What are the three phases of the history of hebrew vowels?
How do we know the Masoretes were not making up the sounds of the vowels?

qamets (long “ah” sound)

patach (standard “ah” sound)

chatef-patach (short “ah” sound)

Tsere (“ey” sound)

Segol (standard “eh” sound)

chatef-segol (short “eh” sound)

chireq (short, “e” as in she)

chireq-yod (long, “e” as in she when followed by a yod)

cholem (“o” sound)
וֹ
cholem-vav (“o” sound)

qibbuts (short, “u” as in rule)

shureq (“u” as in rule)

qamets-chatuf (“o” as in odd)

chatef-qamets (“o” as in odd)
What are the four lengths of vowels?
אָב
father, ancestor
אֵם
mother
אָח
brother
אָחוֹת
sister
בֵּן
son, descendant
בַּת
daughter
אָכַל
he ate