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Speech-Enhancing Bluetooth Microphone Demo

This example shows how to use Ambiq's NNSE to create a 'Speech Enhancing USB Microphone'. NNSE is Ambiq's AI speech de-noiser, a real-time AI model that removes background noise (such as the noise from a hair-dryer) from human speech.

sequenceDiagram
    participant Microphone-on-EVB
    participant NNSE
    participant Opus-Codec
    participant WebUSB
    participant Chrome-on-PC
    Microphone-on-EVB->>+NNSE: 10ms Raw Audio
    NNSE->>+Opus-Codec: 10ms Clean Audio
    Microphone-on-EVB->>+NNSE: 10ms Raw Audio
    NNSE->>+Opus-Codec: 10ms Clean Audio
    Opus-Codec->>+BLE: 80 byte 20ms Opus Audio
    WebUSB->>+Chrome-on-PC: 80 byte Opus Audio

Hardware Requirements

  1. Apollo4 Plus or Apollo510 EVB
  2. VOSKit PDM or analog microphone (AP4 only)
  3. PC or laptop running Chrome

This demo supports both PDM and AUDADC microphones, but is configured for PDM by default. To switch to AUDADC, uncomment this line in nnse_usb/src/nnse_usb.cc:

// #define USE_AUDADC // Uncomment this to use the AUDADC instead of the PDM

Running the demo

First, flash 

$> make clean
$> make -j
$> make EXAMPLE=demos/nnse_usb deploy

With the firmware deploy, follow this link on a PC using the Chrome browser: Audio WebBLE Demo

The webpage should look something like this:

image-20231106120630313

Click on the 'Pair and start listening...' button to bring up a list of compatible WebUSB devices. Once paired, the web dashboard will play the audio (click the play button to allow the browser to actually play the stream) and show corresponding waveforms and spectrograms.

Once everything is working and audio is streaming, you can turn de-noising on and off by pressing Button0 on the EVB.

Recommendations

The EVB's microphone will pick up the audio being played by the PC, often leading to a feedback loop. We recommend using headphones connected to the laptop to prevent this feedback.

For a more effective demonstration, use noise-cancelling headphones and introduce noise to the environment such as a hair dryer, traffic noise, or similar. The noise cancelling headphones should remove most of this ambient noise. When the EVB is in raw audio mode (as mentioned above, you can switch between modes using Button0 on the EVB), the EVB microphone's audio will be passed to the headphones, and the user will hear the ambient noise. When the EVB is in speech de-noising mode, the ambient noise will be removed but any speech will be cleaned up and passed through to the user's headphones.