Are there any objects that constantly emit a specific pitch as an inherent quality? When you picture this object in your mind, it should be emitting a pitch, and this pitch should feel as much a part of the object as its color.
Many people think of something like ‘microwave’, yet a microwave only beeps sporadically, and the pitch can vary from unit to unit.
The best example I have thought of so far is a lightsaber (F#). I know Yoda’s saber is G#, but it’s a nonstandard size. Anything similar you can think of?
I was thinking piano wire, but those can be stretched. Still, the pitch is purely a function of tension and length AFAIK. Same sort of thing is true of basically any acoustic musical instrument.
I don’t hear it unless there’s a ground loop problem which leaks into audio circuits. Other occupations may hear it in more normal situations (working around AC motors?)
Mass, too. the bass strings on a piano or guitar have a tensile core that is spiral-wrapped with another wire; the wrap doesn’t carry tensile load, but adds mass that lowers the frequency for a given tension.
As to the OP’s question, for an object to emit a sound requires energy. I’m not aware of an object that “constantly emits a specific pitch” unless supplied with a power source. Even a tuning fork doesn’t make a sound unless you strike it.
I’ve heard the low hum of high voltage transmission wires when I’ve driven underneath them. And when I’d heard the hum, I asked my physicist boss – What was the cause of the noise? And where does the energy come from? He asked for the frequency, and I could only guess that it was a low frequency, so he said yes, that’s the vibration of the high tension transmission wires, as the 60 cycles AC travels down, and the resulting magnetic field vibrates nearby wires.* So maybe we’re getting closer to what the O.P wants, but you’ve got to admit, this may not fit the “inherent” property clause.
*Physicist dopers, please be gentle with corrections, I’m not trying to spread disinformation, this is just my best recollection of a personal communication. No specific citation is available. Just an example, to tease out the O.P.'s definition of “inherent”.
“Color” is a statement about the reflectivity of a passive object. In absolute darkness, all non-emitting objects are black. They only have color when they are illuminated by an outside light source. And their perceived color then depends on the color of the illumination. E.g. a pure blue object will not appear red under pure red light. It will appear black.
The OP’s use of the term “color” as an inherent quality includes an unstated (and probably unrealized) assumption “… under normal Earth lighting conditions and as viewed by ordinary humans.”
“Pitch” on the other hand is a statement about vibrations being actively emitted by an object. The only way an object can emit vibrations is if it is powered or generates its own power. Which means that if it’s man-made, it has an on and an off mode. And in off mode, it won’t emit a pitch.
Which leaves us with natural objects which generate or convert power. Generators tend to be big, like planet sized.
Converters can be small, e.g. a stone slowly warming and expanding in the sun. But it won’t have a fixed pitch unless A) it’s of a very uniform material & structure, and B) all examples are very nearly the same size.
I think that’s going to limit us to individual molecules or small crystals. Which will have a pitch, but one so low in amplitude & so high in frequency as to be way beyond impercetible to humans.
ETA: the last 3 posts weren’t there when I started.