Questions tagged [noise]

Questions related to aviation sound noise or regulations thereof.

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A very loud, short- lived howl

Within the last eighteen months, I'd say - commercial aircraft descending into Heathrow have started to emit a terrifying, short-lived but very loud whining howl when they pass over my house. They are ...
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8 votes
2 answers
438 views

At what altitude can the sonic boom no longer be heard at sea level?

As others have stated here, you can hear the sonic boom of planes flying by at a fairly high altitude, ~80 000 ft. At what altitude would the sonic boom no longer be noticable at sea level? To add to ...
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UK noise certificate for below 9000kg?

This is regarding UK regulation - The Air Navigation (Noise Certification) Order 1990. I am curious what is the reason of specify this particular upper weight limit here: "every propeller driven ...
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10 votes
1 answer
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What is this sound on a B737-800 Takeoff?

Does anyone know what this sound is at 12:56 on a B737-800 takeoff? The aircraft is N822SY, the airport is Denver Intl. Airport, and the runway is 34L. Thanks and have a great day!
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2 answers
450 views

Why are jet engines still so noisy?

In general, jet engines on passenger aircraft make so much noise that in a long-duration flight it becomes really tiresome and uncomfortable. Nowadays, technology is much more advanced than before. ...
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9 votes
5 answers
3k views

Does any of the hearing protection worn by aviation professionals use active noise reduction?

I have read that passive hearing protection (standard earmuffs/plugs) offer good protection against higher frequency noise but do not protect as well at lower frequencies. Supposedly active noise ...
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0 answers
202 views

What causes "the howl" on the Trent 700 engines?

Many people have noticed what they call "the howl" on the Airbus 330 with Trent 700 engines, usually for a brief moment when it breaks inertia from idle setting. It sounds like this: ...
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1 answer
138 views

Why do some Airbus jetliners at full thrust sound like turboprops? [duplicate]

When riding an A3xx I always noticed the unique "turboprop" like sound when close to full throttle. Why is that so?
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12 votes
1 answer
2k views

Why do flying wires hum louder in a sideslip?

Page 50 of the Feb. 2021 issue of the EAA's magazine Sport Aviation reports that Like any good vintage airplane, the Sea Bird likes to fly coordinated, and the flying wires will sing out loud if the ...
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2 votes
2 answers
247 views

Whenever I hear a plane throttling down quickly, what is happening visually?

I am completely blind and have heard this several times when I was at air shows. Then my friend sent me this recording of a crop duster spraying the fields, and I heard the same type of sound. It ...
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2 votes
0 answers
44 views

Why would changes in jet-engine power settings not result in changes in engine loudness?

My casual AAR reading has dredged up another counterintuitive detail of aircraft behaviour, this time regarding the relationship between engine power and engine loudness: 1.16.7.3 Sound Similar to ...
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Odd whining sound from planes passing over [duplicate]

I'm trying to figure out what is causing the sounds that I'm hearing from planes passing over my house. I'm located approximately 60 miles NW of ATL. The noise I hear sounds like a turbine rapidly ...
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7 votes
1 answer
623 views

What causes the horn-like noise during the start-up of some jet engines?

Here's the specific sound I'm talking about (it starts specifically 56 seconds into the video, as well as at 2:02 for the second engine): I've only really heard that ...
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2 votes
1 answer
146 views

Do thrust reversers make more noise than engine at same RPM?

I'm talking about general aviation jet engines here. I live near an airport and I rarely listen engine noise on takeoff but always hear one during landing. Would a jet engine at the same RPM make more ...
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12 votes
5 answers
10k views

What could explain the fact that during 1976-80, I used to hear commercial jets make sonic booms while flying overhead?

I've read on this site & on Wikipedia that there have only been a couple of commercial jet planes in history that have broken the sound barrier--either in testing (without passengers) or during an ...
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3 votes
0 answers
145 views

F-16: MAIN PWR ticking sound, what is it?

What is that sound that starts when MAIN PWR switch is turned on in the F-16? Its sorta like a fast ticking sound. Why is it there, what makes it, when does it stop? And is it also there when only ...
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2 answers
355 views

How to reduce the noise of the supersonic passage(bang)?

as you know the transonic phase is often associate with the bang. The principal cons of the transonic phase is the noise,it's why there is not supersonic passenger aircraft( cause the end of the ...
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3 votes
1 answer
509 views

What's the rattling noise on an A320?

