Default standard for speaker "sensitivity" measurement listings? Anechoic? In-room? Other?

This is the problem with specs: many many ways to affect results that make them  not comparable to anyone else's measurements.   It's like saying your table is  "brown", it's not an absolute and is not translatable - there are 1,000's of different browns.  

Great point. At least with "brown" we can safely assume it's not being lit by a red or blue or green lamp. It is not-black, not-grey, and not-red -- at least.

Look closely at the graph, box#1 (83.3db) at 500hz, and box#2 (83.7db) at 1kHz.

@russ69 "Except that is where we all end up listening to their products."

Yep, the bottom line is how do they sound in your room, on your system.

HIlde45, yes you get it. the challenge is many want to assign "brown" a specific value. Will we all know for certain what color your table is if you call it a "brown"? Saying a speaker is 92dB efficient means zero. Saying its 91dB SPL 1w/1m at 1K is a proper spec. If someone else says on an spec sheet "91dB SPL" , that is not the same.

Ive seen companies post specs of a speaker as "20 to 20K". No plus or minus variance (so we dont know how much it varies in between 20 and 20K), no distance or power spec. Inverse square law says if you stuck a microphone at 1 meter or at half that distance, those specs would be 3dB apart. So a 92dB (no power or distance) spec could really be 89dB 1 w/1m @ 1K- or worse. For someone searchng for a highly efficient speaker to mate up with his low pwer tube amp, this ommission of info could be costly as it would mean the speaker actually needs twice the power you thought it did.

Another example is your speaker spec sheet says "20-20K". Is this comparable to a spec sheet that says 100-15K +/- 2dB? Which one is better?

Its impossibel to say from this little information but I’m gonna bet the 100-15K +/- 2dB spec is a better speaker because the "20 to 20K" is deliberately deceptive. It could be + or - 20dB, which would be a crap loudspeaker. You have no idea if the spec doesnt tell you how much the Frequency Response varies between the two points. . 20-20K +/- 10dB means the Frequency Response varies as much as 20dB up and down, which is huge! A variation of +/- 2dB is the normal variation we like to see, so the real spec of this 20-20K speaker could be 200-8K +/-2dB @1K ! If it was really 20-20K +/- 2dB, you can bet they would print that +/- 2dB because they would sell more! Everyone in the engineering and manufacturing business knows what a proper spec looks like so this isnt some innocent ommission. This 20-20K is something I often see with "no name" speakers, or bluetooth speakers, or something that is of low quality. So for some companies, sales today is the single most important thing; for others its the integrity of the brand and building up a reputation for quality.

Brad