the planes decided to do a go-around and throttled up, they were about 300 ft elevation. The sound was so load there was no point in yelling to try to communicate. Then, the afterburner came on. Sound stopped having meaning, it was kind of surreal, literally the world went quite. It was like the sound processing part of my brain just shutdown. So I am standing there with no sense of sound at all, but my chest is vibrating so hard it was difficult to breathe. The best I can describe it is that it felt like my heart and lungs were being shaken to jello.

Bernoulli's equation is fundamentally about conservation of energy. A given parcel of air has some amount of energy from pressure and from velocity. If one of those goes up, the other must go down, otherwise we're getting free energy from somewhere else and that breaks the universe.

Love the t-shirt. Puttin

I would think a reasonable solution to getting a sound recording is that they send a nice audio recorder for you to keep, and record some audio whenever the next test happens? Cheaper than sending a person out there and you get a new piece of equipment. If they are just a couple guys that is.

Many years ago I was assigned to assist the jet shop of observing a startup and up to full power less water injection of the number two inboard engine a Pratt & Whitney J 57 on a KC 135 to visually check of the fix of turbine oil leak. I was instructed to stand facing the middle section of the J 57 about a foot away! To not move at all while looking over the engine during start up to full takeoff power less water injection. At full power I felt the pounding air vibration on my body head to toe, it felt like being surrounded by three boxers behind me and three in front of me punching pounding every inch of my body. I did not see any leaks, then out of curiosity I touched a fuel line NO vibration whatsoever, that with the air pounding my body made get nausea and almost passed out, I was lucky the jet tech running the engine throttled back and Me okay. Another quick run up then shutdown. I would never never do that again or with the GE J 79 with afterburner, good grief all the mini bones for hearing would be pulverized. So do pay attention to Agent JZ. He knows what he’s talking about!!

I've worked around PW-F100-229s. The engine is so loud in afterburner that with double hearing protection, I still have tinnitus. Depending on where you stand, the engine is so loud that your entire being is vibrating. You can't breathe. It's an indescribable experience.

My grandfather was a jet engine/load Master for 21 years...he used to tell me when he was in S.A.C....during the start to Chrome Dome....he would work on the b52 engine an he said the sound an the vibration up in an around the caling...that if you started to fell a poweder substance in you mouth it was your teeth vibrating together....✌️✌️👍👍

I did some recording of F18's in the 90s and one series was to record from startup/idle/100% to afterburner. With a huge amount of sound attenuation, way off axis and about a football field away we could get a non clipped recording of the afterburner. When the sound causes your eyeballs to vibrate and you want to curl up in a ball and go home you know would loud is.

it is amazing that the microphones or speakers on you guys' phones even work after being so close!

For anyone that wants to hear the noise level, I recommend going to a Cold War Fighter Jets Ground Run Day at the likes of Bruntingthorpe, where the crowd line is permitted almost right up to the runway edge, far closer than if flying was permitted. The jets, like the English Electric Lightning, will still use full take-off power for many seconds into the ground roll; when it passes you, the astronomical noise turns into excruciating ear pain. If you are not wearing ear plugs and or defenders, you will regret it!

I'm in New Zealand. I remember as a child hearing our then owned A4k Skyhawk's having a engine run up in the dence cool air of the night. We lived 6km's away from the air base. Although I wasn't loud, it was easily heard. The sound of a turbine engine is incredible

Fascinating. Thanks for posting.

ive been wondering about those inner perforations for quite a while, asked many people about them, finally got an answer! sweet thanks

Thank You for the time and efforts to share the content. Best Wishes.

wow, i thought it was just to get the airflow more straight. i didnt know it was for sound also. so cool.

big up AJZ last vid you discussed the thunder-crack of jet engine. Every year on Israel independence day they have flyby's-the whole IAF (this year was diminished due to post 710 trauma, so they did it only on Holocaust Memorial Day instead) still, no need to check the schedule! 1030 prompt you hear the distant rumble, and house shudder of the imminent jet-rage! so we all hit the streets and balconies to see f35/f15/f16 climbing from 10k ft upwards and it still is effing deafening

About 40 years ago I was at a airshow and they were demonstrating a Harrier jump jet hovering. I was watching from about a kilometre away. The sound went right through you shaking you from the inside out, it felt like it was going to knock the fillings out of your teeth.

I was lucky enough to visit the RAAF F111 engine test cell and stand next to a running TF30 at full AB. The only thing I can really compare it to as far as feeling the energy imparted is standing on the starting line at TopFuel drags when they launch. Its overwhelming the assault from it.

Thank You Agent JayZ

great video! Thank you for this. I studied at the Moscow Aviation Institute, and I think you are an excellent lecturer. I wish I had such a professor in my student days, you are cool :) Went back in time and nastalgized.....

