Bluetooth headphones are built for listening to music, not for dictation. Their microphone works, but only in a mode designed for phone calls. That costs accuracy, sometimes swallows your first words and makes your music sound like a phone call. That is why Sprecho does not use a Bluetooth microphone on Automatic, and why other dictation apps also recommend the built-in microphone.
Why Bluetooth is worse for dictation
A Bluetooth headset has two modes:
- Music mode (A2DP): high-quality playback, but no microphone.
- Call mode (HFP): microphone and sound at the same time, both in phone quality.
It cannot do both at once. The moment an app opens the microphone, the headset has to switch to call mode. Three things follow:
- The switch takes time. We measured about 0.4 seconds on AirPods Max; other headsets take one to two seconds. If you start speaking straight away, the first words are lost, or the first moment of the recording is silent.
- The audio is built for phone calls. Narrow bandwidth, heavily compressed, plus the headset's own noise suppression. Recognition gets measurably worse, and names and technical terms suffer first.
- Your music suffers too. While the microphone is open, everything in the headset sounds like a phone call. AirPods may also switch over from your iPhone to your Mac.
Keeping the microphone open permanently would remove the delay, but your headset would then stay in call mode all day. That is why Sprecho does not do it.
The newer Bluetooth LE Audio may improve this in future, but it is still rare today.
What Sprecho does automatically on your computer
Under Settings → General → Input Device, and in the microphone picker on the macOS menu-bar icon or the Windows tray icon, you get Automatic plus every connected microphone.
Automatic uses your computer's default microphone, unless it is a Bluetooth device:
| System default | What Sprecho records with |
|---|---|
| Built-in microphone | Built-in microphone |
| USB headset, USB microphone, dictation microphone | That device |
| Microphone in a dock or monitor | That device |
| AirPods or another Bluetooth headset | Built-in microphone, or else a wired one |
So your AirPods stay headphones at full quality, and Sprecho listens through a microphone that is recognised better.
Using Bluetooth anyway
There are good reasons to, such as occasional dictation on the go, or a noisy open-plan office where a microphone close to your mouth matters more than audio quality. Here is how:
- Open Settings → General → Input Device, or click the Sprecho icon in the menu bar or tray.
- Select your headset explicitly. In Settings, a short hint about Bluetooth quality appears below it.
- Press the dictation key, wait about half a second, then speak.
What happens then:
- Sprecho opens the Bluetooth microphone only while you are dictating, never while idle.
- Starting takes roughly half a second, because the headset has to switch modes.
- Music in the headset drops to call quality during the recording and comes back afterwards.
- If the Bluetooth microphone stays silent or disappears, Sprecho records that dictation with the built-in microphone and tells you in a notice. When the headset is back, Sprecho automatically returns to your choice between dictations.
On your phone
The Sprecho app also records with the phone microphone by default. On Android, choose Bluetooth headset under Settings → General → Microphone; on the iPhone, switch on Use AirPods microphone. Details in Choose the right microphone.
Problems and fixes
| What you notice | Why | What helps |
|---|---|---|
| The first words are missing | The headset is still switching to call mode | Wait half a second after pressing the key, or use a wired microphone |
| Recognition is poor, names come out wrong | Phone quality and the headset's noise suppression | Select the built-in or a wired microphone |
| Music sounds like a phone call while dictating | The microphone is open, the headset is in call mode | Normal, it comes back after the dictation. Only avoidable without a Bluetooth microphone |
| AirPods jump from the iPhone to the Mac | Opening the microphone on the Mac pulls the AirPods over | Set Input Device to Automatic, then the AirPods microphone stays closed |
| Notice that another microphone is being used | The headset was silent or unreachable | Nothing to do, Sprecho switches back as soon as it is available again |