Acoustic Transmission

Visual surveillance through the window pane had reached its limit; auditory intel was required. I noticed a hairline draft whistling through the lower corner of the sash. Beside the wooden moulding lay a hollow metal pen casing, stripped of its ink cartridge. Planting my boots against the sill, I levered the aluminum cylinder into the corner gap until its open tip penetrated the exterior seal. Crouching low, I pressed my ear flush against the polished metal rim. The hollow chamber immediately amplified the courtyard: distant gravel crunching, leaves scraping stone, wind stirring through the iron gate. The perimeter can now be heard.