The first prophetic message delivered to the young Samuel brings no comfort, but instead unveils a devastating decree destined to strike both the nation's leadership and the people. God speaks to Samuel at this specific moment to validate and enforce an earlier prophecy of doom that had been delivered to Eli the Priest. Because prophetic visions were incredibly rare during that era, Eli most likely doubted the truth of that initial warning and remained silent. By delivering this severe message through a young boy, God ensures that Eli will understand beyond any doubt that this is His absolute, unquestionable word [אברבנאל].
The impending event is universally understood as a massive national and personal tragedy. It sets off a chain reaction of catastrophic losses: the Ark of the Covenant will be captured by the Philistines and taken into exile, the Tabernacle in Shiloh will be destroyed, the Israelites will suffer a crushing defeat in battle, and Eli along with his two sons will die [רש״י, רד״ק, מלבי״ם, אלשיך].
The sheer shock of this future disaster is so intense that it will physically affect those who learn of it. The primary approach among commentators is that the news will strike with the force of a sudden, loud noise, echoing and piercing the ears much like the crashing of cymbals. Beyond just a harsh sound, the reaction involves physical trembling. The profound dread and horror of the calamity will be so overwhelming that it will cause the listeners' ears to physically quiver in deep terror [רלב״ג, מצודת דוד, מצודת ציון, מלבי״ם, שטיינזלץ].