How close should the microphone be when you dictate?

Keep a headset microphone about an inch from the side of your mouth, and keep a handheld microphone 1 to 3 inches from your mouth, not directly in front of it. Those are the placements that Nuance gives for its Dragon dictation software. The reason is physics. Under ideal conditions, a sound level drops by about 6 dB each time the distance doubles ¹, so the microphone that sits a foot away receives a much weaker voice than one an inch away.

A headset belongs about an inch from the side of your mouth

For a headset, Nuance's Dragon guidance is to keep the microphone element about an inch from the side of your mouth, but not touching it ². The placement is about the side of the mouth, not directly in front, which is the position we use in the test below. A headset that slides or drifts changes that distance, so check its position at the start of each session.

These are instructions from one software maker, not a universal standard. We did not find an independent standard for dictation microphone distance, so treat the one-inch figure as a practical target, and measure your own results against it.

A handheld microphone works at 1 to 3 inches, not directly in front

For a handheld microphone, Nuance's guidance is to keep the element 1 to 3 inches from your mouth, not directly in front ³. A handheld microphone gives you more room to move than a headset, and that movement is the problem. If your hand drifts, the distance changes, and so does the signal.

Doubling the distance costs about 6 dB, and the first inch matters most

Under ideal conditions, with no reflections or background sound, a sound level drops by 6 dB for every doubling of distance from the source ¹. Applying that rule to a microphone at 12 inches instead of 1 inch gives a level difference of about 21.6 dB ⁴. That figure is a calculation under ideal free-field conditions, so a real room will differ, but the direction is the same: a microphone that moves away from your mouth loses voice level quickly.

The effect shows up in recognition. Ravanelli and colleagues recorded read sentences with a close-talking studio microphone and got a word error rate of 3.7% ⁵. Their distant-microphone result was higher, and the authors state that recognition is dramatically reduced for distant speech compared with the close-talking case ⁶. The study is a 2017 preprint with a 2017 recognizer, so the numbers show the size of the effect rather than a forecast for your setup.

Researchers treat distance as a variable in its own right. In 2016, Prasad and Sim built a far-field speech corpus by re-recording Wall Street Journal audio with microphones at eight distances from the source ⁷. Distance is a problem the research takes seriously, so the placement advice matters.

It depends on the microphone type and what moves

A headset held in one place is the most dependable. A handheld microphone works only if you keep it still and steady. A built-in laptop microphone is set by where the laptop sits, so it is often farther away than any headset, and that is why it struggles in a noisy room. Nuance also tells Dragon users to dictate with a consistent speed and volume ⁸, which is easier to hold when the microphone stays in place.

Two movements change the distance without you noticing. Turning your head to look at a screen moves the mouth away from a boom microphone, and leaning back in a chair moves the mouth away from a desk microphone. Keep the microphone fixed to your head or the desk, not to the screen.

What to do

1. Put a headset about an inch from the side of your mouth, not touching it, and mark or note where the boom sits so you can return to it.
2. Put a handheld microphone 1 to 3 inches from your mouth, not directly in front of it, and keep it there for the whole session.
3. Read a fixed passage of about 100 words at your normal volume, and count the wrong, missing and extra words. Then move the microphone 6 inches farther away and read it again.
4. Keep the placement that gives the lower error count, and note the position so you can repeat it.

The full method, including how to choose between a headset and a built-in microphone, is in the guide to the best microphone for dictation. The laptop microphone question covers the built-in case, and the wireless headset question covers the Bluetooth case. For what word error rate means, see the glossary entry. The dictation series page lists every guide in the series.