Difficult to say without the original translation:

http://touregypt.net/godsofegypt/maat2.htm

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Note added at 10 mins (2006-07-06 12:36:02 GMT)
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Justice, Ethique, Le Bien, Beau, Vrai

As Anna Maria says, difficult to tell what is meant here. Maybe it means tone in the sense of "the right tone". Ifound the following in French and chose "exactitude", but you could also go for one of the others: règle, droit, droiture, canon...

A Kémèt (Égypte Antique), la Déesse Maât est la personnification de la Vérité, de la Justice, de l’équilibre cosmique, de la loi, de l’ordre, de la règle, de l’exactitude, du droit, de la droiture, du canon, de la rectitude, de l’intégrité et de la vertu.

Maât, soit la Vérité-Justice, c’est à dire l’ordre cosmique déifié.
http://forum.macbidouille.com/lofiversion/index.php/t128422-...


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Note added at 1 hr (2006-07-06 13:44:19 GMT)
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"Maat was more a fundamental bridging concept rather than a deity to be worshipped. Literally, "mAat" meant also : "truth, integrity, uprightness, justice, the right, verity, social & cosmic order, balance, equilibrium". The fact that "the proper measure" (in Dutch : "de maat", also in words as "maatstaf, maatgevend, matigen") was Ancient Egypt's fundamental concept, shows the importance of balanced, exact & correct thought before the advent of rational categories."

http://www.sofiatopia.org/maat/ptahhotep.htm

From what is said here, I think "tone" might be what they call "the proper measure" (balanced, exact & correct thought) in this text. Not quite sure how you could translate it , though.

I believe "tone" may be referring to music. In Moustafa Gadalla's book "Egyptian Divinities", it says the following about the goddess Ma'at:

Ma'at is related to the harmonic laws of music. (see another book by the same author, "Egyptian Rhythm: The Heavenly Melodies")

Other attributes of Ma'at are listed as:

Harmony, balance, and equilibrium between all the cosmic forces of nature. Also: order, justice, truth, and what is right.

Ma'at is associated with:
administration of justice
passing judgment in the afterlife on those who have died
order and harmony in society
harmonic laws of music

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Note added at 6 hrs (2006-07-06 19:02:35 GMT)
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Hathor was more commonly known as being the goddess of music in general, but I believe Ma'at would be attributed to things like harmonic chords, etc.