I recently flew on an A320, and during takeoff when the aircraft was rotating, I heard a loud rattling noise. If I had to guess I would say it came from the gear below but I can't be sure. I was ...
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Could propellers benefit from the design of the Blue Edge rotor?

Source: wired.com If indeed the Blue Edge blades reduce noise by 50%, could the similar design be used on [forward-facing] propellers without a penalty in speed or agility?
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2 votes
1 answer
263 views

Could a shrouded fan blade with long chord length be efficient?

I am wondering if it would work to have a fan with two or three blades which have short-ish span and very long chord length, like half a rotation for each blade. Would a shroud (that is molded on the ...
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5 votes
1 answer
678 views

What’s that weird sound during spool up on some aircraft?

Some engines seem to make this characteristic “wailing” noise when spooling up. A good example of such is from 0:50 to 0:54 in the following video: . I’ve also heard ...
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18 votes
6 answers
7k views

Is an afterburner louder than the same jet engine without it?

I would speculate that an afterburner increases the noise because it is nearer to the exhaust. But it certainly causes so many changes in the exhaust flow that it could be less loud as well. It may ...
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11 votes
1 answer
6k views

Will you be able to hear a supersonic aircraft flying away from you?

I'm wondering if you could be able to hear the sound emitted by an aircraft say traveling at Mach 2 away from you. I wondered if it might shift the emitted frequencies beyond the audible range. Would ...
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2 votes
3 answers
221 views

Why are the first sounds of an approaching enroute airliner low frequency, booming ones?

Often I will hear an intermittent, low frequency, powerful, booming sound that resolves into that of an airliner flying enroute high (FL 300+) overhead. So the first sounds that an airliner flying ...
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11 votes
2 answers
3k views

Why is a Lockheed MC-130J Commando II creating such a loud droning sound?

Today I heard a loud droning sound which is really unusual in the area of west London I live in; so I went on ADS-B exchange and it showed a USAF Lockheed MC-130J Commando II flying literally right ...
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2 votes
2 answers
220 views

How does the noise of a 2-to-4-seat helicopter compare with that of a similarly-sized fixed-wing aircraft?

We are considering allowing helicopters on our private airstrip (2600 ft strip). Noise on the ground (and approach) is the concern from the community. Does anyone know approximate dB ratings for a ...
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16 votes
2 answers
9k views

What is the loud noise of a helicopter when the rotors are not yet moving?

What is the loud noise when a helicopter is ready to start flying, but the rotor is not yet rotating? For example at Trump's "chopper talk", when he is intercepted by reporters on the way to Marine ...
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35 votes
2 answers
8k views

Why don't modern jet engines use forced exhaust mixing?

Jet engines are noisy[citation needed] - even a modern high-bypass turbofan is still deafeningly loud compared to pretty much anything except the even-louder low-bypass turbofans or a turbojet (much ...
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11 votes
6 answers
3k views

Is ear protection necessary for General Aviation aircraft?

What would happen if someone flew a brand new Cessna Skylane/Caravan or a Robinson R22 without using earplugs or headphones? Would they get hearing damage or it would be just a little bit loud where ...
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4 votes
1 answer
1k views

What is the cabin noise hertz in typical commercial aircrafts?

In cabin, we hear noises in commercial aircrafts. Wondering if it is in general over or under 100 hz. There should be a band width. Thanks!
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0 votes
4 answers
277 views

Can ADS-B used for voice communications?

Everyone knows the radio communications doesnt sound great altough they work perfectly. But can the brand new ADS-B communications be used for carrying audio signal? Would it be clearer? The ADS-B ...
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0 votes
1 answer
1k views

What kind of microphones does aviation use?

Do they use the dynamic ones or cheap ribbon ones? Also why are these microphones so small? I guess they dont use condensers. (I am yet to see an 3.5mm jack (which is used both on the C172 and the ...
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12 votes
1 answer
2k views

What causes the sudden spool-up sound from an F-16 when enabling afterburner?

What causes the sudden spool-up sound from an F-16 when enabling afterburner? I've included a video to make it clear what sound I'm referring to: at 1:16, I assume ...
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2 votes
1 answer
310 views

What causes the nose landing gear knocking noise on a Boeing 777 while taxiing?

