Effect of Humming on Vision

August 4, 2022 10:46 AM

The bait (or assignment).

The article (or answer sheet).

posted by aniola (14 comments total)

The link should be: The article.

I wonder if the strobo-scopic effect can be used to determine the speed of a rotating object by humming at various frequencies and seeing if there's an effect on your vision when the humming frequency is in sync with the rotating frequency.
posted by eye of newt at 11:06 AM on August 4, 2022 [2 favorites]

from where i sit, eye of newt's link is a $32 paywall but aniola's OP is an article. i route around damage.
posted by glonous keming at 11:10 AM on August 4, 2022 [5 favorites]

The link in the FPP is to an article by W.A.H. Rushton. The article (more of a comment letter, really) cited in the assignment is by P.C. Eastman, responding to Rushton's article. But the Rushton article is the more detailed one, anyway. Here is Eastman's letter, in full:

I WISH to comment on Rushton's article on humming and vision1. If a cathode ray oscilloscope (CRO) is operated in a free running sweep mode with a horizontal speed of about 100 cm/s, an observer will see a single horizontal straight line, as expected. If the observer coughs or clears his throat he sees a transient signal. If he sustains a “throat clearing” vibration of about 50–100 Hz, he will observe a steady sinusoidal signal on the CRO. The amplitude of the signal depends on the observer and his vocal intensity, a typical value being 5 mm at a distance of 200 cm. The amplitude increases with distance. Humming does not produce a detectable signal.
I explained this effect by assuming that the eyeballs were vibrating at the driving frequency. A further observation was that the eyeballs vibrated in the sagittal plane, normally up and down, and this can be seen when the observer tilts his head in a lateral direction. The sinusoidal signal induced by throat clearing takes on the characteristics of a saw-tooth as the tilt is increased and finally becomes an intensity modulated line after a rotation of 90°. This direction may be fixed by the way in which the throat vibrations couple through the head to the eyes, or by some muscular constraint on the eye itself. The latter explanation seems more likely, for when a mechanical vibrator was used to shake the head in various modes, the resulting signals on the CRO were always seen as displacements in the up and down direction (with regard to the head), and lateral displacement could not be induced.
Since reading Rushton's article I have tried the throat clearing effect on a strobe disk and have noted that here also the polarization effect is clearly visible.

(copy-pasted from an OCR'd PDF, so apologies for typos)
posted by jedicus at 11:16 AM on August 4, 2022

Hey, I figured this out myself as a teenager! Had a computer with a CRT monitor. Made high-pitched sound (exploratory research). Saw the refresh (whoa!). Tried different frequencies (I CAN CONTROL REALITY). Tried high-pitched sounds on framed picture (no visible refresh), TV (visible refresh), cat (confounded effects). Extensively checked reproducibility, pleasing my parents with my grasp of the scientific method (at least it wasn't magnets this time).
posted by aws17576 at 12:47 PM on August 4, 2022 [8 favorites]

Any other ways of seeing this if you don't have a turntable or CRT handy?
posted by straight at 1:01 PM on August 4, 2022

I've heard that playing one of the lowest notes on a contrabass clarinet can make your eye jelly jiggle so much that you can't read sheet music.
posted by Greg_Ace at 1:25 PM on August 4, 2022 [5 favorites]

I read that as P.D. Eastman and was briefly agog and amazed. Wave, tube, wave!
posted by johnofjack at 1:44 PM on August 4, 2022 [6 favorites]

also if you blow a raspberry in front of a digital display it wiggles
posted by The otter lady at 2:13 PM on August 4, 2022 [2 favorites]

Greg_Ace,

I played contrabass clarinet in junior high school. I never noticed my jelly jiggling. But it did get my photo in a local paper, a kid blowing into a big metal loop of plumbing.
posted by njohnson23 at 5:14 PM on August 4, 2022 [3 favorites]

Similar effect happens when chewing ice; noticed when watching a b/w CCTV monitor.
posted by achrise at 6:40 PM on August 4, 2022

I played contrabass clarinet in junior high school. I never noticed my jelly jiggling.

Well, shoot. The internet lied to me!
posted by Greg_Ace at 7:53 PM on August 4, 2022

Bass clarinet reporting in (can't believe I'm not the first big clarinet comment, damn). I got dramatic jiggle on my lowest Eb, so clearly there's considerable variability in operator eyeballs.
posted by McBearclaw at 8:31 PM on August 4, 2022 [5 favorites]

Now read music while flutter-tonguing!
posted by Coaticass at 8:36 PM on August 4, 2022

All those experimenting with this should take care not to hit the brown note.
posted by jamespake at 1:23 AM on August 5, 2022