EZB Audio Playback Issues

Synthiam ARC supports real-time audio streaming to compatible EZ-B controllers, allowing sound generated on your computer to be played directly through the EZ-B’s onboard audio hardware. When configured correctly, this delivers smooth, responsive audio for speech, sound effects, and interactive robot behaviors. However, if you experience audio skipping, looping, or stuttering, the cause is almost always related to how digital audio is streamed and how wireless interference affects that stream.

How ARC Audio Streaming Works

To understand why audio can skip, it helps to know how ARC and the EZ-B handle audio internally.

Audio generated by Synthiam ARC is transmitted to the EZ-B as a continuous stream of digital packets. These packets arrive over the active connection (typically Wi-Fi) and are written to a continuous Direct Memory Access (DMA) buffer inside the EZ-B. The EZ-B’s digital-to-analog converter (DAC) continuously reads from this buffer and converts the digital samples into analog audio output.

Under ideal conditions, new audio data arrives fast enough to keep the buffer filled with fresh samples. The DAC reads smoothly from the buffer, resulting in uninterrupted audio playback.

Problems occur when the flow of audio packets is interrupted.

Why Audio Skips or Loops

When Wi-Fi interference, congestion, or packet loss occurs, audio packets may arrive late or not at all. The DAC does not stop when this happens—it continues reading from the DMA buffer at a fixed rate. If new audio data has not yet replaced the old data in the buffer, the DAC loops over the existing samples.

This behavior causes the most common audio symptoms:

  • Repeated words or sounds
  • Short looping audio fragments
  • Stuttering or choppy playback
  • Audio that briefly freezes before continuing

Importantly, this is not a software bug in ARC or a hardware failure in the EZ-B. It is the expected behavior of a real-time audio system that depends on uninterrupted packet delivery.

Common Causes of Audio Interference

Several factors can interfere with reliable audio streaming:

  • Busy or congested Wi-Fi channels
  • Nearby routers using overlapping channels
  • Microwaves, cordless phones, or other 2.4 GHz devices
  • Long distance or weak signal strength
  • Multiple devices connecting to the EZ-B’s access point
  • Accidentally modified EZ-B firmware settings

Any of these conditions can introduce enough packet delay or loss to cause audible skipping.

Recommended Solutions

1. Use a Wired Connection When Available

If your EZ-B model supports a hardwired USB or UART connection, this is the most reliable solution. A wired connection eliminates Wi-Fi interference and ensures consistent packet delivery for audio streaming.

Wired connections are especially recommended for:

  • Robots used in classrooms or public spaces
  • Environments with many Wi-Fi networks
  • Projects that rely heavily on speech or continuous audio

2. Scan for a Clear Wi-Fi Channel

If you are using Wi-Fi, scan for available channels using a Wi-Fi analyzer on your computer or mobile device. Look for a channel with minimal overlap and traffic.

Some EZB controllers are connected via WiFi, such as the ESP32, EZ-Robot IoTiny, and EZB v4. While WiFi is convenient because it doesn’t require wires, it is the second most common cause of issues, next to brownouts due to lower power. The WiFi connection should operate on a channel that is not saturated, providing the greatest stability and throughput.

*Note: We recommend using a USB EZB connection rather than WiFi for robots in production environments.

  • Check for the WiFi channel saturation? Use THIS TOOL to check and switch to a less saturated channel. If possible, consider hardwiring the EZB to the PC.

Download the WiFi Scan Tool (WifiInfo.exe)

Once a clear channel is identified, update the EZ-B’s Wi-Fi settings to use that channel. Reducing channel congestion can dramatically improve audio reliability.

3. Connect the EZ-B to Your Local Network

Instead of running the EZ-B as a standalone hotspot, consider connecting it to your existing local Wi-Fi network. When the EZ-B is part of your main network:

  • Signal strength is often better
  • Your router manages channel selection
  • Interference is reduced compared to ad-hoc hotspots

This configuration is strongly recommended for home labs, classrooms, and workshops.

4. Secure the EZ-B Wi-Fi Network

Always set a password on the EZ-B’s Wi-Fi network. Open networks attract nearby devices and people searching for free internet access. Even though the EZ-B does not provide internet routing, it still must handle connection attempts and network traffic from every client that connects.

Excessive connection attempts consume processing time and wireless bandwidth, increasing the likelihood of dropped audio packets.

A password-protected network ensures that only your ARC instance is communicating with the EZ-B.

5. Reset the EZ-B to Factory Settings

Firmware settings can sometimes be changed unintentionally during testing or experimentation. If audio issues suddenly appear and no obvious environmental cause is apparent, resetting the EZ-B to its factory configuration is a good troubleshooting step.

Pressing the RESET button on the EZ-B restores default firmware settings, clears accidental misconfigurations, and often resolves unexplained behavior.

Additional Best Practices

  • Keep the EZ-B within a reasonable range of the Wi-Fi source
  • Avoid placing the EZ-B near large metal objects or enclosures
  • Minimize other high-bandwidth Wi-Fi activity during audio playback
  • Ensure your computer running ARC has a stable network connection

Real-time audio streaming is inherently sensitive to network conditions. By reducing interference and ensuring consistent packet delivery, you can achieve smooth, reliable audio playback from your EZ-B.