Why do cell phones make that weird echo sound if you’re too close with someone on the same call/FaceTime?
In: Technology
Basically, because the signal is going in a circle with a little bit of delay.
Your phone is smart enough not to detect it’s own speaker on it’s own microphone (since it knows exactly what signal is going out to the speaker it can ignore than coming back in via the microphone). But it’s *not* smart enough to recognize it’s own noises coming from another phone, and there’s a slight delay in transmission from one phone to another.
You talk into your microphone, it goes to the other phone’s speaker and comes out as sound. If you’re close together, your phone’s microphone hears that sound as just another noise it’s supposed to pick up and sends it to the other phone’s speaker (again). And again and again and again, getting a little more distorted and delayed each time around the loop.
Its a feedback loop. Any minuscule sound made on one phone comes out of the speaker of the other, which then gets picked up by the receiver of the first phone, which then gets echoed out of the speaker of the second phone. There’s a bit of amplification involved in the speakerphone mode of any phone, and so the sound gradually gets louder and louder.
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