The Merlin Hum

[Vraciu]

Dude, you are talking to a 45 yr experience sound engineer. You are wrong on several levels. Sound is 100% physics. Everything affects it. The reason you can even hear sound waves is because of air and physics. No air, no sound. Every surface can change it. Humidity in the air can slow the vibrations you gear.. temperature affects sound. Buildings and glass will absolutely change it. Any reflective surface can change it. The only way to avoid it is in a field of nothing but grass, even grass can affect it dissolving frequencies. We haven’t even touched hiow different mic diaphragms will absolutely change it.

And you're talking to a guy that has more time listening to Merlins in his sleep than you have while awake.  53+ years.   I grew up with them, which is part of the reason I'm the only one on this board that even knows what sound we're talking about here.

Grass and concrete have zero impact on when/if you hear the hum in its full glory.   It can be heard at any temperature, on any surface, and in every level of humidity from the sticky sea level ocean air of Harlingen to the arid high desert sky of Reno.

Most mics do a terrible job replicating the human ear.   Noise filters, mic covers, composition of the mic itself, etc. all play a role in screwing this up.

You can hear it on one pass in still air and not hear it with a subsequent pass from the exact same direction.   Then hear it again from the same or different direction later--or not.   Mics will pick up the sound 1% of the time at most, even when your ear hears it clearly.    That's an equipment issue not a humidity/surface composition issue.

Airspeed, groundspeed and RPM are the three main factors that impact one's ability to hear the sound*, not humidity, grass, or concrete.  These factors are not even rounding errors.

--
*Doppler Effect also has to play a role if I had to guess.

[Animl-AW]

And you're talking to a guy that has more time listening to Merlins in his sleep than you have while awake.  53+ years.   I grew up with them, which is part of the reason I'm the only one on this board that even knows what sound we're talking about here.

Grass and concrete have zero impact on when/if you hear the hum in its full glory.   It can be heard at any temperature, on any surface, and in every level of humidity from the sticky sea level ocean air of Harlingen to the arid high desert sky of Reno.

Most mics do a terrible job replicating the human ear.   Noise filters, mic covers, composition of the mic itself, etc. all play a role in screwing this up.

You can hear it on one pass in still air and not hear it with a subsequent pass from the exact same direction.   Then hear it again from the same or different direction later--or not.   Mics will pick up the sound 1% of the time at most, even when your ear hears it clearly.    That's an equipment issue not a humidity/surface composition issue.

Airspeed, groundspeed and RPM are the three main factors that impact one's ability to hear the sound*, not humidity, grass, or concrete.  These factors are not even rounding errors.

--
*Doppler Effect also has to play a role if I had to guess.

Don’t attempt to teach me about audio and the physics of it. You clearly do not understand it. Audio is 100% physics. Stay in your lane

I have heard mic pick up what you are explaining.

The right mic will pick up 20hz to 20khz
The human ear can’t hear that whole spectrum.
You are lucky to hear below 30hz or above 10khz

Human hearing damage begins at birth
A mic never has hearing damage
No two humans hear exactly alike. The same with mics, even if the same model

The higher the freq in a sound the more directional it is
Lower freq in a sound the more omni directional it is

The whistle comes from gun ports facing forward
The growl comes from exhaust facing rear
Air passing over surfaces can create sound too.

Reflective surfaces matter in a clean pure recording of exterior sounds.

This is fact and physics
Physics is math, its absolute
Without air sound may not exist
In space scream all you want, it won’t be heard

[Dadtallica]

This will be LOL I’m in! 

[Vraciu]

Don’t attempt to teach me about audio and the physics of it. You clearly do not understand it. Audio is 100% physics. Stay in your lane

I have heard mic pick up what you are explaining.

The right mic will pick up 20hz to 20khz
The human ear can’t hear that whole spectrum.
You are lucky to hear below 30hz or above 10khz

Human hearing damage begins at birth
A mic never has hearing damage
No two humans hear exactly alike. The same with mics, even if the same model

The higher the freq in a sound the more directional it is
Lower freq in a sound the more omni directional it is

The whistle comes from gun ports facing forward
The growl comes from exhaust facing rear
Air passing over surfaces can create sound too.

Reflective surfaces matter in a clean pure recording of exterior sounds.

This is fact and physics
Physics is math, its absolute
Without air sound may not exist
In space scream all you want, it won’t be heard

Wow, such searing commentary--and yet completely wrong.  Mostly just TLDR.   

Mics SOMETIMES pick it up, otherwise the examples I posted wouldn't exist, "sound engineer" (LOL). Unfortunately,  99% OF THE TIME THEY DO NOT.

Your theoretical classroom nonsense doesn't apply to what happens in real life.    I've witnessed it repeatedly for five decades.

We're not talking about whistles and exhaust.   We're taking about a (Doppler?) hum that is so distinct yet subtle you with all your alleged experience have no clue what it is.  My wife can hear it.  My kids can hear it.  Anyone who knows what to listen for can hear it.   But you,  our resident "sound engineer" (HA HA HA) can't (double HA HA HA).

If anyone needs to stay in their lane it's you--your preferred method, apparently, is in the middle of the stripe going the wrong way.  I had more aviation experience by the time I was five than you ever will in two lifetimes.   Harass/stalk someone else.   You bore me.

/Discussion

[Animl-AW]

Wow, such cearing commentary--and yet completely wrong.  Mostly just TLDR.   

