Posts about: "RAT (Deployment)" [Posts: 361 Pages: 19]

Screamliner
2025-06-15T15:11:00
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Post: 11902541
I'm reading a lot of the comments, speculation is something we all like, but some things just do not add up, even with a RAT deployed

if they had dual engine failure around 50 feet where you raise the gear, how can they still find the energy to climb, since they would be at VR/V2 speed (not V2+20 at that altitude, what VNAV would command after take off, especially with a take off weight of around 205/210 tons, the 787 wings are amazing but not miracles

if they had a normal departure, why did they not raise the gear, they had a positive rate since they were climbing and the speed according to ADS-B was a constant. if they were single engine ! this would have saved them with this weight and weather, one of the first things you learn when EFATO with a 787, raise the gear, your climb performance increases dramatically

Intersection take off can be ruled out:
if they did an intersection departure with they're genex 64-70K engines, they would have had a take off limited weight of around 172 tons, I estimate that they were close to 205/210 tons, (max zfw of around 161 tons and around 45/50 tons of fuel) even full length would have been a stress for the engines, with the prevailing weather conditions, they would have never made it, full length is already difficult.


When we see the video, the airplane is still climbing / flying straight and level (not losing altitude), yet we hear what we think might be the RAT, I can't imagine that they had the kinetic energy to do this with no engines. if they had dual engine failure, they would have been a brick, Hot and High, no thrust, flaps 5, zero chance.

flickering of lights etc. seen by the survivor and the loud bang heard, I would not trust pax observations, because of the things they had to go through, also and I've said this before, if it was a loud bang, where is the smoke and fire in the engines, or in the video, its not audible

lets see what the report will say, but it it could be a lot to swallow for some

Last edited by T28B; 15th Jun 2025 at 16:30 . Reason: cleaned up formatting

1 user liked this post.

triumph120
2025-06-15T16:52:00
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Post: 11902628
Retired aircraft engineer here, mostly military experience. Way back in this thread a contributor stated that he/she had heard the noise the RAT makes many times because Boeing regularly tested it in flight on production aircraft near to where they lived. Can someone tell us how the RAT is tested in flight? Is there a switch to manually deploy the RAT and. if so, could the RAT have been deployed by the crew in this way?
StuntPilot
2025-06-15T17:09:00
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Post: 11902641
Originally Posted by Gino230
So it seems (after hours of reading), that the Almighty Prune has split into 3 camps, with each camp ignoring at least some evidence to the contrary, including that from actual experienced 787 pilots, test pilots, and engineers.

1. Incorrect flap / thrust settings / performance data / Autopilot management / general pilot error
2. Immediate, simultaneous thrust loss in both engines shortly after rotation
3. Crazy electrical / mechanical "theories" based on nonsense

My head hurts.
After hours of reading I conclude that so far nobody has the slightest clue about what happened.
1: Flaps were down
2: The RAT story is based on a single unsharp video frame. Earlier frames were much sharper but the RAT could not be seen (although there was a sound).
3. Lack of evidence

I could be wrong, in that case please link QUALITY evidence so that we can learn something new.
This way thousands of people are wasting countless hours.


6 users liked this post.

sorvad
2025-06-15T17:19:00
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Post: 11902647
Originally Posted by StuntPilot
After hours of reading I conclude that so far nobody has the slightest clue about what happened.
1: Flaps were down
2: The RAT story is based on a single unsharp video frame. Earlier frames were much sharper but the RAT could not be seen (although there was a sound).
3. Lack of evidence

I could be wrong, in that case please link QUALITY evidence so that we can learn something new.
This way thousands of people are wasting countless hours.
Visual evidence the rat was deployed, audio evidence the rat was deployed, evidence the APU inlet door was open, evidence the gear retraction was interrupted, evidence there was very little engine noise after departure, very obvious evidence that the aeroplane didn’t have enough thrust to stop it descending into the ground. All of this strongly suggests that both engines were to all intents and purposes, and for want of a better word, ‘failed’ now that could be intentional, accidental or because of some sort of technical malfunction or external factor. Nothing conclusive and no answers as to how or why, but not quite as wildly stabbing in the dark as your post would infer.

Last edited by sorvad; 15th Jun 2025 at 17:35 .

