solution: dasperate measures

answer: aeon

based on the words "ascending" and "descending", solvers should hopefully think of ascenders and descenders in typography. each note is a single letter - a note with no stem is one of acemnorsuvwxz, a note with a stem facing up is one of bdfiklt, and a note with a steam facing downards is one of gpqy (the letter j is omitted to avoid any ambiguity). additionally, each measure gives a single word.

by poking at a few of the more suspicious words/phrases, solvers should then be able to piece together crossword clues for each row. Each clue solves for a word with as many letters as there are measures in the row. additionally, once a few words have been found, searching for all of them together should result in the discovery that these are all units of measurement.

as each row has one measure that is just a rest and the number of letters in each answer lines up with the measures, solvers should extract those letters.

clue answer extracted letter
large farm building barn b
buckwheat bulgur or barley grain i
gastropod without shell slug l
a special aptitude or ability talent l
merry pippin frodo or samwise hobbit i
thin woven rope cord o
actress mirren or hunt helen n
first name of cartoon mouse mickey y
charlie who found golden ticket bucket e
mother of mother gram a
french word for a duck canard r
vaccination via needle shot s
deadly enemy foe f
towel holder rod o
a group of sports teams league u
place to lay flowers grave r

reading these letters in order gives the clue billion years (four) which clues the answer aeon.