Mics SOMETIMES pick it up, otherwise the examples I posted wouldn't exist, "mister soind engineer" (LOL). Unfortunately,  99% OF THE TIME THEY DO NOT.

Your theoretical classroom nonsense doesn't apply to what happens in real life.    I've witnessed it repeatedly for five decades.

We're not talking about whistles and exhaust.   We're taking about a (Doppler?) hum that is so distinct yet subtle you with all your alleged experience have no clue what it is.  My wife can hear it.  My kids can hear it.  Anyone who knows what to listen for can hear it.   But you,  our resident "sound engineer" (HA HA HA) can't (double HA HA HA).

If anyone needs to stay in their lane it's you--your preferred method, apparently,  is in the middle of the stripe going the wrong way.   I had more aviation experience by the time I was five than you ever will in two lifetimes.   Harass/stalk someone else.   You bore me.

/Discussion

Listen Doxxer law breake, you broke more laws than I did. I should iwn your house. So shut it
After what you did to me I deserve a gold metal for gaving more than inr word with you.

Figure it out, you’re on your own.

Dunning-Kruger Effect is in epic proportions

Maybe a pen*s extension will solve your problems

[Vraciu]

*Yawn*

[Animl-AW]

Doxing isn't always a standalone crime but becomes illegal when it crosses into existing laws like stalking,
harassment, threats, or identity theft; however, some states (like CA, IL, AL) are creating specific doxing laws, and it's a federal offense to dox government employees due to national security, often prosecuted under related offenses with potential jail time, fines, and civil penalties.
When Doxing Becomes Illegal

    Intent to Harm: If done with intent to threaten, harass, intimidate, or incite violence, it can lead to prosecution for those specific crimes.
    Stalking/Harassment: Sharing info to cause distress or fear falls under cyberstalking or harassment laws.
    Identity Theft: Using personal info (like SSNs) for fraud is illegal.
    Threats: If the shared info leads to threats of serious bodily harm, it's a crime.

Federal & State Laws

    Federal Offense: Doxing government employees is a federal crime.
    Evolving Laws: Some states, like California, Illinois, and Alabama, have specific anti-doxing statutes, allowing civil suits or criminal charges. Colorado also has laws targeting doxing with potential threats.

Why It's Tricky

    Publicly Available Info: Doxing often uses information already online, making prosecution difficult unless intent to harm is proven.
    First Amendment: Laws must be carefully crafted to avoid infringing on free speech, often requiring proof of harmful intent.

In Summary: While publishing public info isn't inherently illegal, doxing becomes criminal when it enables stalking, harassment, threats, or identity theft, with specific state and federal laws increasingly targeting it.


https://www.flatriallaw.com/blog/2021/10/what-is-doxing-and-how-can-it-get-you-in-trouble-with-the-law/

I've done sound for 7 presidents with all the clearances. I'm considered a gov employee. Your information can be subpoenaed and your devices seized as evidence, it's SOP for internet crimes. You have been informed

[Vraciu]

The Secret Service wouldn't let you anywhere near a President. 

Like I told you before, come and get me, tough guy!

[Vraciu]

What do Animal-AW and an SU-57 have in common?

...


 

[icepac]

I grew up going to and later crewing at unlimited hydroplane events.   

I was there when Skipp Walther had his fatal crash and have heard all manner of merlins, Allison’s, and griffons.   
I also skipped school a few days earlier and saw Jim Mccormick get cut up badly in the same boat. 

In hydroplane racing a merlin sounded nothing like what you hear when a P51 does a fast pass. 

The boats have a sound like a large truck climbing a dirt road while losing and regaining traction as they pass but were so loud, I could hear them from my house on Key Biscayne or from my classroom at George Washington Carver Jr. high.   

Every merlin I have heard in a flying plane sounds different from each other to me likely because of the plane shape, amount of prop blades, type of exhaust extractors, and the speed of the flyby…..along with many contributions of sounds that the merlin is not responsible for.

[Dadtallica]

I loved those Hydro races as a kid! I got to sit in the miss Budweiser once and I was the best day ever!

[Vraciu]

Every merlin I have heard in a flying plane sounds different from each other to me likely because of the plane shape, amount of prop blades, type of exhaust extractors, and the speed of the flyby…..along with many contributions of sounds that the merlin is not responsible for.

That said,  gun ports do not contribute to the sound.   They mask it.

One notable example being "Old Red Nose" down in Harlingen when it had faired over gun ports like most Mustangs did way back in the day.  It has gun ports now.   The hum was always there regardless of configuration.  The whistle and shriek hides the hum it doesn't contribute to it. 

[icepac]

I do know that strega and voodoo sound different and long ago you could tell which ratio gearcase they were running by the sound....and rpms.

I bet this sounds different. 

[Vraciu]

I do know that strega and voodoo sound different and long ago you could tell which ratio gearcase they were running by the sound....and rpms.

I bet this sounds different. 

(Image removed from quote.)

Haven't heard those two in a long time but my recollection is they had really loud exhaust.   But they're also pumping almost double the horsepower of the standard Merlin.   I also believe the prop tips are supersonic when they're going full bore.   Hard to hear much of anything when that happens.   BT-15s, etc. are loud for that reason, too.

Yeah the extra blades on the G could make a difference.   Guess we'll never know.

[LCADolby]

Fk me is Animl in here causing chaos as well... That guy could argue over pain drying.