Quick fix: Bluetooth headsets use Hands-Free Profile (HFP) for calls — mono, 8kHz, sounds tinny. To force higher quality: open Sound Control Panel (mmsys.cpl) → Recording tab → pick headset mic → Properties → Advanced → pick 16-bit, 44100 Hz Stereo (or higher). Or disable Hands-Free Telephony service: Services.msc → Bluetooth Audio Gateway Service → Disable. Headset uses A2DP only; better audio quality, no microphone during calls.

Bluetooth headsets have two profiles: A2DP (high-quality stereo audio output only) and HFP (low-quality bidirectional for calls). Switching to HFP during calls causes tinny sound. Trade-off: stay on A2DP for quality but lose mic, or use HFP and accept tinny audio.

Symptom: Bluetooth mic sounds tinny during calls on Windows 11.
Affects: Windows 11 with Bluetooth headsets.
Fix time: ~10 minutes.

What causes this

Bluetooth audio profiles:

A2DP (Advanced Audio Distribution Profile): high-quality stereo. Output only. ~250kbps.
HFP (Hands-Free Profile): bidirectional. Mono, 8kHz, ~64kbps. Sounds tinny.
aptX / LDAC: alternatives to A2DP. Better quality. Not for mic.

Calls require bidirectional audio = HFP. No HiFi BT mic profile widely supported until recent (Le Audio).

Method 1: Use LE Audio if supported

The modern solution.

LE Audio (Bluetooth Low Energy Audio) is the new standard with stereo + mic at high quality.
Requires: PC with BT 5.2+ supporting LE Audio, headset with LE Audio support.
Windows 11 22H2+ supports LE Audio natively.
For checking: Settings → Bluetooth & devices → pick headset → Properties. If LE Audio listed: enabled.
For older headsets: no LE Audio. Use Method 2.
For Microsoft Surface Earbuds, newer Bose / Sony: LE Audio support.
For chronic HFP issue: get LE Audio headset.

This is the modern fix.

Method 2: Use USB receiver / dongle

For non-LE Audio headsets.

Many gaming headsets ship with USB receivers (Logitech G Pro, SteelSeries Arctis, etc.).
USB receivers use proprietary 2.4GHz protocol, not Bluetooth.
Result: stereo high-quality + mic high-quality simultaneously.
For Bluetooth-only headphones: get a USB Bluetooth dongle that supports aptX HD or LDAC. Some support better mic.
For dedicated mic: use desk mic + Bluetooth headphones for audio out. Mic input separate from audio output.
For business calls: USB headset (Jabra Evolve, Plantronics) gives consistent quality.
For Apple AirPods Pro / Max: Windows treats as standard BT. HFP issue applies.

This is the workaround.

Method 3: Adjust microphone settings

For tweaking within HFP limits.

Open mmsys.cpl. Recording tab.
Find Bluetooth headset (HFP) mic. Properties → Advanced tab.
Default format: usually 16-bit, 8000 Hz Mono.
Try higher: 16-bit, 16000 Hz Mono. Some headsets support.
For wideband HFP: 16kHz instead of 8kHz. Improves but still tinny vs A2DP.
For Microsoft Teams: Settings → Devices → pick correct mic. Teams may use different mic.
For Zoom / Discord: pick the headset mic explicitly.
For chronic: ensure latest BT driver. Realtek / Intel BT.
For Bluetooth advanced settings: Device Manager → Bluetooth → right-click headset → Properties → Advanced.

This is the tweak route.

How to verify the fix worked

Mic audio in calls sounds better.
Recipients report clearer voice.
Settings show Wideband or LE Audio for mic if available.
Sample rate higher than 8kHz.

If none of these work

If tinny persists: HFP is the bottleneck: standard limit ~8kHz. Inherent. For BT older than 5.0: no wideband HFP. Replace adapter. For specific app integration: Teams / Zoom may force specific profile. Configure in app. For Microsoft 365 Audio Conferencing: server-side audio processing. Mic quality determined at endpoint. For specific Bluetooth chipset: Intel AX210 / AX211 better than older. For Skype quality: Skype prioritizes voice clarity over fidelity. May sound tinny inherently. For pro use: dedicated USB headset or external USB mic. Bluetooth not ideal for voice quality.

Bottom line: HFP profile inherently tinny (8kHz mono). Get LE Audio headset for modern hi-fi BT calls. Or use USB headset / dongle for high-quality bidirectional. Tweak sample rate in mmsys.cpl → Advanced if device supports.