My Internal Mic Is Not Working

[Kronos_7962]

Internal microphone not detected — Intel SST OED fails with Code 10, "FW did not sent FW Ready notification"

System: HP EliteBook 840 G8 Notebook PC, i7-1185G7, 32 GB RAM
BIOS: T37 Ver. 01.24.02 (released 05/04/2026, installed on my machine 07/07/2026)
OS: Windows 11 24H2, build 26100

Problem

The built-in microphone is not detected at all — no input device appears in Sound settings. Speakers and headphone output work perfectly. It worked until recently.

The root cause appears to be the Intel audio DSP failing to load its firmware. In Device Manager, under System devices:

Intel® Smart Sound Technology OED — This device cannot start. (Code 10)
FW did not sent FW Ready notification.

Matching System event log entries, repeating on every boot:

Provider: Intel-SST-OED   Event ID: 17
Initialize DSP Firmware. Failed to load FW. FW not ready,
STATUS = Unknown NTSTATUS Error code: 0xef000000

followed by Service Control Manager 7024 — The Intel(R) Audio Service service terminated.

Because OED won't start, its child devices never enumerate. Get-PnpDevice shows:

OK       System         Intel® Smart Sound Technology BUS
Error    System         Intel® Smart Sound Technology OED
Unknown  MEDIA          Intel® Smart Sound Technology for Digital Microphones
Unknown  AudioEndpoint  Microphone Array (Intel® SST for Digital Microphones)

Already tried, without success

• Windows mic privacy settings — all enabled
• Show hidden/disabled devices in Sound and Device Manager — nothing disabled
• BIOS (F10) → Advanced → Built-in Device Options — Microphone and Audio Device both enabled
• Full cold power drain (shutdown, charger removed, power button held 15 s)
• Clean reinstall of HP's current audio package, sp174165, Realtek HD Audio Driver 15.10016.9947.98 Rev.Q (Aug 18, 2026) via install.cmd — all components installed successfully (IntelHDASST, Intel OED extension, Realtek base + extension, SRapo, FMomg), followed by reboot. No change.
• Uninstalled and reinstalled the OED device several times — returns with the same Code 10 immediately
• HP PC Hardware Diagnostics UEFI (2.3.8.0) → System Board Test: PASSED, including Audio: PASSED (Pass ID recorded)

Note on driver versions: the Intel SST base drivers (intcoed.inf, intcaudiobus.inf, intcdmic.inf) are all 10.29.0.9947 dated 10/13/2023, while the Realtek digital-mic extension INFs installed by Windows Update are 9.21.3690.774 dated 07/14/2026. I don't know whether that gap is significant, but the failure began around that period.

Attempted BIOS/ME update

I tried to install sp174021 (BIOS 01.25.00 Rev.A, which also carries Intel CSME firmware 15.56.28.34, up from my 15.55.27.51). The HP Firmware Update utility listed both as "Update" and restarted, but the machine then sat on the HP logo for over an hour without progressing. I force-powered off; it booted normally and the BIOS is still 01.24.02, so the update never applied.