The NLG knocking noise heard on taxi-in to stand, what could cause this knocking noise?
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2 votes
1 answer
255 views

Can helicopter rotor produce infrasound?

While watching a Mil Mi-17 helicopter takeoff I experienced strange thing. The helicopter produces a lot of noise even when just starting the engines. But shortly before taking off the high-pitched ...
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2 votes
1 answer
825 views

What's the mechanical 'whoosh, whoosh' sound in this video?

Sound in question comes right after the warning sound at 22:57.
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8 votes
0 answers
710 views

Why are the cabin chimes one semitone lower on the Boeing 747-400 than on other aircraft? [closed]

I noticed that the cabin chimes on the Boeing 747-400 overall sound one semitone lower than on other aircraft, including the 737, 777, Airbus A320, and even the 747-8. The same semitone-lower chimes ...
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7 votes
1 answer
1k views

What are the unique sounds emitted by Embraer E190-E2 on final?

I live close to an airport where these aircraft frequently land. When the E2 is between 2-3 thousand feet, something which I can only describe as whale moans, is heard. I say they are unique because ...
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26 votes
3 answers
5k views

Why would a turboprop rev down just before going full throttle during takeoff?

The only turbprop I've travelled is the ATR 72. I've noticed that the props' rev go down (for like a second, the sound also goes down) just before engaging full throttle in order to takeoff. I've ...
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4 votes
0 answers
293 views

In terms of noise, how does a steep climb-out compare to a noise abatement procedure?

For airports in populated areas, it is common to implement noise abatement procedures. In practice, this means that aircraft reduce thrust on departure, so that noise is reduced in proximity to the ...
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17 votes
2 answers
5k views

Are there any reported cases of noise from helicopters causing damage to property?

In the Netherlands, three cases have been reported of Chinook helicopters' rattle noise (low frequency sound) damaging solar panels. The Dutch defense ministry recognises this problem and the lawyer ...
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6 votes
1 answer
708 views

Is there any way to reduce the noise and vibration in a C-130 Hercules?

We are using C-130 B and E Models with T-56 A-15 engines and Hamilton Sundstrand 54H60-91/117 propellers. A lot of vibration and resonance are felt on these military version aircraft even after using ...
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2 votes
1 answer
775 views

Why does the Apache create much more rotor noise than the A-129?

The AH-64 Apache attack helicopter was upgraded several times after its first flight in 1974. The Apache Longbow was a major upgrade which entered service in 2003. On the other hand, Agusta A-129's ...
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2 votes
2 answers
788 views

What are ways to reduce drag and noise generated by the landing gear?

Apart from using fairings, what ways are there, or have been studied, but not necessarily implemented in reducing drag and noise produced by the landing gear, mainly for commercial aircraft with ...
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2 votes
1 answer
391 views

What is the maximum decibel noise level of a stage 4 rated engine?

I was just wondering if anyone is able to help me. I need to find out, what is the maximum decibel noise level of a stage 4 rated engine (as defined by the Federal Aviation Administration)? Some more ...
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5 votes
2 answers
3k views

What causes the "growl" of some large turbofans at takeoff thrust?

There are some (all?) large turbofans which emit a distinct "growl" (some people call it a "buzzsaw" sound) at takeoff thrust. What causes it? I've seen it explained (as in this question) as the fan ...
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0 votes
2 answers
487 views

What noises are considered worrying on a passenger flight?

As a typical 'nervous flyer', I often find myself asking crew about a noise that they say is completely normal during flights. The thing is, I've flown a lot and still hear new sounds sometimes! For ...
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24 votes
9 answers
8k views

Why are winches not used for towing commercial planes up?

In this video a glider is pulled up by a winch on the ground, like this: (Source) I would say you could apply the same principles with bigger planes, possibly even using sustainable energy sources. ...
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0 votes
1 answer
155 views

How to deal with the noisy cockpit?

From the pilot perspective I want to know how to deal with the noise in the cockpit on the turboprop aircraft while long-run flights. The reason is old type aircraft with bad headphones which doesn't ...
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7 votes
1 answer
178 views

Do noise abatement procedures have an impact on aircraft emissions?

The ICAO has imposed Noise Abatement Departure Procedures (NADP1 and NADP2) in order to limit the noise impact of departing aircraft on communities living nearby airports. Could noise reduction lead ...
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