Enhancing Embedded Safety and Accessibility with Audio ICs from Epson and Nuvoton

Introduction – Why Audio ICs are Becoming Essential in Embedded Safety and UI Design

For decades, engineers have relied on visual indicators, displays, and buzzers for feedback in embedded systems. But, as user expectations evolve and, as safety, accessibility, and interactivity take centre stage, audio is rapidly becoming an essential design layer in both industrial and consumer devices.

Audio ICs are now doing far more than playing tones or alerts. In health and safety-critical environments, they offer proactive guidance through voice prompts, real-time warnings, and context-aware notifications. In user interface design, they enhance usability through intuitive voice feedback, especially where screens are impractical or users are visually impaired.

This shift is being supported by two complementary technology classes:

• Voice/Audio MCUs and Speech LSIs from Epson - ideal for deterministic voice playback, multi-language prompts, and ultra-low power applications.

• Advanced audio processors, amplifiers, codecs, and voice assistance ICs from Nuvoton - designed for higher-performance recording, playback, echo cancellation, and smart audio pipelines.

Together, these platforms enable engineers to embed speech feedback and audio interactivity in white goods, healthcare monitors, wearables, HMI panels, and safety-critical systems like gas alarms, infusion pumps, EV chargers, and autonomous equipment.

Epson Audio ICs for Safe, Accessible Voice Prompts

Epson’s dedicated voice/audio IC family has found wide success in applications where simplicity, clarity, and cost-efficiency are paramount. At the core of the offering are two approaches: Voice MCUs (e.g. S1C31D50/51/41) for full integration, and Speech LSIs (e.g. S1V3G340, S1V3F35x series) for drop-in augmentation of existing systems.

Deterministic voice playback without taxing system resources

In safety-critical applications such as gas stoves, door locks, or maintenance helmets, designers often face limitations on CPU headroom and system responsiveness. Epson’s Voice MCUs solve this with a dedicated hardware processor for audio decoding. Playback requires only a sentence number to be set - no runtime processing burden is placed on the main application code.

For designs requiring quick and reliable voice alerts, e.g. “Caution: grill door is hot” or “Battery low”, this deterministic playback model ensures latency-free delivery without interrupting core logic or safety functions.

Easy integration with ESPER2 and low BOM cost

Voice data preparation is handled through ESPER2, Epson’s intuitive PC-based tool that converts .wav files into highly compressed formats suitable for the ICs' onboard memory or external SPI Flash. Designers can easily create multilingual prompt sets and layer voice with background music or alert tones.

The hardware itself supports:

• Up to 2-channel mixing (e.g. voice and music)

• Volume and playback speed control

• Buzzer and speaker output configurations

• Piezo, electromagnetic, and amplifier support

These ICs are especially attractive for compact or battery-operated products thanks to low current consumption and flexible power options (1.8V to 5.5V). Configurations can be optimised for low space and low BOM cost; ideal for mass-market devices, wearables, and consumer health electronics.

Proven in real-world safety and healthcare applications

Epson’s audio ICs have been adopted in:

• Digital door locks (Japan, Taiwan, Europe) - providing verbal status feedback for visually impaired users

• Infusion and syringe pumps - guiding users with audible instructions to reduce risk of error

• Excavators and transport robots - issuing voice alerts in hazardous industrial environments

• Gas and CO alarms - providing accurate spoken warnings that are less likely to be ignored than tones

For developers with no prior voice implementation experience, the plug-and-play approach of Epson’s Speech LSIs makes them an excellent choice.

Nuvoton Audio ICs – Voice Capture, Processing and Playback for Interactive Systems

For designs that require advanced voice interaction, recording, noise suppression or smart audio routing, Nuvoton offers a deep portfolio spanning voice ICs, audio SoCs, codecs, ADCs/DACs, amplifiers and enhancement DSPs. This makes it possible to construct complete audio pipelines for demanding applications such as intercoms, emergency call boxes, AI voice assistants, or portable speakerphones.

NSP Series – Compact Voice Playback ICs with OTA Update Support

The NSP2.0 series (e.g. NSP2340A) is a standout solution for adding spoken guidance to compact devices. With up to 420 seconds of audio (at 12 kHz), 2-channel playback, and a tiny SOP8 package, these ICs enable clear voice output in appliances like:

• Blood pressure monitors

• Electronic toothbrushes

• Massage chairs

• EV chargers

• Vending machines

Voice prompts are stored in internal flash and can be updated remotely via ISP or OTA, supporting field upgrades. The NSP PlayList Editor Tool provides simple drag-and-drop control over audio content and sequencing.

ISD94xxx – High-performance voice MCU with beamforming and echo cancellation

The ISD94124 series (Cortex-M4F @ 200 MHz, 512 KB Flash) is designed for rich audio interaction and real-time voice processing. Key features include:

• 4x digital microphones (DMIC) input

• AEC + NR + VR algorithms

• USB/I²S bridge and DPWM out for speaker drive

• Far-field pickup, enabling reliable voice command even in noisy environments

It’s ideal for intercoms, smart doorbells, walkie-talkies, and hands-free emergency call systems.

Combined with NAU88C and NAU84xx codecs, and NAU83G class-D amplifiers, Nuvoton enables complete solutions for:

• eCall modules in vehicles (emergency call with voice uplink)

• AVAS systems for EV pedestrian safety

• Smart home assistants and language-learning speakers

• UCS platforms like Zoom/Teams-enabled speakerphones

Bongiovi and MaxxAudio DSPs for rich UX

For designs focused on user engagement and fidelity, Nuvoton integrates Bongiovi DPS and Waves MaxxAudio® technologies into dedicated DSP+AMP combos like the NPCP215F and NPCA121D.

