I guess that all depends on your definition of the word "functioning." Technically, if you've got a task to do, some people could use their hands to feel around after using their light for a brief, orienting flash and environment check. Most of us, however, would call that extremely difficult and annoying, I sure would. Given that, I personally cannot stand inductor whine and am extremely sensitive to it. The sound itself is similar in frequency to the teen cellphone ringers that most people over 40 have trouble hearing. I own a wireless radar detector that has helped me, several times, prove that I have either vastly superior hearing or an incredible sense of rhythm. Since I'm a musician, neither is out of the realm of possibility:
After turning on the detector, it pulses a red LED. The thing is, I hear an additional pulse in between pulses of the red LED. I haven't used it for awhile (it gave me headaches), but let's say the red LED pulsed at 40 beats per minute (BPM). I would hear a pulse that went 80 BPM. This gave me the opportunity to prove to people that I could hear it. I'd ask them to turn on the device, turn it away from me, even go to another room so that I could not see the LED (which gave the observer the tempo since they couldn't hear the sound I could). Then I'd walk in and conduct to the tempo that the pulse gave me. Now that I think about it, the pulse was more like 100-120 BPM. Either way, I even proved to other musicians that some people, even amongst musicians, have sharper hearing than others.
The biggest reason I've made this my crusade is because when I was a kid, I would constantly walk into offices that just had computer systems installed. I remember when the Mouse was introduced as an input device and computers didn't have hard drives! Anyway, my dad, and whatever other adults were around, thought I was just a whiny kid when I complained that the noise was hurting my ears. I hated the look they would get whenever I'd ask them "you don't hear it?" Now I know better.
Thanks for starting this post. I hope you don't think, OP, that I'm trying to hijack it, I just want readers to understand what may not be annoying for you may be extremely painful for others. I returned a Nitecore D10 which had unacceptable inductor whine. Though the two I got in exchange had violet and green tints, I figured that was better than the whine. I now know that I'm not going to take a chance on this light for this reason. Call me crazy if this isn't an issue to you, but whine kills me on lights.
Both are dead quitet. I can hear my fenix tk20 and nitecore d10 across the room.
