Like a good percentage of human males, I'm partially color blind to green and red. In my case, it's enough that I can't tell the difference between a green or a red LED -- so a piece of equipment that depends on the operator being able to see the color of a bi-color LED is totally useless to me.
Needless to say, this is irritating.
Does anyone on the group know how many people are really, truly tone deaf? I don't just mean unable to hear when they're playing out of tune, but people who are unable to tell the difference between a "beep" and a "boop" when it's coming out of a piece of electronic equipment?
I'm thinking of communicating status via a beeper, and for obvious reasons I don't want to do the same "bicolor LED" crap to someone, only with sound.
I can't imagine how that could be the case for anyone that wasn't completely deaf. Not being able to tell an A from a C is one thing, but it seems like if you couldn't resolve octave differences you wouldn't be able to understand English, let alone a tonal language like Mandarin.
Ears are just simpler hardware.
Rob Gaddi, Highland Technology -- www.highlandtechnology.com
Email address domain is currently out of order. See above to fix.
Avoiding answering the question directly (that's the Usenet way, isn't it?):
Tone discrimination seems to be culturally mediated - some asian languages are tonally dependent, and amazingly enough people from those lands have a much higher incidence of "perfect pitch". In western cultures perfect pitch is a small minority.
That aside, I'd think about using tonal patterns - either changing frequency, or making a quasi-Morse-code out of it. There are some people that simply can't "get" melody, but I'm fairly sure these are comparatively rare. Maybe go all the way and synthesize voice messages!
Oh yes - one day your color blindness may be history. It's only been tested in monkeys so far - but these animals (color blind from birth) have been genetically treated to express color sensitive chemicals in their retinal cone cells that they had lacked. It has yet to be tested in humans (so far). Not soon enough for your application, I'm sure :)
Reg/Green colour blindness is very common. I thought most people could discern blue and red.
I'm sure the same is true with frequency.
One issue with frequency is for most people pitch is relative, such that I can tell the difference between two notes one after the other, but I would be unlikely to discern which is which if you produced just the one. Perfect pitch hearing is very rare.
However I would have thought a form of modulation could overcome any colour blindness or extreme tone deafness.
I hate those piezo beepers. They are annoying, and hard to localize.
If you use a small speaker, you can synthesize bell sounds, chirps, patterns, structured stuff that sounds nicer and is easier for everyone to distinguish. Make a cheerful sound for good things, a raunchy one for errors, modulate amplitude if it might mean something.
I'm not tone deaf (my hearing is great, mechanically) but I don't like music and I have a very hard time understanding accents. It's a signal-processing thing.
John Larkin Highland Technology, Inc
jlarkin at highlandtechnology dot com
IIRC, it's something like 1 in 15 (among men). What's amazing is how ignorant many people are of this fact -- esp folks who ADVOCATE the use of color in indicators!
(Low light conditions also wash out color sensitivity in most people)
Depends on what you mean by "Tone deaf". Many people can't carry a tune in a bucket -- yet can synthesize and recognize *difference* in tone. Most musicians *don't* have "perfect" pitch but, instead, rely on "relative pitch" (recalling the ratios of frequencies though requiring "calibration" to some recently heard "reference tone")
Modulate (gate) the sound to that it manifests as short and long "sounds" and "silences". Taking care to include a long and a short in each "report" to serve as a reference for the user. Of course, you also have to avoid the extremes in frequency range as they tend to alter with age (stick to the sweet spot -- speech -- in the audio band).
The same applies to blinking indicators -- regardless of whether they are multicolor or monochromatic.
Trying to address accessibility issues involves quite a bit more.
E.g., dealing with a *deaf* user will leave you stumped! Hearing users can have their attention drawn to with a percussive noise. When the party you're interested in can't perceive this, you have to come up with other ways to get them to *notice* the flashing light, etc.
Think about how your product is normally used, interacted with, etc. and see how you can inject an "asynchronous notification" therein.
Personally I think it's best to use code. Beeeeeep - good. Bip .. bip .. bip .. bip - sumpthin's wrong. No sound - it ain't working. I wish that was the same for optical displays.
A client goes a step further. They are using morse code to announce the status of a system. I could turn it on, go down the hallway and into the kitchen to get a glass of water and still hear whether it started up alright and what firmware version is in it.