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StuntPilot
2025-06-15T18:15:00
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Post: 11902683
Originally Posted by sorvad
Visual evidence the rat was deployed, audio evidence the rat was deployed, evidence the APU inlet door was open, evidence the gear retraction was interrupted, evidence there was very little engine noise after departure, very obvious evidence that the aeroplane didn\x92t have enough thrust to stop it descending into the ground. All of this strongly suggests that both engines were to all intents and purposes, and for want of a better word, \x91failed\x92 now that could be intentional, accidental or because of some sort of technical malfunction or external factor. Nothing conclusive and no answers as to how or why, but not quite as wildly stabbing in the dark as your post would infer.
We agree that there was a lack of thrust. Possibly caused by a dual engine failure. But the sharpest frames in the video do NOT show the RAT and this is counter evidence to the RAT theory. If there were substantial technical failures who knows what sounds could be generated. I find the evidence weak at best. And we immediately get into a chicken-egg problem: did some power issue of unknown nature cause an engine failure or did a dual engine failure occur, resulting in a power loss? Both are extremely unlikely and need to be backed by quality evidence. The video is not it, in my opinion. I don't know the APU intake mechanism and whether it could open after the impact.

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Kraftstoffvondesibel
2025-06-15T18:25:00
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Post: 11902693
I realise the discussion has largely moved on, but for completeness I have analysed, filtered and compared the audio from several 787 videos\x97both take-off and landing (the latter with and without RAT deployment; take-off footage with the RAT out is rare).

Using the same style of frequency plots employed in the RAT analysis\x97and drawing on speed of different engine components data supplied by other contributors\x97it is straightforward to identify the engines\x92 high-power acoustic signatures objectively, despite variations among clips and the presence of Doppler shift.

What is clear is that the engine noise in the recording bears no resemblance to a typical 787 take-off profile. Whether the engines were merely at very low thrust/idle or fully windmilling I cannot say with certainty, but they were certainly nowhere near take-off power.

Make of that what you will.

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fdr
2025-06-15T18:58:00
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Post: 11902721
Originally Posted by matiagr
The biggest news site in Greece claims to have the results of a kind of preliminary report from India AAIB which say that as the plane rotated, the pilot's seat malfunctioned (broken pin) and went suddenly far back forcing the captain to accidentally lower the thrust lever as he already had his hand on it and despite the co-pilots effort to help increase the thrust it was already to late to avoid the stall. I dont believe they would have posted something as serious as this without any credible source cause they are supposed to be a serious news outlet but you never know when stupidity takes over validity. Source is the protothema dot gr site
I will wager that this is absolute nonsense. The effect of pulling the power levers back to idle at rotate would be readily countered by pushing them back up again. The engines are still delivering thrust, it is a function of N1, not the lever. The lever commands where the thrust level will end up, the N1 gives the thrust output. The acceleration/thrust characteristics of these engines is not like a J52 or JT3D etc.

The proposition that is floated is that the pilot does not pull back on the control column, which he is holding onto with both hands as his seat slides backwards like a caricature of a bad Cessna 180 seat rail, that is plainly obvious from the pitch attitude of the aircraft, yet grabs lustily a double handful of thrust levers and holds onto those until meeting Ganesh in the next life?

Greek papers appear to be as rigorous and incisive in their cognition as the Daily Telegraph. Golly.

Seats: electric.
RAT deployment... presumably the hapless pilot doesn't grab the control column, or the thrust levers, just grabs both fuel control switches instead????

Do any reporters bother to read what they write?

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njc
2025-06-15T19:03:00
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Post: 11902726
Originally Posted by tdracer
The 'good' news is that even a cursory check of the FDR will indicate if TCMA activated, so we'll soon know.
The investigators will certainly soon know, but how sure are you that they'll share that in public?

Originally Posted by Screamliner
So one thing to keep in mind, the RAT can be deployed manually, but also comes automatically when certain conditions arise, everybody here is assuming it\x92s only on dual engine failure but there are 4 more conditions that trigger the RAT
Nope, you may not have read the whole thread - the full set of conditions which can trigger the RAT have been posted multiple times before your reply

Originally Posted by Stivo
Am I understanding that you are saying that the noise on the video identified as a RAT has a Doppler shift that matches plausible values for height and speed? That seems pretty conclusive to me that it is a RAT.
I'd phrase it differently: the frequency (and harmonics) of the noise are consistent with it being a RAT. If you then assume that it was a RAT and infer distance and speed curves from the Doppler variation, you get plausible values for an aircraft. But the two things are somewhat linked so you can't really treat the second thing as confirmation of the first. (FWIW, I'm personally quite satisfied that it was indeed a RAT on the audio.)

