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Improving home studio acoustics for voiceover talents

Due to the overall situation caused by the COVID-19 crisis, many productions that require voiceover recordings are now made remotely. This means that voiceover talents work from their home studios, streaming the audio through technologies such as Source Connect or similar to the end studio, or simply recording the audio files and sending them later.

Many voiceover talents work this way for the first time, and due to the lack of technical knowledge, these days whe hear productions with an inferior sound quality. Typically, this is caused by inadequate acoustics in their recording environment.

Assuming that the equipment met some minimum requirements (microphone, audio interface), and that there are no major issues regarding external sounds (traffic, noise inside the house or from the neighborhood), the biggest challenge in a home recording is room acoustics.

In an untreated room, we usually suffer from an excessive “room sound”, due to the fact that sound bounces off the walls and these multiple reflections cause reverberation. Sound behaves as light: it spreads in all directions, and the reflecting surfaces (walls, floor, ceiling…) act as mirrors. This set of reflections generate a diffuse sound field called reverberation, which is captured back by the microphone as a tail which follows the direct sound.

The result is, then, far from the professional ideal of a vocal booth in a recording studio, a space conceived as a laboratory environment with dry acoustics (with no noticeable reverberation) designed for this purpose.

How to reduce acoustic reverberation in a home studio?

The worst scenario is a big, void room, with nude walls. To improve its response, sound rays must impact absorbent materials that will stop the reflections (they transfer the energy to heat, in a negligible amount). The materials professionally used are:

  • polyurethane foam, cut in pattern shapes in the form of pyramyds, waves, peaks… and can be attached to the walls using adhesive, and
  • mineral fiber panels covered by fabric, that you can hang at the walls as a picture.

The strategy is to cover a certain percentage of the surfaces. We can begin from the spots at the same height and position of the microphone in all directions (front wall, rear wall, and lateral), called “first reflection” points, and, if we have more absorbent material available, continue distributing it regularly. The absorption effects are accumulative (the more the treated surface, the weaker the acoustic reverberation).

Reverberation in room

In a home environment, porous textile materials of a certain thickness present also absorbent properties, so matresses, pillows, carpets, thick curtains, upholstered chairs… also perform the same function.
A book shelf also shows some absorption properties, and diffusive as well (another desireable acoustic property, that indirectly also reduces reverberation).
So all the elements that can obstruct and disperse sound (chairs, tables, objects in general) will be welcome too.

In particular, a carpet is highly recommended. Since it stops the multiple reflections of the floor-ceiling parallel surfaces, and for the purpose of this text dedicated to home environments, treating the ceiling would be more difficult or less aesthetic.

Commercial solutions that substitute the acoustic treatment of the room

  • A modular acoustic booth (from brands such as Studiobricks or Demvox) would be the highest-end option discussed here, at a price starting from 3.500€. It’s a complete room by itself, with all the necessary. The advantages are: it has certain isolation properties (soundproofing), and includes the basic acoustic absorption by default. As a disadvantage, the smallest dimensions booths produce a resonant sound at low-mid frequencies (boxy sound). But they solve perfectly the major issues of an untreated room, and are a common and recommended option for professional voiceover talents.
Demvox recording booth
  • An Isovox “portable booth”. The developer of this idea is this Swedish brand, and consists of a semi-closed setup that will surround just the microphone and the head of the voiceover talent. Absorption is fantastic, although there are some inconvenients: it can be uncomfortable (specially in the full setup that uses the back panel, as it can become really hot inside) and its price, around 900€.
Isovox acoustic booth

Partial commercial solutions

  • An absorptive enclosing for the microphone: the Kaotika Eyeball product (around 200€) is an absorptive sphere made of foam that covers the microphone, with one only opening for its front direction. This has inspired other, more cost-effective solutions, such as Alctron PF8 or Nowsonic Isolator (around 50€). These are very good options for a home studio offering a great performance for the price, although they are not perfect: they alter the properties of the captured sound, and some acoustic treatment of the room is still needed, because part of the reverberant sound is still picked up. But, for a minimum investment, the improvement is relevant.
Alctron PF8 Pro acoustic filter
  • An acoustic screen (or reflection filter). It absorbs the microphone’s rear area and to some degree the lateral sides, but it doesn’t enclose the microphone completely, leaving the superior and inferior areas free. It won’t save us from the need of treating the room, but rather it’s conceived as a complement.
Acoustic filter

DIY ideas

Understanding the basic concepts, some voiceover talents and singers employ alternate homemade ideas. For example, an open booth where matresses stacked vertically will behave as absorbent walls.

Recording booth with matresses
Photo by Michael Garate, CC3 license

Or the closet solution: a clothes wardrobe will become a partial vocal booth where we will place the microphone. Acoustic foam can be attached (or a blanket hung at the bar) as posterior absorbent, and if we put more foam or simply hang clothes at both sides, we will also have absorption in the lateral directions. If the room is not too reverberant, this solution can bring good results. Not comparable with a professional studio, but way superior to the worst extreme, as we said, of a big, void room, with nude walls.

Recording booth in a closet

Additional tips

  • The choice of the room for the home studio can be based, if possible, on the following parameters: less external noise, best possibilities for acoustic treatment, and, if there’s still a choice, avoiding a room that is too small. A good Internet connection is also important – better via a network cable, for reliable remote connections.
  • The most directional microphones pick up a bit less of room sound as they reject more sound coming indirectly. So an hypercardioid pattern (or 8-figure with the rear area absorbed) are ideas to consider if the room is very problematic.
  • Maybe you are wondering if a plug-in can elliminate acoustic reverberation once recorded. Although the quick answer until recently was a big “no”, there’s this tool called Izotope DeReverb. It can help a little in some cases, specially if the voice must be mixed with music. But it’s best to send the audio unprocessed, and leave this kind of tasks to the studio audio engineer!

If, as it seems, remote working will keep on going in the period ahead, collaboration between studios and voiceover talents will be more fundamental than ever. Here lies the intention of this article, that I hope it can be useful.
If you wish to hear good quality voice recordings, you can look around the studio Voice Bank.
And, if you can you work from your home studio, and your equipment and acoustics are good, then you can contact to be added to the studio database.

© 2020, Héctor Xiqués Escorihuela
IT Engineer Bachelor degree, speciality Sound and Image