This is the 9618th most frequent Japanese word.
聞き取れ
"聞き取れ" means "can understand (by listening)."
In this sentence, 聞き取れませんでした indicates an inability to understand auditory information due to the speed of the speech.
彼の言っていることが早すぎて聞き取れませんでした。
His speech was too fast for me to understand.
Here, 聞き取って means to catch or understand auditory information from the provided source, emphasizing attentiveness.
その音声を注意深く聞き取ってください。
Please listen carefully to the audio.
In this usage, 聞き取る implies the skill or ability to comprehend spoken language.