How a tool actually decides what counts as silence
Silence detection works by measuring amplitude against a threshold — anything below that volume level for longer than a set duration gets classified as silence and removed or shortened. This means "silence" isn't really an absolute concept to the tool; it's whatever falls below whatever threshold you've set, which is exactly why the same recording can produce very different results depending on that one number.
Why the default threshold sometimes gets it wrong
A threshold set too sensitive (catching very quiet sound as silence) can clip off the trailing end of a soft word or a quiet breath that was actually part of speech, not a gap between speech. A threshold set too lenient (only very quiet moments count) leaves noticeable pauses untouched that a listener would clearly perceive as dead air. Background noise level matters here too — a recording made in a slightly noisy room has a higher noise floor, meaning true silence never actually reads as fully silent, and the threshold needs to account for that baseline rather than assuming true digital zero.
Trimming pauses down vs. removing them completely
Completely removing every gap between words or sentences can make speech sound unnaturally rushed and robotic, since natural speech relies on pauses for breathing, emphasis, and comprehension — a better approach for most content is shortening long pauses to a more natural, brief length rather than eliminating gaps entirely. This preserves the natural rhythm of speech while still cutting the genuinely excessive dead air.
Where this saves the most time
Long recordings with significant natural pauses — interviews, lectures, unscripted talks, recordings with think-time between statements — benefit the most from automated silence removal, since manually finding and trimming dozens or hundreds of individual gaps by hand would take far longer than adjusting one threshold and reviewing the result. Tightly scripted, continuously-spoken content has less to gain, since there's simply less silence in it to begin with.