[Dr Rem]'s linked idea of selectively sounding individual strings of an Aeolian harp by either rotating the entire instrument, or blowing it with a fan, seems to me to be rediculous, since neither moving the fan nor rotating the instrument will satisfactorily select which strings get airflow over them and which are in still air.

So let us mechanise and inventize the process.

The proposed instrument is basically, an aeolian harp, played from a keyboard.

The keyboard works like a pipe organ keyboard, in that each key lifts a pallette which is a kind of Normally Closed air valve. The design of this pneumatic mechanism is well matured in the pipe organ world, so we can progress straight to the next stage by getting a pipe organ and ripping out the pipes. We don't need a big one, we don't need stops and pedals and all that jazz, just a simple portative or chamber organ with one pipe per key will be fine.

The strings work a bit like a piano I suppose. We need to get hold of an old piano and rip off all the keyboard and hammers and everything else leaving us with just the frame, and the soundboard. We need a piano which has the soundboard not totally under the strings, so a normal upright is no good, but a Grand piano should work. Actually a harpsichord might be even better.

Now comes the clever bit. We get some flexible tubing and attach one end of each tube to the wee hole where the organ pipe would have sat on the organ air outlet. We then take the other end of each pipe and mount it on a rack so that it is facing and almost touching the corresponding string of the piano.

Now, when you press a key, a stream of air is directed onto the corresponding string of the piano, exciting it by the von Kármán vortex street effect.

Questions: How to best ensure laminar air flow over the sting? Careful design of tube end or nozzle. Should there be little vertical baffle between each adjacent pair of strings, as a kind of air guide?

More Questions: do the strings need connected to a damper system so that the sound is damped after the key is released?

Deadly final question: the zombie sound of an aeolian harp is at least in part caused by the high harmonics so the wind glisses up and down the harmonic series even on one single string. If we design the positioning of the noxxles with care, can we supress high harmonics and generate a pure tone from a single string using only airflow?
-- pocmloc, Feb 14 2023

Inspiration for this idea Rotating Aeolian Harp
[pocmloc, Feb 14 2023]

Linked from the Aeolian tone page https://intelligent...of-an-aeolian-harp/
[pocmloc, Feb 14 2023]

Two of these glued back to back are what I'm picturing for the rotating harp. https://en.wikipedi...e:Japanese_Koto.jpg
The strings facing the wind get vibrated, the ones behind don't. As it rotates, the strings getting vibrated change. [doctorremulac3, Feb 14 2023]

OK I blew down a PVC tube at a harp string and it barely made a sound no matter how hard I blew. I think quite a high air pressure (or rather velocity) might be needed to excite the string only blowing at a small section of it.
-- pocmloc, Feb 14 2023


[+} for your idea, but //neither moving the fan nor rotating the instrument will satisfactorily select which strings get airflow over them// I guess should have made clear that the strings are around a central tube that blocks the flow. When the strings are upwind in front of the tube, they vibrate, as they turn behind the tube, the wind is blocked.
-- doctorremulac3, Feb 14 2023


[doc] I don't think the tube will block the wind.

[a1] Thanks for the link. I also followed the pingback to "Sound Synthesis of an Aeolian Harp" which is relevant to this idea.

He says: //As air flows past a cylinder vortices are shed at a frequency that is proportional to the cylinder diameter and speed of the air//

He also says: //When the frequency of the vortex shedding is in the region of the natural vibration frequency of the string, or one of it’s harmonics, a phenomenon known as lock-in occurs. While in lock-in the string starts to vibrate at the relevant harmonic frequency//

So I understand this as being that in a constant speed airflow, there is one vortex-shedding frequency, and this excites the string to vibrate at whatever of its natural harmonics is nearest in frequency to the vortex-shedding frequency. And no other harmonics should sound.

The Aeolian harp string is long, and so it has many audible harmonics. As the wind speed rises and falls, the pitch of the string glisses up and down the harmonic scale.

So for my design, all we need is to calculate the desired airflow for each string, so that it produces the required note.

We can also design a different Aeolian Piano which has only one string, and uses the keyboard to control an air-speed regulator, so that pressing a certain key generates airflow at the speed required to generate that particular vortex-shedding tone, which will vibrate the string at that note and that note only.
-- pocmloc, Feb 14 2023


//[doc] I don't think the tube will block the wind.//

Sure it will, 12 to 24 inches in diameter, the strings arranged around it. Picture two kotos glued back to back. (link)

Half the strings in the front facing the wind, half in the back where the wind is blocked.
-- doctorremulac3, Feb 14 2023


Hey! There must be a rule somewhere about arguing about one idea on the annos of another idea!

Oh I see I started it. Um... You are still wrong though so ha.
-- pocmloc, Feb 14 2023


I wonder whether this could be combined with a didgeridoo.
-- pertinax, Feb 15 2023


It could. Whether it should is a more pressing thing to wonder about (hint: it shouldn't)
-- pocmloc, Feb 15 2023



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