The Merlin Hum

[Vraciu]

I know awhile back we were discussing this and nobody understood what I meant when I spoke of The Merlin Hum.   

https://bbs.hitechcreations.com/smf/index.php/topic,393097.msg5220149.html#msg5220149

It is a very special sound that audio equipment can't pick up quite the way your ears do.  It's a kind of descending, thrumming, hum with just a touch of Doppler Effect to it.

Well, I found a video that captures about 90% of the sound.   When you hear it in real life you are never the same again.   It gives you goose bumps.


https://youtu.be/NFBaBZjOh7s?si=veP0YFW1gaH4roZN

The sequence is at 0:40, the hum is 0:47-0:48 before the exhaust crackle and whistling blanket it.


https://youtu.be/NFBaBZjOh7s?si=veP0YFW1gaH4roZN

[Baloo]

Th p38 sounds Challenge was using are awesome...wish it didn't have the errors though

[Animl-AW]

The distinctive whistling sound heard from a P-51 Mustang is caused by the airflow over the gunports, specifically the gun ejectors on the underside of the wings.  This is an external sound. Its generally created at certain speeds and angle of airflow. It can come and go.

The only way to isolation it and triggered is to make a synthetic sound and layer it in. But it might need a speed triggered to be proper

That could be a hard, but not impossible, to record a real one that can form a loop. It has to make a steady loop. Most recording would be fade in fade out because they are always passing.

IF I take up FMOD , that would be my first project to defeat. Single planes can be done. Its def a challenge, no pun intended. Find a 3 sec steady sound and its worth looking into. If I can isolate it.

[Vraciu]

I'm not talking about the whistle though, which I don't like.   (The whistle is actually blocking it along with the exhaust at 0:49).

I'm talking about the hum.   This usually gets blanked out by either the whistle or the exhaust (in this case by both).   It's a unique sound that you don't fully hear on recordings and don't always hear in real life.    I think the closure rate has a lot to do with it.

But they caught a bit of it here.

I grew up listening to this sound and it never gets old.   When you hear it you feel like you won the lottery, it's that special.  And again,  it is not the whistle or the crackle.   It's a descending thrumming hum not a screech.

[Animl-AW]

I'm not talking about the whistle though, which I don't like.   (The whistle is actually blocking it along with the exhaust at 0:49).

I'm talking about the hum.   This usually gets blanked out by either the whistle or the exhaust (in this case by both).   It's a unique sound that you don't fully hear on recordings and don't always hear in real life.    I think the closure rate has a lot to do with it.

But they caught a bit of it here.

I grew up listening to this sound and it never gets old.   When you hear it you feel like you won the lottery, it's that special.  And again,  it is not the whistle or the crackle.   It's a descending thrumming hum not a screech.

Oh that may be easy buy boosting 125hz to 300hz on the EQing, peak arch seems to be around 200-220ish. It would be an arch of the freqs, maybe only 2-3db boost at the peak of the arch. In that slice of time you're just hearing the engine itself, the exhaust and whistle is not pointed directly at your ear. As the plane passes the whistle is point at you...after it passes the exhaust is pointed at your ear. SO yes, this is PROBABLY doable.

[Animl-AW]

[ Invalid YouTube link ]

an old lamer beginner vid I made.

Listen to the 51 at 4:41 and 5:24, 7:24, imagine that sound with the 125 > 220hz > 300 peak boost. I think that would fill the gap you're talking about.
That said, if I worked o it at all it would be putting that whistle in there, like it or not, it's a characteristic. It's either authentic or it's not.

[Vraciu]

The whistle is overdone in all recordings.  In real life audio equipment grabs that but your ear doesn't.

The hum is masked by technology not physics.   Fifty years of listening to Mustangs, FWIW...

(I'll take a look at that later when I have better speakers than my phone.)

[Animl-AW]

I’ll make a video and EQ it and you tell me if it sounds right. Many times someone EQed never heard the real thing enough. If I nail it I’ll know exactly what I need to do in FMOD, when I get to it.

[xanax]

The sequence is at 0:40, the hum is 0:47-0:48 before the exhaust crackle and whistling blanket it.

Yeah, it's a low-end "warbling" sound to my un-trained ear and vocabulary. It instantly brings back memories from the Reno Air Races. It's quite distinct and sounds really cool. You hear it right on the marks you suggest before the howl/whistle overtakes it.

"Merlin Hum"..... I walked through a renaissance faire once and saw a dude wearing robes and wizard hat chanting out loud while waiving a chopstick. I really had to fight the urge to give him an Arthurian legend wedgie, snap his chopstick and shove him into a mud puddle. I think he too was doing a "Merlin Hum." Nerd!

[Vraciu]

I’ll make a video and EQ it and you tell me if it sounds right. Many times someone EQed never heard the real thing enough. If I nail it I’ll know exactly what I need to do in FMOD, when I get to it.

Will do.  Looks like Xanax can help, too.

[Vraciu]

Yeah, it's a low-end "warbling" sound to my un-trained ear and vocabulary. It instantly brings back memories from the Reno Air Races. It's quite distinct and sounds really cool. You hear it right on the marks you suggest before the howl/whistle overtakes it.

"Merlin Hum"..... I walked through a renaissance faire once and saw a dude wearing robes and wizard hat chanting out loud while waiving a chopstick. I really had to fight the urge to give him an Arthurian legend wedgie, snap his chopstick and shove him into a mud puddle. I think he too was doing a "Merlin Hum." Nerd!

 

[Animl-AW]

Keep in mind, if p51 gun ports were removed the 51 will not whistle.

I hit the proper frqs. But its still too smooth. You might only get that growl when the plane pulls up?

Also, physics do apply in all things audio. Recording sound at airshows and airports, If its over concrete, higher freqs will be exaggerate, hence masking the growl. Concrete and buildings are very reflective.

Only real way to do it right is over grassy field.

[Vraciu]

I've watched Mustangs fly in every conceivable configuration.  Gun ports.  No gun ports.  Taped gun ports.  Two seats.  One seat.  Cavalier conversions.  Desert.  Grass.  Concrete.  Bs.  Cs.  Ds.  Ks.   Cuffed props.  Uncuffed.

It's recording tech (noise reduction/protection?) more than any other factor that masks the hum.   Films from the 70s actually do a better job than 99.9% of what we see today.

I've even seen multiple film of the same air show from identical locations (or from the other end of the field), like this one, and all of them sound different, with only one catching the hum.

It's the mic not the terrain.    The sound wave propagates in all directions.   Grass is not making any audible difference to the human ear.

Old Red Nose is making the hum at 0:07 but the mic is not good enough to fully capture it.   On the second pass it doesn't catch it at all.   But your ear hears it fine.

https://youtu.be/Ga53BtyIUt4?si=semJX9Yp1uKbGZnq




Here again at 0:40, 1:51, 3:09, 3:50, and 3:58, the hum is being generated but the mic is grabbing the noise around it instead or it's being blanked by noise filtering.

https://youtu.be/1xrWUlDyUUs?si=ZsxgAicNCfQ0RNjo