The phrase "keenly listened" is correct and usable in written English
It can be used to describe someone who is paying close attention or is very attentive while listening.
Example: "During the lecture, she keenly listened to every word the professor said, eager to absorb the information."
Alternatives: "attentively listened" or "listened intently."
For an hour, Slutkin leaned on the table, playing with a piece of Scotch tape, keenly listening.
ISTANBUL — More than a thousand people sat quietly in a stone amphitheater at a park here on a recent mild summer evening, keenly listening to dozens of Turks who took the floor, one by one, to speak their minds.
With her shock of snow-white hair, she is an imposing presence in the courtroom, keenly listening and motionless except to sip occasionally from a small bottle of mineral water.
But at night, my mind drifts off to the navy horizons of the North Sea, where fishermen are steering their boats with one hand and clutching a mug of rum with the other, keenly listening to these hieroglyphs to keep them out of danger.
When Buffett speaks, investors keenly listen.
Reflecting on senses when in her presence: seeing her, Nancy was elegant-conservative; speaking with her, Nancy was keenly attentive; listening to her, Nancy was gently persuasive.
Ryan listened keenly but, half-deaf with desire, barely heard.
In a tea house in Khost, where scores of arrests have been made over the past months, residents listened keenly to a conversation about the American presence in Afghanistan.
As a pre-teen she queued for hours to get into recordings of Saturday morning show CD:UK, and listened keenly to the Top 40 while doing Sunday shifts at her auntie's Haringey cafe.
They listened keenly, as, amid the dizzying facts and figures about Uber's hyper growth, Kalanick also peppered his speech with a two-pronged message, with one proviso — that Uber can help solve Europe's unemployment problem and help it meet it's environmental targets.
