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Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Oído is an open-source speech-recognition project designed to transcribe English locally on an ESP32-S3 microcontroller, without cloud processing or a fixed command list. Lokutor reports promising LibriSpeech accuracy, but its September 30, 2026 status note still estimated speed from emulator data rather than measurements on physical silicon. Building the documented setup also requires a specific ESP32-S3 memory configuration and an I2S microphone.
What Oído does—and what “open vocabulary” means
Oído is a speech-to-text engine written in C for the ESP32-S3. Unlike a command recognizer limited to a predefined list, it is intended to transcribe open-vocabulary English speech. Its design targets a dual-core 240 MHz Xtensa LX7 with 8 MB PSRAM and 16 MB flash; these are project specifications, not independent hardware test results. The engine is described as operating without cloud processing or a neural accelerator. Lokutor’s repository and its October 1, 2026 launch post describe the project.
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The documented architecture combines a log-mel audio front end, convolutional subsampling, a 16-layer Conformer encoder, and CTC decoding over 1,024 BPE tokens. The implementation also supports an RNN-T head and an optional GRU language model used with CTC prefix beam search. Its C code includes quantized kernels, dual-core scheduling, and utterance segmentation. This is a fairly substantial recognition pipeline for a microcontroller, rather than a small collection of hand-matched voice commands.
How accurate are the reported results?
Lokutor reports word error rate (WER) on LibriSpeech’s test-clean and test-other sets. Lower WER means fewer word substitutions, deletions, and insertions under the project’s text normalization. The figures below are maintainer-reported results, not an independent benchmark. For Oído’s on-chip configurations, the repository says it used the full test sets.
#1 Best Overall
- 🔥【Dual Mode & High Performance】 The ESP32-S3 development board features integrated dual-core xtensa 32-bit LX7 microprocessor, clock speed up to 240 MHz, with 16MB Flash and 8 MB PSRAM. Perfect for Arduino IoT projects requiring stable wireless communication with ultra-low power consumption.
- 🔧【Easy Programming & Debugging】 Equipped with dual USB Type-C ports, this ESP32-S3 board supports both USB and UART modes for effortless programming, firmware flashing, and debugging.
- 🌐【Versatile Wireless Connectivity】 Built-in Wi-Fi (2.4GHz) and Bluetooth 5.0 (LE) dual-mode ensure seamless connectivity with a wide range of smart devices, making it ideal for IoT, smart homes projects.
- 🚀【Flexible Download Options】 Supports dual download methods — USB direct download or USB-to-serial download — offering flexibility and convenience for different development needs.Ideal for beginners and developers working with ESP32-S3.
- 🔋【Advanced Power-Saving Modes】 Designed for energy-efficient applications, with 3.3V SPI voltage, the ESP32-S3 board supports multiple low-power modes, allowing you to extend battery life based on different usage scenarios.
| System and configuration | Test-clean WER | Test-other WER | Comparison notes |
|---|---|---|---|
| Oído, int8, greedy | 3.7% | 8.2% | Lokutor-reported; full test sets |
| Oído, int4, greedy | 4.6% | 10.0% | Lokutor-reported; full test sets |
| Oído, int8, with on-chip language model | 3.3% | 7.2% | Lokutor-reported; full test sets |
| Oído, int4, with on-chip language model | 3.8% | 8.4% | Lokutor-reported; full test sets |
| Espressif MultiNet7 | 8.5% | 21.3% | Repository comparison; fixed command-list API |
| Moonshine tiny, laptop baseline | 5.0% | 12.1% | Repository says laptop baselines use 500 evenly spaced utterances per set |
| Whisper tiny.en, laptop baseline | 6.3% | 15.9% | Repository says laptop baselines use 500 evenly spaced utterances per set |
| Vosk small, laptop baseline | 9.9% | 21.6% | Repository says laptop baselines use 500 evenly spaced utterances per set |
These results suggest that the project’s reported Oído configurations perform well on those benchmark sets, including relative to the listed fixed-command system. They do not establish how it will perform with every accent, microphone, speaking style, or acoustic environment. The laptop rows also use a smaller sample than Oído’s on-chip rows, so they are not an exact like-for-like test-set comparison.