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sorvad
2025-06-15T19:15:00
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Post: 11902740
Originally Posted by StuntPilot
We agree that there was a lack of thrust. Possibly caused by a dual engine failure. But the sharpest frames in the video do NOT show the RAT and this is counter evidence to the RAT theory. If there were substantial technical failures who knows what sounds could be generated. I find the evidence weak at best. And we immediately get into a chicken-egg problem: did some power issue of unknown nature cause an engine failure or did a dual engine failure occur, resulting in a power loss? Both are extremely unlikely and need to be backed by quality evidence. The video is not it, in my opinion. I don't know the APU intake mechanism and whether it could open after the impact.


Stivo
2025-06-15T19:23:00
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Post: 11902745
Originally Posted by fdr
I will wager that this is absolute nonsense. The effect of pulling the power levers back to idle at rotate would be readily countered by pushing them back up again. The engines are still delivering thrust, it is a function of N1, not the lever. The lever commands where the thrust level will end up, the N1 gives the thrust output. The acceleration/thrust characteristics of these engines is not like a J52 or JT3D etc.

The proposition that is floated is that the pilot does not pull back on the control column, which he is holding onto with both hands as his seat slides backwards like a caricature of a bad Cessna 180 seat rail, that is plainly obvious from the pitch attitude of the aircraft, yet grabs lustily a double handful of thrust levers and holds onto those until meeting Ganesh in the next life?

Greek papers appear to be as rigorous and incisive in their cognition as the Daily Telegraph. Golly.

Seats: electric.
RAT deployment... presumably the hapless pilot doesn't grab the control column, or the thrust levers, just grabs both fuel control switches instead????

Do any reporters bother to read what they write?
I think it\x92s made up nonsense, but it is at least worth noting that pulling back to idle and pushing back with the wheels still on the ground is a potential TCMA trigger.

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limahotel
2025-06-15T19:24:00
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Post: 11902747
Originally Posted by matiagr
The biggest news site in Greece claims to have the results of a kind of preliminary report from India AAIB which say that as the plane rotated, the pilot's seat malfunctioned (broken pin) and went suddenly far back forcing the captain to accidentally lower the thrust lever as he already had his hand on it and despite the co-pilots effort to help increase the thrust it was already to late to avoid the stall. I dont believe they would have posted something as serious as this without any credible source cause they are supposed to be a serious news outlet but you never know when stupidity takes over validity. Source is the protothema dot gr site
I saw the comment stating the above on AHerald (giving a detailed timeline of events). But why would the captain keep his hand on thrust levers at Vr? Also, can electrically adjustable seats suddenly just slide backwards? Additionally, this doesn't account for the RAT deployment. If they had truly firewalled the throttles afterward, we would expect to see a pitch-up moment\x97which isn\x92t evident in the video (at least to me). Perhaps a nose-down trim could have counteracted it, but that seems like a bit of a stretch.

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DIBO
2025-06-15T19:29:00
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Post: 11902749
But the sharpest frames in the video do NOT show the RAT and this is counter evidence to the RAT theory.
After hours of reading I conclude that so far nobody has the slightest clue about what happened.
1: ...
2: The RAT story is based on a single unsharp video frame. Earlier frames were much sharper but the RAT could not be seen (although there was a sound).
3. ...
I could be wrong, in that case please link QUALITY evidence so that we can learn something new.
This way thousands of people are wasting countless hours.
I've been sitting on my hands for days now...but please stop linking RAT deployment evidence with some blurry cluster of pixelation, which proves nothing.
This Pprune-forensic audio analysis (and subsequent posts) by Kraftstoffvondesibel, although completely ignored by many it seems, is the only clear proof there was a deployed RAT sound recorded in the young boy's video clip. You may disprove the analysis as much as you like, but referring to blurry video regarding possible RAT deployment or not, is indeed " thousands of people are wasting countless hours "

Originally Posted by Kraftstoffvondesibel
I realise the discussion has largely moved on, but
I'm rather under the impression that many recent discussions are going backwards or h amsterwheeling.
But thank you for your valuable audio analysis


