Questions tagged [noise]

Questions related to aviation sound noise or regulations thereof.

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5
votes
2answers
895 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 ...
31
votes
2answers
4k 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 ...
10
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6answers
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 ...
3
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1answer
144 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!
0
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2answers
120 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 ...
0
votes
1answer
103 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 ...
3
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1answer
125 views

What are the triggers of the MD-80's takeoff configuration warnings?

I'm helping develop sounds for a MD80 simulation and I've noticed the MD has up to 5 alarms that fire when you advance the throttle and the aircraft is not properly prepared for takeoff: "Beep beep ...
10
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1answer
1k 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 ...
2
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1answer
197 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?
1
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1answer
108 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 ...
2
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1answer
364 views

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

Sound in question comes right after the warning sound at 22:57.
7
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0answers
359 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 ...
0
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0answers
228 views

What is the importance of Mach number (M) on shock waves?

My primary question is: what is the importance of Mach number (M) on shock waves? Although I believe confirming and/or answering the below will help clarify my misconceptions. When a wave moves ...
3
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0answers
317 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 ...
26
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3answers
4k 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 ...
4
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0answers
169 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 ...
15
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2answers
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 ...
9
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1answer
2k views

What did the “gear warning horn” on the North American P-51 sound like?

I'm working on a sound project for a P51 simulation and I'm having real trouble trying to find a reference on how the P51 gear warning horn sounded like. What mechanisms were used in the '40s to make ...
6
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1answer
449 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 ...
2
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1answer
407 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 ...
2
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2answers
430 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 ...
2
votes
1answer
222 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 ...
5
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2answers
1k 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 ...
0
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2answers
421 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 ...
20
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8answers
6k 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. ...
0
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1answer
110 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 ...
7
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1answer
150 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 ...
17
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3answers
876 views

When a typical commercial airliner flies overhead, what is the actual noise we are hearing?

We're all familiar of the sound planes flying quite high overhead and you hear a faint drone, even when planes are lower to the ground you hear them scream at a slightly higher pitch, but what exactly ...
4
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0answers
123 views

How do active blades work on helicopters?

Can someone throw some light on 'active blades' as used in helicopters? I'm mostly interested in the use of piezoelectric material and actuators. How are the actuators able to sense the change of ...
3
votes
1answer
292 views

What are the rules in the UK about overflying built-up areas for fun?

I live in North London. It's not like we don't have a fair amount of noise pollution from the sky, with helicopters, and jets landing at LHR with a stupidly shallow glide path angle. But in addition,...
17
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3answers
3k views

Won't sonic booms prevent Space X's BFR intercity transport plan from being acceptable?

Considering that Space X have just announced that their BFR can take anyone anywhere in the world in under 1 hour, that would be enormous speed, does this rocket not produce sonic boom? If not is it ...
0
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1answer
1k views

How loud is a private corporate jet? [closed]

It's a movie/TV trope that people can talk to each other and even whisper on commercial airliners in flight. In a story, it’s pracical to confront the reality of the experience and have characters ...
10
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1answer
598 views

In a piston aircraft, how much noise is generated by the engine, and how much by the propeller?

I've been reading quite a few articles lately about how noise complaints from GA airports across the country. One of the common suggestions to fix the issue is to simply use an electric engine ...
8
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2answers
319 views

Are there any methods to predict the location of a jet aircraft from its sound?

At times there are military fighter aircraft flying overhead of my location (MiG-21Bis and Su-30MKI). The first indication of their presence being the sound, that obviously causes one to look up to ...
10
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1answer
1k views

Is ultrasonic noise from small turbines painful to pets?

A question on another SE site prompted me to search for 'Aircraft engines untrasonic noise dogs', but with not much success. The OP's dog barked like crazy at turboprops, but was not bothered at all ...
6
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1answer
1k views

Can an airplane flying above 35,000 feet be heard on the ground?

Can the sound produced by a commercial aircraft flying at 35000 feet be heard on the ground when the surroundings are quiet?
53
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4answers
14k views

Can I stop crop dusters repeatedly flying over my home?

I have a crop-duster spraying the fields around me often. He flies over my house no matter what field he is spraying every few minutes. I think he uses my house as a pivot point. The old pilot rarely ...
0
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0answers
647 views

What is the noise that the A320 makes on the ground? [duplicate]

I've noticed that planes in the A320 family make a sawing noise on reaching the gate. The link below may give you an idea of what I mean (although the A320 in the video is still taxiing). Is this a ...
3
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1answer
499 views

Are some airline's flights more noisy than others for security reasons?

LHR has published a table ranking the noise and pollution levels of the different airlines using the airport. At the bottom of the list is Israel's El Al. El Al, in their official statement, say that ...
11
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1answer
3k views

What causes the distinct sounds of a jet engine?

I live a few miles from a major airport (BOS), under the path that a lot of airplanes use to depart. The planes are somewhat low over my house -- high enough that it's not deafening, but low enough ...
5
votes
2answers
903 views

What noise reduction measures were taken in the time between hush kits and chevrons?

In older jets such as 727 hush kits are used in the engines to reduce noise. In very modern jets such as 787 or 747-8F, chevrons are used for the same purpose. What happened in between? The switch to ...
11
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2answers
807 views

Can an airport fine an aircraft for being too noisy?

I stumbled upon this article (sorry, in French!) stating that in order to avoid fines, Ryanair pilots start take-off procedures at the beginning of the runway (rather than at the "intersection"), with ...
10
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0answers
1k views

How loud was the Concorde's sonic boom at the ground level? [duplicate]

Before the Concorde was sent into retirement, their supersonic flight paths were restricted to the ocean because of concerns about sonic boom on the ground. But just how loud was this boom? Was it ...
19
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2answers
1k views

How do turbofan nacelle lengths compare?

For example, compare the JT9D and the PW4000 below (both from Pratt & Whitney, both on a 747): (Left, Right) The PW4000 has a longer forward nacelle, and a covered exhaust cone. On the inside—...
21
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4answers
7k views

Are seaplanes allowed to taxi in residential areas?

There's a small pond/lake behind my house. A sea plane was just going around it. It was very loud and got like 10 feet from the shore. It's just going in circles and won't take off and leave. This is ...
0
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1answer
361 views

How does a normal aircraft exhaust nozzle (the base model) generates a lot noise? [duplicate]

How does a normal aircraft exhaust nozzle (base model) generates noise and, whats the difference between the operation of the normal base model of aircraft exhaust nozzle and the new design of ...
2
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1answer
453 views

Which type of chevrons is applied on the B787?

Which type of chevron nozzle was applied on the B787? I'm really confused about whether if it's sawtooth or sine wave.
1
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0answers
543 views

Why Planes Don't Fly Faster? [duplicate]

I recently Stumbled on this Why Planes Don't Fly Faster on youtube and it talked about how less speed is more economical for airlines and he also said something that plane above and below speed of ...
11
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4answers
1k views

Can an experienced airplane spotter identify planes only by sound?

I come from a background in railroad watching, and often times one can identify the maker of a railroad locomotive purely by sound. Maybe not the exact model of locomotive, but at least what type of ...
3
votes
1answer
671 views

What is the definition of “Sideline” in reference to aircraft noise?

The FAA has measured external aircraft noise levels and published the results in the Advisory Circular: AC 36-1H - Noise Levels for U.S. Certificated and Foreign Aircraft In the appendices, noise ...