Does it actually run in real time on the physical chip?
That was not yet established in the repository’s September 30, 2026 status note. Lokutor said host execution was bit-identical to the firmware’s arithmetic and that emulator transcripts matched word for word. The project estimated a real-time factor of 0.7–0.95 from QEMU instruction counts and assumed cycle and stall behavior; it explicitly was not a measured silicon result. A factor below 1 would indicate processing faster than the audio duration, but this estimate should not be treated as proof of physical-board speed.
Rank #2
- ESP32-S3-DevKitC-1-N16R8 SPI voltage: 3.3v, ESP32-S3-DevKitC-1 is an entry-level development board equipped with Wi-Fi + Bluetooth module ESP32-S3
- Most of the I/O pins on the module are broken out to the pin headers on both sides of this board for easy interfacing. Developers can either connect peripherals with jumper wires or mount ESP32-S3-DevKitC on a breadboard.
- The ESP32-S3-DevKitC development board equipped with ESP32-S3-DevKitC-1-N16R8, a general-purpose Wi-Fi + Bluetooth LE MCU module that integrates complete Wi-Fi and Bluetooth LE functions.
- ESP32-S3-N16R8 cable can be used: USB Type A to Type-C cable or CC cable Note the distinction between the commonly used USB A port to Type-C cable that can only be charged, which cannot be used for communication between YD-ESP32-S3 and the host.
- USB-to-UART Port and ESP32-S3 USB Port (either one or both), default power supply (recommended)
The repository also reports approximately 2.4 MB peak working memory for a 20-second utterance, measured in QEMU. That is a project-reported emulator measurement, not a physical-board memory test. Its status note said physical-board speed measurements were expected in the following days, but the cited evidence does not establish their outcome.
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The repository’s physical build specifies an ESP32-S3-DevKitC-1 N16R8 (16 MB flash and 8 MB PSRAM) and an INMP441 I2S microphone. Do not assume every ESP32-S3 development board has the memory configuration the project targets. The microphone wiring listed by the project is:
Rank #3
- 【Low-power performance】: The AYWHP ESP32-S3 Core development board integrates a 2.4 GHz Wi-Fi and Bluetooth 5 (LE) dual-mode communication module, perfect for Arduino Internet of Things (IoT) projects.
- 【Simple programming and debugging】: The ESP32-S3 module makes it easy to program and burn in your ESP32-S3 board via dual USB Type-C ports, with a choice of USB or UART modes.
- 【Multiple Power Saving Modes】: The ESP S3 development board supports multiple low-power modes, which can be configured according to different application scenarios to provide longer battery life.
- 【Dual download modes】: The ESP S3-1 module supports both USB direct connection download and USB to serial port download, providing more flexibility and convenience.
- 【Diverse connectivity options】: The ESP32-S3-1 supports dual-mode Wi-Fi and Bluetooth 5.0 (LE) connectivity for a wide range of smart devices, making it ideal for Internet of Things (IoT) applications.
| INMP441 connection | ESP32-S3 pin |
|---|---|
| SCK | GPIO4 |
| WS | GPIO5 |
| SD | GPIO6 |
| L/R | Ground |
A 0.96-inch SSD1306 OLED is optional for displaying transcript text. The documented connections are SDA to GPIO8 and SCL to GPIO9. Check the exact board memory variant and component compatibility against the current repository instructions before assembling a build.
If you want to explore without buying the board, Lokutor says its laptop host build can run the chip’s arithmetic and support a live-microphone demo. That can help you try the engine, but it does not validate speed on an ESP32-S3.