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sorvad
2025-06-15T19:34:00
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Post: 11902757
Originally Posted by DIBO
I've been sitting on my hands for days now...but please stop linking RAT deployment evidence with some blurry cluster of pixelation, which proves nothing.
This Pprune-forensic audio analysis (and subsequent posts) by Kraftstoffvondesibel, although completely ignored by many it seems, is the only clear proof there was a deployed RAT sound recorded in the young boy's video clip. You may disprove the analysis as much as you like, but referring to blurry video regarding possible RAT deployment or not, is indeed " thousands of people are wasting countless hours "

I'm rather under the impression that many recent discussions are going backwards or h amsterwheeling.
But thank you for your valuable audio analysis
If you’ve read the whole thread, you’ll see that most of us who are acknowledging rat evidence are also citing this compelling audio evidence too.

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Alty7x7
2025-06-15T20:23:00
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Post: 11902791
Engine failure with electrical power loss

Originally Posted by StuntPilot
We agree that there was a lack of thrust. Possibly caused by a dual engine failure. But the sharpest frames in the video do NOT show the RAT and this is counter evidence to the RAT theory. If there were substantial technical failures who knows what sounds could be generated. I find the evidence weak at best. And we immediately get into a chicken-egg problem: did some power issue of unknown nature cause an engine failure or did a dual engine failure occur, resulting in a power loss? Both are extremely unlikely and need to be backed by quality evidence. The video is not it, in my opinion. I don't know the APU intake mechanism and whether it could open after the impact.
To simplify the chicken/egg:

Tdracer earlier confirmed that an airplane electrical power loss would allow engines to keep running , because 1) engines are fully-capable of suction feed operation in takeoff envelope (if boost pumps lost), and 2) the EECs are powered by their own PMAs when running and to substantially below idle (I recall roughly 10% N2). Airplane powers the EEC for ground starts, prior to PMA coming online, and as backup to the PMA after that.

Related:

Engine igniters are powered by the aircraft. So theoretical full loss of aircraft power would disable Autorelight upon a flameout. Ignitors typically don't make the cut for most-essential battery-only loads because it would also take an engine flameout, and the airplane past V1 in ground roll can fly fine on one engine that can achieve takeoff thrust.

Autorelight is relevant - if there was a single-engine failure post V1, autorelight will attempt to relight the engine, so there is no need for a pilot to try to cycle the fuel switch to reset the EEC (potentially grabbing the wrong one), or to otherwise intervene. In such a circumstance, they need to trust their training. I've heard accounts that the most likely pilot instinct in such a situation would be to push the throttle(s) forward.

Finally - there was talk earlier about accidentally cutting the fuel switches - and it was duly noted that they have to be pulled out over the detent, so very unlikely. The same cutoff effect could be achieved with the engine fire handle(s), right behind the fuel switches on the pedestal - though they are an upward pull, so also not subject to inadvertent or accidental engagement.
Compton3fox
2025-06-15T20:52:00
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Post: 11902822
Originally Posted by StuntPilot
After hours of reading I conclude that so far nobody has the slightest clue about what happened.
1: Flaps were down
2: The RAT story is based on a single unsharp video frame. Earlier frames were much sharper but the RAT could not be seen (although there was a sound).
3. Lack of evidence

I could be wrong, in that case please link QUALITY evidence so that we can learn something new.
This way thousands of people are wasting countless hours.
if you had read the whole thread, you would have seen ths 2 independent audio analysis of the HQ video soundtrack, comparing with 2 other segments. It has been established that with 99% certainly that the RAT was deployed. Not to mention the ear witness who has heard 500\xd7 RATs close to Boeing field

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Captain Fishy
2025-06-15T21:56:00
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Post: 11902882
Originally Posted by bakutteh
Do not discount the mistaken early flap retraction scenario too easily. Mull on this:

PF commanded gear up on attaining positive rate of climb, fixating on the HUD.
PM mistakenly raise flap lever from 5 to Flap 1 gate. Thrust reduced to Climb Thrust. Landing gear remained deployed. Massive loss of lift misidentified as loss of thrust. If any one pilot just had a dual engine failure scenario on a recent sim ride, brain and muscle memory would jump to loss of thrust in dual engine, prompting them to accomplish the recall memory items which called for both engine fuel control switches to CUTOFF and then RUN, and physically deployed the RAT.