If it's just for bench equipment, could you keep a red or green filter (colored cellophane or whatever) handy? Then just hold the filter in front of the LED to check the LED color. Red cellophane will make a green LED look dim while not significantly decreasing the apparent brightness of a red LED, and vice versa.
As an obvious an easy to implement solution, why not go to yellow/blue LEDs? Almost anyone except the very rare individuals with total color blindness, will be able to distinguish those, including almost all cases of partial color blindness. Yes, those are relatively expensive (about twice the cost of red/green bi-color LEDs), but would likely be a near plug-in solution.
In the case of audio, mix different frequencies with different pulse rates. IOW, BeepBeepBeep vs. Boop...Boop...Boop vs. Tic..Tic..Tic.
While there are people who cannot hear certain frequency bands, that's usually the result of some sort of trauma or exposure to very loud noises. A complete inability to distinguish tones would make them unable to understand speech as well.
Of course, some colored film or 'gels' would be much cheaper and just as handy.
Guessing you want glasses that null the offending colors -- purple absorbs green, making green look black (in the most common red-green colorblindness). Presumably, cyan would also work (complement of red, making red look black instead -- so don't mix up your cyan and purple 'shades!). It follows, you want the complementary color for whichever type of colorblindness you have; the other kinds, being rarer, presumably have rather expensive glasses for them, making the cheap solution all the more handy.
Deep Friar: a very philosophical monk.
I can do you one better. One time while driving with my girlfriend (at the time), she attempted to provide directions: [points to the right] "go yellow!" "I mean, left!" "I mean, RIGHT!"
I didn't let her live that one down...
Speaking of cars, most have a diagnostic mode (enabled by jumpering the diagnostic plug, or doing a magical dance, e.g., toggling ignition five times) which blinks out diagnostic information. Newer cars (i.e., since the 90s) of course have various numeric, alphanumeric or graphical displays in them, but older ones often used the "check engine" light. My '95 Toyota, for example, blinks out unary sequences:
- a blink is something like 0.2 seconds ON, 0.8 seconds OFF
- a series of blinks in a row is a digit (i.e., count the pulses, 1 through 9 -- not BCD, but UCD -- unary coded decimal)
- An extra second between blinks indicates the second digit (thus expressing numbers 11-99 except whole multiples of 10, since there's no zero)
- Two seconds delay indicates another pair of digits (if multiple error codes are present)
- Five seconds delay and the sequence repeats
I probably have the exact times wrong, but the grouped pattern is clear and pretty handy. Unary gets tiresome after a while, so if you need status faster than it blinks, you'll need a different method.
Deep Friar: a very philosophical monk.
I.e., if they occur adjacent to each other in *time*, you still have to be able to resolve the difference in pitch/frequency to differentiate them.
E.g., if the two notes differ by a semitone, you or I can indicate hi-lo vs. lo-hi. But, this may not be possible for all "listeners".
And, if the "tune" c ding...dong.dong error 93 ding.ding.ding error 27 ding...dong...dong error 15
(Try it and notice how *you* remember the annunciator while attempting to look it up! Then, have one of your friends listen to it and try to convey that information to you "over the phone". Or, in an email...)
You want to choose "indications" that are sufficiently different to maximize the chance of differentiating between them. E.g., perhaps 6-12 semitones apart; durations that vary by a factor of
2 or 3, etc. And, keep the number of "events" (indications?) small so the user can hold the entire sequence in his/her short term memory while trying to write it down, look it up, explain it to someone else, etc.
The same holds for audible, visual, haptic, etc. interfaces. (you often have to resort to combinations of each of these if you want to design inclusively)
Or, just hope everyone that interacts with your product has 100% sensory capabilities! :> (and be chagrined when you discover just how many people are "impaired" in various ways -- and, how
*an* impairment can often be just "one of several")
~0.5% legally blind in the US (1.5M) ~8% of men are colorblind (doesn't affect women as much!) ~5% of 50+ have essential tremor ~1% of 60+ suffer from Parkinsonian tremor ~1.5% "deaf" (e.g., 4M in the US) etc.
And that doesn't address other "physical" impairments, etc.