Treating a room for recording an audiobook at home

What the problems are

• Reflections. The voice reaches the microphone directly, and a few milliseconds later again off the walls and the desk. The reflected sound makes a recording hollow and distant, the “bathroom” sound. It is the most common problem in home recordings and the easiest to fix.
• Background noise. A refrigerator, a computer fan, traffic, a furnace and the neighbors are recorded along with the voice. Treatment inside the room does little against noise from outside it; the remedies are the quietest room at the quietest hour, and sealing the gaps that let sound in.
• Low-frequency rumble and boom. Small rooms add a boomy build-up in the low frequencies, strongest in the corners, and traffic and heating add a rumble below the voice. Bass traps reduce the build-up; a low-cut filter on the microphone or interface removes most of the rumble.

Treatment before equipment

A treated room improves every microphone, and an untreated room limits every one of them. The most effective changes cost nothing: record in the smallest, softest room in the house, away from windows and appliances, with the microphone a hand’s width from the mouth. A walk-in closet full of clothes is a good booth as it is.

Hard, parallel surfaces are the problem. Soft, thick materials close to the microphone and the reader are the solution: the nearer the treatment is to the reading position, the more it does.

Under $100

A closet or a few blankets, and a reflection filter, remove most reflections for the price of a microphone accessory.

sE Electronics Reflexion Filter X

Our pick Reflection filter Mounts on a stand About $90 to $100

A curved shield that mounts on the stand behind the microphone. It absorbs part of the voice that would otherwise reach the wall in front of you and bounce back into the microphone. It is light, folds flat for storage and fits any standard stand. Manufacturer’s website

It treats what is behind the microphone. The wall behind the reader still needs a blanket or a panel.

Check the price on Amazon

Moving blankets

Absorption Do it yourself About $45 for six

Heavy quilted blankets, hung from a curtain rod, a clothes rack or a frame of PVC pipe on both sides and behind the reader, make a small booth for little money. They absorb the mid and high frequencies of the voice that cause the hollow sound of a bare room.

The thicker the blanket, the better. A thin blanket stops the top end and nothing else. U-Haul sells a pack of six for about $45, and hardware and discount stores sell them singly.

Under $300

Studio panels on the walls nearest the reader, or a larger reflection filter for a room where nothing hangs on the walls.

ATS Acoustics acoustic panels (24 x 48 x 2 in)

Our pick Absorption Wall panels About $90 to $110 each

Fabric-wrapped panels of dense mineral wool, made for studios, that absorb far more than foam of the same thickness. Two or three panels, one behind the reader and one on each side at head height, remove most of the reflections a home room adds to a voice. Manufacturer’s website

Hang them as close to the reading position as the room allows. A panel across the room does much less.

Check the price at ATS Acoustics

Aston Halo Shadow

Reflection filter Mounts on a stand About $300 to $350

The all-black version of the Halo, a larger and deeper reflection filter than the Reflexion Filter X. Its molded PET felt wraps further around the microphone, above it and below it as well as at the sides. It treats more of the space around the microphone and suits a room where panels cannot be hung. Manufacturer’s website

Like any reflection filter, it leaves the wall behind the reader untreated. The purple Halo and the white Halo Ghost are the same filter in other colors.

Check the price on Amazon

Under $1,000

A treated corner with bass traps, or a folding booth that travels. A walk-in blanket booth, such as the VocalBoothToGo Audio Booth 3, costs about $1,000 from its maker and is the next step up.

ATS Acoustics Corner Bass Trap

Our pick Bass trap Corner mount About $210 each

A thick, five-sided absorber, 24 by 48 inches and 13 inches deep, made to fit into the corner of a room where low frequencies build up. Two traps in the corners nearest the reading position reduce the boomy, boxy sound a small room gives a deep voice. Manufacturer’s website

The traps are made to order and ship in a few days. A treated corner, two traps and three or four panels, comes to about $700 to $850 in total.

Check the price at ATS Acoustics

Harlan Hogan Porta-Booth Pro

Desktop booth Folds into a case About $450

A folding desktop booth lined with acoustic foam that surrounds the microphone on five sides, designed by a voice-over artist for recording away from a studio. It sets up on a table or a stand in a few minutes and packs into its own case. Manufacturer’s website

The reader’s head stays outside the booth, so the wall behind still matters. It suits a small dynamic or condenser microphone.

Check the price at Voice Over Essentials

Sealing out noise

• The door. A door sweep or a strip of weatherstripping around the frame closes the gaps that let most household noise into a room. A solid door blocks far more than a hollow one.
• The window. A heavy blanket or a removable panel over the window during sessions reduces traffic noise. Closing the curtains helps a little.
• The house. Turn off the refrigerator, the furnace, air conditioning and fans while recording, and turn them back on afterwards. Move the computer out of the room, or as far from the microphone as the cable allows.

The noise print, and what cannot be fixed afterwards

Ten seconds of silence before a session give StellAurator a picture of your room’s steady sound, and the noise reduction uses it to tell that sound from the voice. The room’s live noise is drawn beside the saved print, so a fan switched on since shows before you record.

Steady noise, a fan or a hum, comes down afterwards. A sound under the voice does not come out cleanly: a dog barking or a door closing during a line stays in the recording, and the line is recorded again. In StellAurator such a line is marked for a pickup. Reflections do not come out afterwards either, and so treatment comes first.

For the levels ACX measures, including the noise floor, see Audible’s ACX audio requirements, explained. For a microphone that picks up less of the room, see the microphone guide.