There would be immediate loss of thrust with the engine taking time to recover , if at all, at such low airspeed!
The rest is left for Ppruners\x92 imagination.😖🥴😬

A loss of lift AND thrust at this critical juncture could have had caused this awful disaster. I think the data recorders have already revealed the cause but If it's this, then I don't think we will hear much anytime soon.
Kraftstoffvondesibel
2025-06-15T22:06:00
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Post: 11902890
Originally Posted by StuntPilot
If you would read my post carefully you would know that my issue is that at the moment that the RAT is claimed to be heard and the plane is close the RAT is not seen in the frames. That comes much later when the plane is far away and pixelated. There is no ear witness. There is someone who claims to have heard hundreds of RAT deployments (not 500) and who has heard the audio. So yes, there is a brief RAT-like sound. But the evidence is too weak to base elaborate theories on.
The audio analysis in this case isn't anything obscure or vague. The same software is used in courts all over the world every day. You can be pretty sure the same software in some iteration is used investigating CVRs all the time. It shows something emitting the exact same sonic signature as a B787 RAT went over the camera at the same speed as the Boeing 787 seen going over the camera. It isn't a broken fanblade, or a motorcycle passing by, that would give a completely different result. It literally means hundreds of thousands of datapoints fall into the exact same pattern. If it were anything else, that would be easy to observe. It is a much more accurate tool than watching heavily compressed video. It is the same software used in hollywood to surgically remove airplane noises from historical dramas, btw. At least until AI came along and took on that job about 2 years ago. . Just because you aren't familiar with it doesn't mean it isn't accurate.
Just putting this out there, since many might be unfamiliar with this, you included.

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DIBO
2025-06-15T22:27:00
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Post: 11902910
Originally Posted by The Ancient Geek
Lots of noise about RAT, gear doors, pilot seats, etc,etc,etc.
The RAT being deployed or not, is an essential factor.
But indeed, a lot of noise is being generated by some that continue to simply ignore the professional sound analysis provided already 600+ (surviving) posts ago, without any relevant counter-arguments or proof (other than some low quality video).

(And I don't mind this sound analysis to be proven invalid, but then only with similar professional skills and counter arguments.)

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First_Principal
2025-06-15T23:22:00
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Post: 11902953
Originally Posted by grumpyoldgeek
Firstly. I find all the speculation about hearing the RAT suspect...
Originally Posted by Kraftstoffvondesibel
The audio analysis in this case isn't anything obscure or vague....
Originally Posted by DIBO
... a lot of noise is being generated by some that continue to simply ignore the professional sound analysis provided already 600+ (surviving) posts ago ... And I don't mind this sound analysis to be proven invalid...
Originally Posted by StuntPilot
Maybe you should describe your analysis then and present the data? I'm a physicist so chances are I might actually not be so unfamiliar. Please include an analysis of raw data quality, spectral resolution and binning as well....
As one of the two authors who have offered an acoustic analysis of the AI 171 'RAT' video here I feel obliged to make some observations.

First of all Kraftstoffvondesibel and I did our work completely without knowledge of each other. We reached the same conclusions more or less, most likely using different software (I used four different methodologies) and in subsequent discussions between us we've found our specific results (frequency etc) match very closely - including the doppler shift that we've also both commented on.

While this doesn't absolutely prove the RAT scenario (I was, at least initially, somewhat more circumspect on this matter as anyone reading my first post would find) it does go some distance towards reconciling our respective methodologies and outcomes. Given the confluence and discussion I am now more satisfied that the RAT was deployed than I was before - although for the reasons espoused earlier I totally recognise the [scientific] challenges to this view.

In this regard I too would not 'mind' if our view regarding RAT deployment were proven incorrect. What Kraftstoffvondesibel and I have done is simply use a little science and apply a quantitative analysis to the available data that many had qualitatively argued over. One might hope that, amongst other things, it could have dispelled the RAT/no RAT question to some degree and reduce thread noise, but unfortunately it seems some haven't read the thread through, or perhaps lack analytical reasoning.

