Absolute ear is a very rare quality in humans. It is the ability to discern a frequency without the need of another reference one. Ciliated cells in the human ear are tuned to individual frequencies, so it is not impossible to achieve this result. I call this quality absolute FREQUENCY ear. I wonder if there is another kind of absolute ear, absolute LEVEL ear. As human ear (and brain) automatically adjusts to background noise, I think that an absolute LEVEL ear is even more rare then an absolute FREQUENCY ear, if not impossible at all.
A sound level meter, of course, gives an immediate audio level measurements. I am looking for an alternate sound level reference, for simple comparison purposes (e.g.: is a computer quiet?), without the need of a sound level meter.
In my computer room I have a fixture with an halogen light dimmer, 220 V 60 Hz, non-reactive. I think it is a commercial SCR. It makes a very small noise (barely audible) when operating. I understand the noise is not made by the SCR, but a by toroidal filter device surrounded by copper wires, that vibrates when current pulses, repeating at the mains frequency of 60 Hz, pass through the wires. The noise sounds like high-pitched, even if its fundamental frequency should be 60 Hz.
I am also aware that there could be some other problems with halogen dimmers. I haven't found problems with interference of the dimmer in the audio system yes, since I often keep the light off, nor have I had problems with the halogen bulb vibrating when dimmed.
I wonder it this small noise, made by the dimmer when operating, can be used as a very coarse noise level reference. Since it is barely audible, I bet it is around 20 dB. I would be happy to hear that noise with the computer on, meaning that the computer is a really quiet one.
Can anyone confirm my guess (20 dB) for the noise produced by an halogen dimmer when operating?
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Topic: Audio level reference (Read 1579 times)