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From researching on the internet I have learned that microphones output analog voltages and with the help of amplifiers they can store that variating voltages as digital data in case you want to store that audio.

Anyways I want to wake up Alexa by doing gestures as an alternative. On my phone I have a recording that says "Alexa how is the weather today". I want to send that audio to Alexa so that she responds without me having to talk for purposes of learning. Here is my approach:

  1. disassemble Alexa and find the microphones. There should be 4.

  2. Get an audio cable peal one side of it and solder it to one of the microphones of Alexa. I have a 50% chance of getting this right. I don't know what side of the cable goes to the positive and negative.

  3. Connect the other end of the audio cable to my phone and play the audio on my phone.

If I do this experiment will it work?

Edit

I know I can play the audio on my phone to simulate this. I also know I can purchase the Alexa remote control that will wake her up. I am asking this for purposes of learning.

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  • \$\begingroup\$ "From researching .. they can store that variating voltages as digital data.." Uhh. No, no, no. no. Hell no! Microphones can not collect or store anything. \$\endgroup\$ – Oldfart Apr 2 '20 at 11:00
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    \$\begingroup\$ He probably meant MEMS microphones with I2S interfaces (which is what is mostly used on IoT devices such as Alexa and so on). So OP might have interpreted that as "microphone storing digital data". I'm speculating a lot on what the OP wrote though.. \$\endgroup\$ – Wesley Lee Apr 2 '20 at 11:08
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    \$\begingroup\$ Why not play the audio through the phone's speaker and let the Alexa microphone work as it normally does? This would at least prove the concept. \$\endgroup\$ – Dave Tweed Apr 2 '20 at 11:14
  • \$\begingroup\$ Plus, there is probably an API to help send commands to wake up the device (and control it).. no need to hack into it physically. \$\endgroup\$ – Wesley Lee Apr 2 '20 at 11:16
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    \$\begingroup\$ @Tono Nam check the title edit and revert if needed. \$\endgroup\$ – user287001 Apr 2 '20 at 11:19
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I wouldn't have especially high hopes of success. Microphones can be so tightly built into the system that it's even mechanically impossible to make own modifications. The needed wires can be buried under very difficult to disassemble parts on the circuit board and the sheer density of wires can be to high. Think how do you tap to one wire which is one in a bunch which has 4 wires in a millillimeter wide zone. I do not claim you'll meet this but prepare for it.

If the mechanical problems are solvable we do still know nothing about the needed signals. Even in case they are old fashioned electret mics they can get some supply from the rest of the electronics and disturbing it can cause a now unpredictable error condition. At least headphone signal can be as much as 1000x too high, it needs an attenuator.

If you are going to continue get local help. An experienced electronics hobbyist with your Alexa can well be interested in this journey if he is free from all responsibility of caused consequences.

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    \$\begingroup\$ Some Alexa's are able to show the direction of where they think incoming speech is coming from, and it is fairly accurate. So it must be doing some advanced calculations on the four microphones. I'd suggest first identifying the microphone and finding it's datasheet. It may well be near impossible to "inject a signal" if they are something like a MEMS device with \$I^2S\$ output. \$\endgroup\$ – rdtsc Apr 2 '20 at 11:46
  • \$\begingroup\$ I will probably get help to learn faster. Thanks for the feedback! \$\endgroup\$ – Tono Nam Apr 2 '20 at 11:52

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