These provide:

• 2x20W Class-D output

• I²S interfacing

• USB support

• Dynamic profile switching (e.g. voice vs music modes)

Whether used in portable speakerphones, soundbars, or industrial UI panels, these audio processors elevate clarity and user experience.

Real-World Applications – Audio as a Safety, Accessibility and UX Enhancer

Across industries, audio ICs are transforming how machines communicate with humans. Whether it's ensuring safety through audible alerts, making devices accessible to visually impaired users, or streamlining interaction in UI-light environments, both Epson and Nuvoton offer proven solutions already in the field.

Health and Assistive Technology

• Infusion pumps and syringe drivers (Epson S1V3G340): Provide clear verbal status updates and alerts in medical devices, reducing dependency on displays and enhancing usability in urgent care settings.

• Blood pressure monitors (Nuvoton NSP2340A): Offer hands-free spoken guidance for home users, including the elderly or visually impaired—no app or screen required.

• Smart toothbrushes and hearing assistance (Nuvoton NSP & NAU88L21): Add spoken timers, usage feedback, and low battery warnings using compact, low-power ICs.

Workplace and Industrial Safety

• Gas stoves and heaters (Epson S1C31D50):Speak out temperature states or warn if doors are left open or safety systems are triggered, even with only an 8-bit MCU in the system.

• Maintenance helmets and excavators (Epson S1C31D50): Deliver danger warnings directly to workers via localised voice playback - even in environments where wireless signals may be unreliable.

• AVAS systems for electric vehicles (Nuvoton ISD94124 + NAU83G60):Provide mandatory external vehicle sound to alert pedestrians, including continuous warning tones compliant with UN R138.01 and FMVSS 141.

User Interfaces with Limited or No Display

• EV chargers and vending machines (Epson S1V3G340 / Nuvoton NSP2080): Use spoken instructions to guide users through payment or connection steps when screen real estate is limited.

• Voice command lamps, remotes and smart home panels (Nuvoton ISD9160 / ISD94124): Enable natural language input with localised processing and noise suppression.

• Intercoms and call boxes (Nuvoton ISD94124S): Provide clear bidirectional audio with echo cancellation and voice recognition, essential in emergency installations or remote buildings.

These examples highlight how accessible, embedded audio isn't just a 'nice-to-have' - it's becoming essential in the pursuit of safer, more inclusive, and more intuitive embedded systems.

Key Specifications and IC Selection Overview

Whether you need a compact playback-only voice prompt IC, or a complete audio front-end with processing, recording and smart amplification, both Epson and Nuvoton provide a clear range of choices suited to embedded environments. Below is a snapshot of their key offerings:

Epson Voice/Audio IC Overview

Part Number	Type	Flash / RAM	Output Options	Key Features
S1C31D50/51/41	Voice MCU	Up to 192KB / 10KB	Speaker / Buzzer (4 configs)	HW processor for voice, ultra-low power, 2ch mix
S1V3G340	Speech LSI	30s–80s SoundROM	SPI Flash, Speaker	SPI/UART/I²C, minimal integration effort
S1V3F351/352	Speech LSI	Ext. Flash up to 16MB	Speaker	Streaming playback, 2ch mix, buzzer & melody support

• All Epson ICs support high-compression EOV format, ESPER2 voice creation tool, and multi-language prompt handling.

• Playback can be initiated via serial interface or pin trigger, ideal for low-MCU-load applications.

Nuvoton Audio IC Family Overview

Category	Key Parts	Functionality
Voice ICs	NSP2080 / NSP2340A	80–420 sec voice, 2ch playback, <1 µA standby, OTA update
Voice SoCs	ISD94124S / ISD9160 / ISD933H3	NR + AEC, 200MHz Cortex-M4F, DMIC support, DPWM, USB
Codecs	NAU88C22 / NAU88L21 / NAU8820	HiFi stereo, low THD+N, headset detect, SR up to 192kHz
ADCs / DACs	NAU8502 / NAU8421 / NAU8401	Low latency, 128dB SNR, auto clock detection
Amplifiers	NAU83G10 / NAU83G20 / NAU83G60	Class-D, 10–60W, PEQ/DRC, I²S/TDM interfaces
DSP+AMP Combo	NPCP215 (MaxxAudio) / NPCA121D	Bongiovi or Waves DSP, stereo output, 2x20W class-D

This flexibility allows Nuvoton solutions to cover both embedded safety speech feedback and advanced UX audio, including voice recognition and full stereo output.

Conclusion – Smarter Interaction, Safer Systems with Embedded Audio

From safety-critical alarms to intuitive voice guidance in smart appliances, embedded audio is becoming indispensable in modern electronics design. By integrating clear, context-aware voice prompts, engineers can reduce reliance on screens, enhance accessibility, and meet new safety requirements—without adding excessive system complexity.

Epson’s speech ICs and voice MCUs offer a clean, cost-effective route to deterministic voice playback, particularly suited for white goods, medical devices, and low-power applications. In contrast, Nuvoton’s portfolio empowers more sophisticated systems—enabling noise-suppressed far-field pickup, dynamic audio routing, and rich amplification for everything from eCall modules to speakerphones and interactive kiosks.

For embedded developers and product engineers, this diverse toolkit means one thing: audio can now be designed in from the start, not bolted on at the end.

Looking to explore the right audio IC for your product?

Contact Ineltek today to discuss sample availability, system design support, or to request datasheets for any of the Epson or Nuvoton parts featured.