This site isn't the place for a full academic paper+peer review and for me the real subject of this thread is the tragedy of AI 171 and what might determinable from what we know in the hope it will be useful to those closer to the coal face. If you are a physicist, scientist or engineer and have the capability then the same data we used is also available to you to do your own analysis. Should you do so we'd welcome hearing the outcome - whether it concurs with our results or not - as this is the scientific way. If you want to include the full nitty-gritty detail of how you've gone about then for a very small percentage of us that might be interesting, but it'd be peripheral to the main issue - and bear in mind that RAT deployment itself is merely an indicator of other potentially more serious issues. It is not likely to be the cause per se !

To conclude, I understand it's a long thread but as far as the RAT question is concerned, I'd encourage you to read the relevant posts at least and if you remain unconvinced, and you have the skills, then why not conduct your own analysis and let us know the results? Otherwise perhaps as a group we could move on from this, remembering that this is a terrible event which at the very least deserves informed useful discussion rather than wild and/or repetitive speculation.

FP.

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Kraftstoffvondesibel
2025-06-15T23:36:00
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Post: 11902967
Originally Posted by StuntPilot
Maybe you should describe your analysis then and present the data? I'm a physicist so chances are I might actually not be so unfamiliar. Please include an analysis of raw data quality, spectral resolution and binning as well. And don't state it is the 'exact same' as this is statistically impossible.
I don't believe I owe you anything, I believe this is done adequately previously and has already taken up enough time on this thread. I am of the opinion that we have shown the RAT being deployed satisfactory enough to be of use for speculation in this thread. I find repeated comments about the bad video being the only evidence a bit disrespectful, though. Even from a mere physicist. It is based on a spectrogram over time. The source file shows audio up to about 16 kHz, it is unknown whether this limitation is in the file format (ie. 32kHz sampling rate) or microphone. Doesn't matter much. The frequencies above 16kHz is not important in this context as it is not where the sound energy is anyway. The audio will have been lossy data compressed, but it does not affect these prominent properties of the audio. It does make me hesitant to draw conclusions from the parts of the spectrum with more broadband noise and several intersecting sounds. Noise floor suggests 16 bit sampling depth. Spectral resolution? N/A All samples are included. The spectrogram covers the entire frequency range recorded, It shows comparatively the same overtones of the fundamental expected from the technical specifications of the 2 bladed RAT running at it's intended RPM, the doppler characteristics fits completely with a reasonable range of passing speeds and distance to the passing source plotted out. Compareatively, All the harmonics are identical both in pitch and seperation to a recording of a known B787 landing with RAT deployed, while the Doppler fall shows a longer time frame in the landing video taken from a further distance. As expected. The overtones easily discernable in this recording falls in the 220-2700Hz range. Below that, there is other noise centered around 150Hz, which gradually fades towards the end of the recording. This, as far as I can find in available information, fits with an idling or even windmilling B787 engine, but this is not conclusive. This falls in a range of the spectrum where there are other noise sources and the signal/noise is low and of a broader band characteristic, these masking frequencies is where the lossy data compression might play tricks, so I do not weigh that heavily. Recordings of landing B787 without the RAT, shows none off the same characteristics, and completely lack the tonal components and exact overtones shown with the RAT deployed. More importantly, compared to videos of B787s taking off with normal take off thrust, the latter shows distinct tonal elements, but with very different overtones,, both in separation and composition, again possible to relate to known quantities of the rotational speed and elements of the engine at high power. The AI recording shows none of this.

The latest techniques let us separate such things as reverbration from the source, when superimposing the reverberation/ambience and background noise of the AI crash urban environment on the clean, dead open field recording of the known B787 w/rat, they do indeed sound exactly the same to this very skilled and experienced listener. Although this is not courtesy of the computer analysis. It is just another angle of confirmation.

All in all, i think this source audio is excellent. The source is an iphone, their mems based microphones, although noisy shows great spectral balance and is comparable to basic measurement microphones of professional application. There is plenty of information to analyse from in this sample.

And again, I can't see it in the video either, and until I put on some really expensive headphones and fired up the software I was of a different opinion. I bowed to the science.

Edit: I took an extra look, I am prepared to say the fall off at slightly above 16kHz is from the original recording, this is probably a limitation in the microphone, as it is not a hard cut-off before a 16kHz Nyquist frequency as it would be with a 32kHz sampling rate, there is dither noise from 16-20kHz fitting with the source being 16 bit.

Last edited by Kraftstoffvondesibel; 15th Jun 2025 at 23:54 .

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