One of your previous videos, was a great demo of just how much sound energy there is inside the building.. I believe it was a piece of 3/4 or 1 inch plate steel leaning against the wall. It vibrated and slid down like a piece of sheet metal.

I miss the crackle and thunder on my chest from the 737s taking off back in the 80s, before the bypass engines. Especially in the winter due to the dense air.

I got to watch a 737-200 take off 75 meters from the centerline. Loudest experience of my life. The JT8D engines are very loud compared to modern designs. I could feel the sound ripping through my body, similar to how an MRI feels. The sound pressure so much it was impossible to breathe, the sucking of air out of my lungs was stronger than my muscles to inhale. That must have been around 150 dB or so. That would put it around 170 dB being near the exhaust.

hmm, that door up there probably needs some caution tape :)

A very long time ago, I was helping develop the AV-8B simulator that was going to the Marine Corps. I recall that the simulation of the engine noise sounded pretty good, based on my years of working on A-4 Skyhawks. However, the Corps didn't like it because it didn't represent the sound heard by the pilot when wearing a helmet. I did get a few flights in the backseat of my squadron's TA-4's, and the sound in a closed cockpit when wearing a helmet is quite a bit different from when the canopy is open. IIRC, it sounds different at 500 knots than at low speeds such as 200 knots too. It's certainly not a simple problem.

The person that said "The hardest part of any journey is the first step," must've visited your building. ; )

I just noticed the jacket hanging in the background...

on our chinooks T-55s turboshaft engines, the intake to the front of the first stage compressor is about 2.5 feet with no sound ports and when those engines are running, you can hear the scream from the engines resonating from the intake. Sounds really cool, unfortunately, the straight cut gears on the transmissions drown that out at greater than 80% NR :(

Agent JayZed dropping some quid pro quo on the "Microsoft" guys...love to see it. And yeah, it's been cold. It was -17F (-27C) where I live when I woke up and headed to work at our local airport on Sunday 1/14 and hasn't gotten much warmer since then. Edit: fixed spelling

There are plenty of planespotting videos of military jets taking off with afterburners to get a good idea of the relative sound difference between full power and afterburner. These videos are shot from outside the airfield, so a very long distance. Usually you can barely hear the full takeoff power, but when the afterburner comes on it drowns out the wind noise at the microphone.

Great video. On the sound energy... I can imagine slamming the 20-40 KHz EQ range to zero. Even with all the sound mitigation in engines these days.... I'm 13 miles as the crow flies NE from Miami airport. I thought I was hearing ground runs. I watched FlightRadar24 -- I can hear East-to-West departures and it's enough to rattle window panes. I'm not complaining--I love jet engines, love learning about them, and knowing that my Christmas cards went out, and my FedEx and Amazon packages are on the way. :-)

Some Nokia phones had (~y. 2013) High Amplitude Audio Capture (HAAC) technology that could handle high amplitude noises (effective for both the quiet and loud parts of the sound). "A rock concert can easily reach 120 decibels, which poses no trouble at all for Nokia’s HAAC microphone. It can record up to 140 decibels with no audible distortion." The quality of sound it could record even in very loud concerts is still on another level compared to modern phones. There are samples online.

-30 temps. I cope with it by thinking of how hot it is on the Osh Kosh flight line. It averages out. Hope to catch ya there in 24'

Once attended a CF-18 afterburner run and we took turns going up and putting our hands on the fuselage right at the horizontal stab while it had the taps wide open. HO-LY SH-T. Every atom in your body is vibrating. The sound... the heat. Jeezus. Unfriggingreal.

I'm thinking if they are actually from Microsoft they wouldn't simply drop a comment asking for something. Companies that large do not operate in that manner.

The extension of the cowling reinforced with carbon fiber is for Sully's birdstrick!

Hello AgentJayZ ! I personaly know loud noise can and does make You ill ( have had experience of it ) it upsets something not sure what, and that is from 200 hp screw compressors, The turbines of Which You are speaking of perhaps could do much worse, The Jet Engine has to be the, or pretty close to the most Fantastic of the inventions/discoveries of the modern age! when a 68.000 lb Jet fighter is able to point nose up and hover along a runway well nothing short of incredible that is! also a reason We in the east have Natural Gas to heat things up on cold Winter days and nights! Enjoy Your Wisdom Sir! and the Jet Boats You have Shown Us and how they leave the piston boats like they are standing still ( I really wanted to say sitting in the dust however ! ) : ) Cheers!!! Rick from Ontario

Are the small holes in the intake anything to do with bleeding off boundary layer air too? I’m assuming the fan performs optimally with equal velocity air across its face. It seems like everything on a jet usually has more than one function!

Greetings from Greece!Do fighter jet engines & industrial gas generators get washed as airliner turbofans?How is this wash actually happen?Thanx AgentJayZ!

