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Directing extras in the 1922 silent film Robin Hood. That's director Allen Dwan on the far right in the hat, and I think that's the lead Douglas Fairbanks standing at the middle of the megaphone. Microphone technology had been invented by 1922, but I believe it was not yet as effective as a simple giant cone. This makes me curious about the limits of using a megaphone to amplify sound.
https://s3-us-west-1.amazonaws.com/h..._megaphone.jpg
Is that where the term he has a loud mouth came from
I design loudspeakers amd horns in particular for a living. A good horn with proper coupling can multiply the sound level by 12 times.
Not 100% on the quality of the coupling in the throat of the conical horn here. But the throat is large enough to push your face against so should be decent coupling.
Is there a specified ratio of length to diameter? Would a longer but narrower horn project sound further?Quote:
Originally Posted by mwmkravchenko
There are balances. A horns length dictates how low it can support the sound. The size of the mouth ( large end) really dictates how ripple free the sound will be. Ripple as in not exactly like the sound input but rather a bit distorted.Quote:
Originally Posted by 12bolts
If you are interested there is a great program for designing horns that is free:
Hornresp
And a huge thread on how it works : Hornresp - diyAudio
There is a pretty comprehensive manual built into the program.
Sound projection is more a situation of the correct length to mouth diameter for the frequency range that you are interested in. Human voice is a fairly narrow bandwidth and not that hard to do right.
A horn is actually an acoustical transformer. It increases the efficiency of coupling of the impedance of the small mouth (relative to the wavelength of vocal frequencies) to the surrounding atmosphere. It does not "amplify" the vocal power output which is in the microwatt range before and after passing through the horn. By enhancing the coupling efficiency it facilitates projection of the main part of the vocal frequency range. The main frequency range for vocal communication is from about 500 Hz to 3kHz. The wavelength of sound in air is roughly 1 foot at 1kHz.
The other phenomenon exploited by the horn is increasing the directionality of the projected voice. As the outlet aperture of the horn increases, the directionality of the projected voice narrows into a sharper beam.
Decades ago I fabricated a parabolic microphone reflector about 1 meter in diameter to identify sound sources in refineries from overlooking hills for our acoustical consultation practice. Testing the directionality by rotating the microphone and reflector in front of a sound source in an open field, we found that the directionality was very sharp in the multi-kHz range but essentially zero below 1 kHz. Directionality is directly related to "gain" relative to the bare microphone. (Our reflector was used for decades by Yosemite rescue personnel to communicate with climbers stranded on rock faces.)
The conical horn shown in the poster's photo is very inefficient, acoustically. Far more efficient is an exponential flare with the rate of flare directly influencing the lowest frequency that can be propagated efficiently through the horn (and the diameter of the mouth influencing the efficiency of coupling of the low frequencies to the air). That is the reason for the familiar graceful curved appearance of horns on everything from truck and train horns to civil defense alarm horns. Most of the science of horn acoustics was developed subsequent to the use of the simple conical horn shown in the silent movie set.
awright
Did anyone else get the pun - silent films?
As i have a big mouth do i only need a small cone.
Ingmar Bergman directs The Devil's Eye in 1960. The twirling circular tool on the left is used to cast shadows of foliage across the driver's face, to give the illusion of motion.
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Buster Keaton stunt.
This is (one of) the great things about older films: you get to experience genuine curiosity/wonder/awe when considering how certain scenes were accomplished. For modern movies, the answer is usually the same: "computers".
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Perfectly choreographed. The positioning of the 2 pursuers and their subtle movements make the cut and splice indistinguishable. The tiny shift in the womans shoulders and dress hem are only noticeable after several views in stop start motion. For a single viewing at normal speed and not knowing what to expect the audience would be pretty impressed with that stunt
A friend of mine is a professional magician but he calls it something quite different (not in thesaurus or in synonyms (google), anyway no matter, & so i had to watch a second time to notice the slight movement of the very,obviously, wide dress & head straightening immediately the dive was complete.Quote:
Originally Posted by 12bolts
Loved Buster when I was a kid.
Often friends remind us of our wedding at home: it seems no one else has had a magician (my friend mentioned above who teaches the new generation in his spare time), a belly dancer (another friend who taught ladies the art, to ad spice to their marriages), & a band to entertain at an ordinary rural wedding. One of my new B.in laws was disgusted to see the belly dancer & left and took about 15 years to revisit.
This is from the 1924 film Sherlock Jr., and although Keaton never publicly revealed how he did this stunt, he claimed it was an old Vaudeville trick his father had invented, and he performed it again for a live audience on the Ed Sullivan Show in 1957. All it requires is the clever use of a trapdoor, and there's significant evidence (both in the footage itself and otherwise) to suggest that they filmed this in real time. Here's the full scene, for actual frame-by-frame control.
https://youtu.be/TA8rrAqip8E?t=40
Pay very careful attention to the shoulders and arms of the person with the suitcase -- once they are in position, it looks very much like they are using their arms to support a decent amount of their own weight, with arms locked and shoulders held low and tight. Once the dive occurs, you can see their shoulders move up and rotate backwards slightly, as they are pivoting their torso down and taking weight off of their arms. Imagine someone supporting themselves on all fours on top of a set of gymnastic parallel bars, with their torso extending out the back of the dress, and through the top of the coffin-shaped section of the back wall, which is in fact a trapdoor. They don't even need to be totally horizontal, they just need to have their torso held high enough and their legs spread far enough that Keaton can dive through an open space and through the trapdoor.
Once he is through, the person steps off the blocks supporting their feet, rotates their torso down and stands in the dress; notice that the feet appear, and weren't there previously. The trapdoor is closed, and the person steps away from the wall, using both hands to close the back of the dress and one hand to keep it closed as they spin around. If this were done with an edit, why would the dress have a massive split going right up the middle of the back?
Furthermore, note the outline of the trapdoor during the main shot, as compared to the following shot. In the first shot, the outline and shadows at the top are much heavier, and the bottom is not flush with the rest of the wall, while in the second shot it is obviously one continuous wall (seen when the wall rotates), and some of the painted details do not match the previous shot (especially the central vertical stripe).
It's still an excellently choreographed and well-performed stunt, but there's no post-production editing trickery here.
I've seen this one done in person. He dives through the opening in her overcoat/dress, between her legs, and rolls through a small door behind her. You can tell he went out behind her because she is holding the rearovercoat/dress seam closed behind her.Quote:
Originally Posted by Jon
Looks like a continuous shot. I think the set up is pre-scene: The woman's head is through the fence, the back of her neck resting on the bottom of the board directly behind her head. Behind the fence she is suspended horizontally. The front side of the dress / slit seat back is draped over the opening. The fence section that will cover the hole is hinged and resting on her back as she is held up. After Mr. Keaton dives through she is let down, the fence section swings with her and covers the opening behind her. Notice the shadow line at the top of the odd shaped section and watch as her legs hit the dress when she's let down, with the one hand she wraps the dress around her and holds it with the other spinning completely around (for no apparent reason) likely to prove she is fully "dressed". I think it's a continuous shot though it might have taken many attempts to get it that smooth.