Rank #4
- 【ESP32-S3 PERFORMANCE】Dual-core 240MHz processor with 16MB Flash and 8MB PSRAM for IoT, AI, and machine learning projects.
- 【WIRELESS CONNECTIVITY】Onboard antenna for 2.4GHz WiFi and Bluetooth 5.0 LE — for smart home devices, no external antenna needed.
- 【LEAD-FREE GOLD EDITION DESIGN】Immersion gold (ENIG) plating for durability and conductivity. Lead-free, RoHS-compliant — for long-term prototyping.
- 【PRE-SOLDERED, PLUG-IN DESIGN】ESP32-S3 boards come with pre-soldered headers and plug directly into the included expansion and terminal boards — no soldering required.
- 【MULTI-PLATFORM COMPATIBILITY】Works with C++, MicroPython, ESP-IDF, Raspberry Pi, and STM32 — with online tutorials for quick start. Power via USB-C (5V) or VIN pin (5–12V); do not exceed 5V on the USB-C ports.
What are the practical limitations?
- English only: The README describes English recognition, not multilingual transcription.
- Utterance-level output: It returns results by utterance rather than streaming words continuously as someone speaks.
- Challenging acoustics: The project identifies very noisy crowds and reverberant rooms as difficult conditions.
- Hardware speed remains the key uncertainty in the cited status: Emulator agreement and an estimated real-time factor do not replace a physical-board timing measurement.
Benchmark WER should therefore be read as a result on a named test set, not a general promise about live use. For an application that depends on immediate word-by-word captions, languages beyond English, or reliable recognition in difficult rooms, the documented capabilities do not establish that Oído is a fit.
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1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problemsWhat do the model sizes and licenses mean for a build?
Lokutor lists the int8 model at 14.0 MB and the int4 model at 8.3 MB. Its repository identifies the engine code as GPLv3, the int8 model as CC-BY-4.0, the int4 model as CC-BY-SA-4.0, and the language model as CC-BY-4.0. The project’s reported sizes and license labels are not a substitute for reviewing the current notices and exact terms for the files you plan to distribute.
Best Value
- 【GOLD EDITION — IMMERSION GOLD PCB】The Lonely Binary Gold Edition features a black PCB with lead-free immersion gold (ENIG) plating and clear silkscreen — the signature finish of the Lonely Binary Gold Edition line. RoHS-compliant.
- 【16MB FLASH + 8MB PSRAM】Large memory capacity for OTA updates, large programs, and AI/ML tasks — more headroom than 4MB boards for data-intensive IoT and automation projects.
- 【EXTERNAL IPEX ANTENNA】External IPEX antenna can be positioned for extended WiFi and Bluetooth signal coverage — for remote applications like weather stations, robots, or enclosed builds.
- 【DUAL USB TYPE-C PORTS】Separate power and data ports for macOS, Windows, and Linux. Power via USB-C (5V) or VIN pin (5–12V); do not exceed 5V on the USB-C ports.
- 【FLEXIBLE PROTOTYPING PINS】2x40-pin GPIO headers compatible with breadboards and sensors. Supports external ToF sensors via I2C for distance sensing.
Lokutor says commercial licensing and integration support are available for products that cannot meet GPLv3 terms. That is the project owner’s statement, not legal advice. Device makers should assess the code and each model’s license separately before shipping.
Who should consider Oído?
Oído is most relevant to developers exploring local, open-vocabulary English transcription on constrained hardware, especially when avoiding cloud processing is important. Its reported benchmark scores are notable for the target device class, but the evidence cited here leaves physical-board speed unverified. A prototype should use the specified N16R8 memory configuration, a compatible I2S microphone, and real-world audio tests that reflect the intended environment.
For further detail, consult the project repository and README and the launch post. A project discussion also surfaces a practical question—whether microphone audio-cleanup hardware is needed—but that discussion does not establish that such hardware is required: r/esp32 discussion.
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