The cost of top-quality audio recording gear is falling fast, making professional recording accessible in just about any kind of space. But the one remaining factor in “out of studio” recording is room acoustics. The sound in a space can make a major difference in the quality of your audio.
Whether you are doing remote recordings from an untreated room at a sporting event, podcasting from office space or even working alone in a home studio, acoustics matter. In fact, they may be the most critical part of the recording set-up.
Recordings tainted by a harsh or ugly-sounding room are doomed before they even begin. It’s almost impossible to make them sound good using even the best gear. Reverb, an online dealer of new and vintage pro audio gear, said that even more is at stake when mixing and mastering. A bad-sounding listening environment can seriously hurt the sound of any recording.
While no plugin, pedal or processor can change the laws of physics, there are a wealth of acoustical treatment products on the market from brands like Auralex, Primacoustic, GIK Acoustics, Audiomute and RealTraps designed to improve the sound of any room.
Pretty much any space can benefit from some type of acoustic treatment, but what kind that’s needed (and how much) can vary greatly depending on the space and what is being recorded.
Unfortunately, there is a lot of misinformation about acoustic treatment, and many people don’t educate themselves on how to use it effectively, Reverb noted. The pro audio company offered some advice on how to treat a non-studio space.
The kind of recording determines the treatment methods needed. For example, if all you do is record your own voice-overs, you might be able to get away with just a simple vocal shield, like sElectronics Reflexion Filters, to keep unwanted reflections out of the microphone. In most situations, however, it’s definitely worth investing a little time, money and effort into creating a good-sounding room.
If you record music with soft acoustic instruments, a “dead” sound without much reflection may be sought to achieve a focused sound. If you’re a drummer, you may want a tight, dead sound or a bright and lively sound depending on the style of music being played. If you record instruments with a lot of low-end content, like bass guitar or piano, it is good to minimize muddiness in the room. And when recording an entire band at once — depending on your taste — each instrument may be isolated as much as possible to avoid bleed in the other instruments’ microphones. Other sessions desire that bleed. Different strokes for different folks.
Mixing and mastering are critical-listening tasks, requiring carefully tuned acoustics for an accurate sound that will result in balanced mixes or masters. If what you’re hearing when you mix or master isn’t accurate, you’ll unconsciously compensate for it by adding or subtracting certain frequencies. Your recording may sound perfect in your room, but terrible everywhere else. If you mix or master in a make-shift studio, you’ll want to achieve as flat a sound as possible.
Absorption is a simple concept. It absorbs sound waves to stop them from bouncing around. Any soft material, like foam or cloth, will absorb sound by trapping and dissipating acoustic energy. In fact, your room probably already has some absorption in the form of couches, rugs or wall hangings.
Acoustic absorbers are widely available commercially, and prices directly correlate to effectiveness. Simple foam squares are a popular inexpensive option, but only attenuate high frequencies. Higher-end absorption panels are made of rigid fiberglass and can be effective at much lower frequencies, depending on their thickness.
Diffusion is the opposite of absorption. Instead of stopping sound waves, diffusers scatter them in different directions, encouraging a more random reverberation. Diffusers can range from simple, uneven surfaces to mathematically precise contraptions.
On the basic end, gently curved panels scatter sound in an even, radial pattern. More sophisticated products use mathematical algorithms to achieve maximum diffusion. One example is a Quadratic Residue Diffuser, which consists of “wells” of different depths targeted to specific frequencies. A skyline diffuser is a similar device made from square blocks arranged in a grid pattern that looks like a city skyline viewed from above.
Bass traps reduce resonances in the lower end of the spectrum, and are often large and bulky because of the mass required to control low frequencies. Bass traps come in two main varieties: broadband and tuned. Broadband bass traps are simply thick absorbers that attenuate a wide range of frequencies (directly related to thickness).
Tuned bass traps target one specific frequency by resonating at a certain pitch and converting acoustical energy into mechanical energy. They are usually cylindrical, with a column of air inside that determines their effective frequency.
Treating a room, Reverb notes, isn’t as simple as hanging panels and placing bass traps wherever they fit. In general, a too-reverberant room will require absorption, a room with flutter echoes will benefit from diffusion and a room with uneven bass response will need bass traps. To achieve the best possible sound in a make-shift studio, you have to know how to use each type of treatment effectively to achieve the desired results.
Absorbers can be spaced out across walls for general sound-deadening, but they can also be used strategically to eliminate reflections in one particular spot. This is known as a “reflection-free zone,” (RFZ) and it’s commonly used in recording studios to create a clear-sounding “sweet spot” in front of the monitors.
An easy way to create an RFZ is to sit in the monitoring position while someone runs a mirror along the walls, and place an absorber anywhere you see a speaker cone in the mirror. Some studios even hang a “cloud” above the monitoring position to control ceiling reflections.
If you like a live sounding room, diffusion is your best friend. A few well-placed diffusers can help achieve a more flattering reverb sound in a room, without deadening the sound at all. Diffusers are also useful when placed on the wall behind the monitoring position, to eliminate direct reflections from the speakers.
Pretty much any room can benefit from bass trapping, since every room has low-frequency anomalies that can result in a muddy, uneven sound. Since lower frequencies are much less directional than high frequencies, precise positioning isn’t critical for bass traps.
Bass does tend to build up in corners, however, making them out-of-the way spots for bass traps. Broadband bass traps are an all-purpose solution for uneven-sounding rooms, but if your space sounds good overall you may just need one or two tuned traps to target problem areas.
Most rooms need a combination of absorption, diffusion and bass trapping to sound their best. The key thing to remember is that every space is different, and every situation will call for a unique approach to acoustic treatment.
Once the goals are defined for a recording space, identify the specific problems in the room. Then educate yourself on how to solve those problems with acoustic treatment. If this is too complex for you, hire an expert to treat the room. The difference in sound quality will be dramatic.
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