Recording good audio for interviews: why sound matters most

A documentary or testimonial interview lives on what people say. If the words are hard to hear, the story is lost, however beautiful the picture. In our own practice, we treat sound as the part of an interview that is hardest to repair later: a soft image can often be reframed or graded, but traffic, echo or a rustling microphone recorded underneath a voice usually stays there.

Good audio for video interviews is also an accessibility issue. The W3C notes that people who are hard of hearing often have great difficulty separating speech from background sound.¹ Its guidance for audio-only content sets a useful benchmark: background sounds should be at least 20 decibels lower than the foreground speech, which is roughly four times quieter.¹ That criterion is written for audio-only recordings, but it is a sensible target for any interview, including films where music is added in the edit.

Good interview audio starts before anyone touches a microphone. Choose the location for its sound as well as its look. CapRadio's guide advises seeking out the quietest spot you can find in a noisy setting, and positioning your subject so the microphone is aimed away from the noise source.²

NPR Training's checklist is worth running through on arrival: turn off the air conditioning, close the windows, make sure nobody is vacuuming, and unplug noisy appliances such as the fridge.³ It lists a dampened, furnished room as a good set-up.³ In our experience, bare walls, tiled floors and glass produce echo, while curtains, sofas and rugs soften it. That often means choosing a quieter office over the striking glass meeting room, and filming the views separately as cutaways.

For most seated interviews, a small clip-on lavalier microphone does the main work. Shure notes that a lavalier generally sits near the chest, with the ideal spot depending on clothing and production needs.⁴ On a shirt or blouse it advises placing the microphone above the sternum and running the cable discreetly inside; with a tie, keep the cable hidden behind it; on a T-shirt or jumper, fasten it to the collar with minimal friction against the neck.⁴ Dartmouth's guidance gives a simple reference point: on a shirt, above the third button from the top.⁵

Clothing causes most lavalier problems. NPR Training lists rustling clothing, finger tapping, desk bumps, squeaky chairs and jewellery as noises to listen for.³ Dartmouth notes that clothes with no pockets, such as dresses, make a lavalier inconvenient to use, because the transmitter needs somewhere to go.⁵ Ask interviewees in advance what they plan to wear, and suggest they avoid stiff, noisy fabrics and necklaces that swing near the microphone.

Lavaliers come in two main pickup patterns. Omnidirectional models capture sound from all directions and suit speakers who often turn their heads, while cardioid models prioritise sound from the front and reduce noise from the sides and rear.⁴ Wireless models give freedom of movement through a bodypack transmitter, while wired ones are valued for their simplicity and reliability.⁴

With a handheld or boom microphone, distance is everything. CapRadio recommends about 4 to 6 inches, roughly 10 to 15 centimetres, from the interviewee's mouth, aimed from a slight angle below or to the side to reduce plosives, the pops on p and b sounds.² Louder speakers need a little more distance and softer speakers a little less.² NPR Training adds that a close microphone helps avoid room reverberation, suggests aiming at the corner of the mouth, and stresses keeping the distance steady.³

In our own practice, we usually record two sources at once: a lavalier and a boom or camera microphone as a backup. If one picks up a rustle or a wireless drop-out, the editor still has a usable version of the answer.

Set levels while the interviewee speaks at their normal volume, for example by asking them to describe their morning. CapRadio's sweet spot is peaks in the range of -6 to -9 dB.² Levels that run too high cause distortion, and levels that run too low have to be amplified later, which raises the noise floor along with the voice.²

Always listen. NPR Training recommends over-ear headphones and a test recording before the interview begins.³ Turn off alerts and ringers on every device, switch on Do Not Disturb, and if an interruption does happen, re-record the answer.³ Small human details matter too: make sure the interviewee has water, and NPR notes that apple juice can help with mouth clicks.³

For file settings, CapRadio prefers WAV at 44,100 Hz, mono, 16-bit for its radio work, and points out that audio from NPR and many other sources uses 48,000 Hz, so files may need converting.² For a film, agree one sample rate with your editor before the shoot and set every recorder to match it.

Before you leave, record the silence. CapRadio advises recording 30 to 60 seconds of location sound with no one talking, before or after the interview, without changing the record levels.² NPR Training likewise suggests pausing for a moment of silence while still recording.³ Ask everyone in the room to stay still. That room tone lets the editor fill gaps and smooth cuts so the background does not jump between sentences.

In the edit, keep the voice clearly above any music or atmosphere, using the 20 dB benchmark as a guide.¹ For broadcast, the European Broadcasting Union's R 128 recommendation sets an average programme loudness of -23 LUFS.⁶ Check which loudness standard the broadcaster or platform requires, and listen back on both headphones and an ordinary phone speaker before you approve the final mix.

• Quietest room chosen, with air conditioning off and windows closed
• Fridges and other noisy appliances unplugged
• Interviewee advised on clothing and jewellery
• Lavalier above the sternum, cable hidden, nothing rubbing
• Backup microphone recording at the same time
• Peaks set around -6 to -9 dB, with headphones on throughout
• All phones on Do Not Disturb
• 30 to 60 seconds of room tone recorded