Fletcher Munson Vs Robertson Dadson

[inertial]

HI guys,

Please look at theese 2 graphs:

Per PHON1933:



Per PHON1956:



first is 1933, Fletcher - Munson

second is 1956, Robertson - Dadson ( today ISO 226)

please refresh my memory: does the two graphs was performed under equal listening conditions ?

One speaker in front of listener for both ? ( anechoic room?)

OR

Headphones for both ?

My bad memory, I'm start to become old!

Very thanks !
Cheers,
Paolo

[planet10]

I can't answer your question, but i did do an overlay to make them easier to compare

dave

[Pano]

Thanks for the overlay, Dave. They are a bit different, aren't they?

The 1956 chart is what I see published most often.

IIRC, all done with headphones. And all done with pure tones. The ear is more sensative to broad spectrum noise than it is to pure tones, at least in the high freqs.

[forr]

I suggest you have a look at more recent works :
http://en.wikipedia.org/wiki/Equal-loudness_contour
http://www.zainea.com/equalloudnesslevel.pdf

[inertial]

HI guys and thanks for interst,

panomaniac, are you sure of headphone for both ?

Becaus Thanks to Forr, I have founded this in wikipedia :

The Robinson-Dadson determination used loudspeakers, and for a long time the difference from the Fletcher-Munson curves was explained partly on the basis that the latter used headphones. However, the ISO report actually lists the latter as using "compensated" headphones, though how this was achieved is not made clear.


This is official I suppose.
FM 1933 headphone
RD 1956 speaker

This is exactly what I was searching for. But the last phrase are ...doubtable (?).... "compensated" or not?

Cheers,
Paolo