Poor on-device performance when using the Syntiant DSP block and the Nicla Voice board

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#1

Question/Issue:
When I use the Syntiant DSP block, I only get poor on-device performance for my own models. I have also tried public projects, but unfortunately I am unable to achieve better results. When I train a model with the MFCC DSP block, it works perfectly on my phone. However, the MFCC DSP block cannot be used for Nicla Voice. The Syntiant block behaves similarly to the Audio MFE block, which is good for recognizing non-voice audio. As a last resort, I am now using the Transfer Learning block and achieving good results with it. It feels like I’m doing something wrong.

Project ID:
892621, My current project with just a bunch of audio samples
892624, Basically a clone from 42868 just build for Arduino Nicla Voice

Context/Use case:
As part of my computer science studies, I am investigating the use of local language models as opposed to conventional solutions such as Alexa and Siri. I would therefore like to create a small prototype that recognizes 3-5 words and triggers actions in HomeAssistant via BLE depending on the word recognized.

Steps Taken:

  1. Increased data set size to 10-15 minutes per label
  2. Modified samples (Record samples by phone/board, shift samples)
  3. Modified impulse configuration (number of training cycles, learning rate, auto-weight classes, data augmentation, following the guide ‘Increasing model performance’)
  4. Use a finished project like 42868 or 297564
  5. Switched learning block to Transfer Learning (Keyword Spotting)

Expected Outcome:
Decent on-device performance, at least when using public projects like 42868

Actual Outcome:
Poor on-device performance with both own and public projects when using the Syntiant DSP block. Only the ‘Transfer Learning’ learning block produces decent results.

Reproducibility:

  • [X] Always
  • [ ] Sometimes
  • [ ] Rarely

Environment:

  • Platform: Arduino Nicla Voice
  • Build Environment Details:
  • OS Version: Windows 11 25H2
  • Edge Impulse Version (Firmware): Pre-compiled firmware
  • Edge Impulse CLI Version: 1.37.2
  • Project Version: 1.0.0
  • Custom Blocks / Impulse Configuration:
    No custom blocks, Syntiant DSP, Classification learning block

Logs/Attachments:

Additional Information:
There might be a similar issue mentioned by @madhu_sajc in bug report 14489.
I recorded multiple samples using the built-in microphone. Therefore, it is unlikely that the issue is hardware-related.