Turn on Brief Mode in the Alexa app. On supported requests Alexa can acknowledge an action with a short sound instead of saying “OK.” This is particularly useful with lights: when you can already see the lamp switch off, a spoken confirmation adds little.
Find the voice response setting
Open More in the Alexa app, select Settings, then Voice Responses. Switch Brief Mode on. Use a simple command you know works, such as turning on a named lamp. Listen for the acknowledgement and check that the lamp actually changed. The setting adjusts how Alexa answers; it does not repair a disconnected bulb.
Know when speech makes sense
Ask for the time and a spoken answer is still useful. Ask for a light that shares its name with another device and Alexa may need clarification. Amazon describes the shorter sound as a possible replacement. Do not interpret one spoken reply as proof the setting failed.
Isolate the voice you are hearing
Try the same lamp directly and then through a routine. If speech happens only in the routine, inspect its actions for a custom announcement. A delivery alert, a suggestion and a requested answer also come from different features. Changing one setting at a time preserves the alerts you actually want.
For the documented details, see Brief Mode settings.
Common questions
Will Alexa become silent?
No. Questions and errors may still need speech.
Does it mute music?
Media volume is separate.
Can I switch back?
Turn Brief Mode off in Voice Responses.
What if one skill keeps talking?
Test a built-in request separately to isolate the skill.