G'day Jay, Squeaking as an amateur Wind-Turbine & Propeller Carver...; I note the point that by Eliminating Blade-Tip Vortices, a close-fitting Ducted-Fan will be able to turn approximately Twice as much Torque into Airflow (Thrust) as a Free-Air Propeller the same Diameter... Part of the process is to Assure the Air is arriving at the Fan's Leading Edge at a Smooth Uniform & Linear Stream... And the Entry-Scoops upstream of Turbojet Fanblades & Stage-1 Compressors, In either Ducted Fans or Ducted (Thrustrum/Venturi/Ram-Air) Wind Turbines ; All serve similar purposes - ie to Precondition the Airflow Arriving at the First row of Rotating Blades... As I Undercomstumble it...(!) ? And, one May be Wrong... Such is life, Have a good one... Stay safe. ;-p Ciao !

-20 My wife lived in Winnipeg for 8 years while her dad did a uni course. We live on the Gold Coast, Australia and she is still Thawing out from 25 years ago 🤣 She does say though, the Canadian’s are the nicest people and the scenery is beautiful.. Hope to experience myself one day But in your summer 😁

It was -2F/-18.8C here in Idaho USA today. Everything metal is painfully sticky if not wearing gloves.

Id like to try the "wreak havoc of subwoofer" kind of recording. Is there an old video with that kind of feature ?

❤

The holes are possibly Heinhold's chambers.

and thats the truth!

Why is there a door in the middle of the wall above/behind you in this video? I hope there is a "Watch Your Step" sign in that room! 😄

Where’d you get that awesome CF - 100 cap?

I've actually thought a lot about recording audio from your engines too. Not for any reason, just for the challenges you described. It would be interesting to figure out exactly what equipment and techniques are necessary to get a clean recording that can deliver the essence of that sound. But who has the time? I definitely don't. :\

those Microsoft gamers ought to try and work out a deal with the U.S. Navy and get close to the catapult on a carrier with both jet engines in full afterburner up close and personal like we did back in the 70's with our USMC RF-4Bs with two J-79 8C's. Even with ear plugs and ear muffs, the sound was extremely loud. I could feel it in my the sinus bones in my gourd. Night launches were the best and being able to see the Mach diamonds

JZ, Bernoullis effect.. think of air molecules like cars on a highway. As they pass a speed sign they accelerate, each car moves away from each other. Air molecules that are farther away from each other is called “low pressure” and moving faster… As they reach the end of the highway they slow down and bunch up… high pressure .. simples ;-)

Air is not flung from the prop tips. Instead, "wingtip vortices" are a source of drag. Enclose the propeller in a tube, and that drag is eliminated.

So the holes are like Helmholtz resonators, right? That's pretty clever.

I'm wondering where most of the sound is coming from with a gas turbine engine... compression, combustion, exhaust (sounds like afterburn ramps it up substantially), bearings, auxiliary systems... or just everything combined.

All things considered I think it likely that strange jet engine sound request came from an independent modder. One working on a jet model for Microsoft Flight Sim. If they're actually a Microsoft employee working on Flight Sim it's strange that they'd reach out to you like that. MS is BIG. If a MS team designing a new plane model for Flight Sim needed engine sound bites, they'd put in a request to the appropriate department in Microsoft to acquire the assets. Some app team/group responsible for approaching other organizations to negotiate such exchanges. And that group would open up a search engine/phone book, find an airline or engine production business, and attempt to raise that organization's business inquiry contact, sales or similar, to make such a request. That's just my opinion based upon my experience working in a large corporation. But anything is possible. 🤷

Sir, i have a video request on HMU hydro mechanical unit.

Is this the first time we’ve seen the door open? Assume it’s either an office or an “office,” though I can’t imagine having to grab a ladder in an emergency. 😂

Agent JayZ, Urgent Message from Agent 99...lost Cone of Silence , Need yours immediately, Arriving Next Tuesday, or Thursday, Keep in contact ,Weather permitting ! Fort What ?

Watch the first step lol.

A melting pot with over 100,000 pounds of railroad wheels has the same effect. The sound does dissipate to a lower level after about 3 minutes. Still very loud though.

Get the to send you their sound recording equipment for a fee.

Sound guys... Rent an RV and camp close by

My sound question ... why do turbines whine?

3 quick questions/topics(if previously answered pls relay me): a)gas generators & trains b)gas generators & tanks c)how close relevants (if they are at all) are fosil fuel burning gas generators & steam turbines? p.s:bonus stupid question: if we introduced some water in the combustion event,could the produced steam be utilized & contribute to the gases that spin the power turbine?

neg 20 C is nothing. We were neg 30c in Chicago ...plus a 25 mph wind.