Understand What Headphone Firmware Controls
Firmware is the control program stored inside the headphone chipset. It tells the headphones how to respond when a user performs an action.
For example, firmware decides what happens when a user presses and holds a button. It also controls how the headphones enter pairing mode and reconnect after losing a connection.
For headphones with ANC or transparency mode, firmware usually controls the order of these listening modes. Low-battery warnings and automatic power-off settings are also controlled by firmware.
The same housing and chipset can run different firmware. As a result, two samples that look identical can behave differently.
When buyers approve headphone firmware, they are approving the way the product operates. They are not simply approving a file name.
Record the Exact Approved Firmware
Writing “Firmware V1.0 approved” in an email is not enough.
V1.0 is only a name. Two files created at different times can use the same name while containing different settings.
A clear approval record should connect the firmware file with the sample number, firmware version and file date. It should also state which product functions are included in that version.
Buyers can also ask the supplier for the file checksum. A checksum works like a digital fingerprint. When the contents of the firmware file change, the checksum also changes.
The Bluetooth Qualification Program Reference Document includes hardware and software version information as part of product identification. This shows why the software version should not be treated as an unimportant internal note.
Test the Headphones in Real Use
Firmware approval should cover every function promised in the product specification or packaging.
| Area | What the buyer should confirm | Evidence to keep |
|---|---|---|
| Buttons and touch controls | What happens after a single press or long press | Control table and approved sample |
| Bluetooth connection | How the headphones pair and reconnect | Connection test record |
| Listening modes | How ANC and transparency mode are switched | Mode list and listening result |
| Voice prompts | Which prompts are used and when they play | Prompt list and approved sample |
| Power management | How low-battery warnings and automatic power-off work | Test result |
| Companion app | Whether the app can identify and update the headphones | Compatibility record |
There is no reason to test a function that the product does not support. However, every function shown in the specification or marketing materials must work on the approved sample.
Testing should begin with the headphones restored to their original settings. The tester should complete the first pairing and then turn the headphones off to check automatic reconnection.
If the headphones support calls, the tester should also check what happens when a call interrupts music. After the call ends, the headphones should return to music playback as agreed.
The target devices must be decided before testing. If the product claims to support both phones and computers, connection tests should cover both device types.
Successful pairing with one engineer’s phone does not prove that the required device compatibility has passed.
Lock the Production Firmware Before Manufacturing
After firmware testing is complete, the supplier should prepare the final production file. This file must match the approved sample and its test record.
The buyer does not always need the firmware source code. Source code is the original program used by developers to modify the firmware. Whether it is provided depends on the project agreement.
However, the buyer must know which firmware version will be used for production. The supplier must also be able to connect that version to the approved sample.
Before programming the full production batch, the supplier should confirm the firmware file and programming settings. Programming means writing the firmware into the headphone chipset.
The supplier should then program one unit first. The firmware version and main product operations of this first unit should be compared with the approved sample.
If the version or product behavior does not match, programming should stop. Production should continue only after the problem has been corrected and the first unit has passed another check.
Checks during the first production batch help confirm that the approved firmware is being written consistently. These checks cannot replace firmware approval before production.
Review Every Firmware Change Before Use
The supplier should not replace approved firmware without recording the change. Every new version should explain what was changed and which functions require another test.
If only a voice prompt changes, the prompt content and playback timing should be checked again.
If the Bluetooth connection settings change, pairing and automatic reconnection should be retested. A power-management change requires another check of battery warnings and battery life.
When ANC settings change, the supplier should compare the noise reduction and sound performance with the approved sample.
A firmware change does not automatically mean that the product must repeat every certification process. However, if the change affects the Bluetooth design or a declared configuration, the brand should confirm whether the existing qualification still applies.
The Bluetooth SIG qualification guidance explains that Bluetooth products must complete the applicable qualification process before they are sold or distributed.
Do not use changed firmware for production until its effect has been reviewed.
Agree on Firmware Support Before Launch
Compatibility issues or new product requirements can appear after a product enters the market. The brand and supplier should therefore agree on who records problems and who prepares updated firmware.
If users can update the headphones, the update method should also be confirmed. The project team should know what happens when an update fails and how the product can be restored.
For products sold in the European Union, the brand should also check whether the product falls within the scope of the Cyber Resilience Act.
For products within its scope, the European Commission guidance for manufacturers explains the manufacturer’s responsibilities for handling vulnerabilities during the support period and reporting relevant incidents.
This does not mean that every headphone project has the same obligations. The responsible company must evaluate the product functions and its role in placing the product on the market.
For OEM buyers, firmware approval is more than confirming a version number. Buyers need to know how the headphones will work and whether mass-produced units will follow the same approved settings.
When discussing a headphone project with Sonun, buyers can provide their target devices, required controls and sales markets. They can also confirm the required voice-prompt languages. These details can then be connected to the firmware version, test results and approved sample.
Do not approve full mass production until the approved firmware and production file clearly match.
