isolation headphones

Isolation headphones and your home recording

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Extreme Isolation headphones can be a game changer for your home studio recording, remote location recording, and audio mixing

The home recording revolution brought affordability and access to millions of musicians. But with this sea change, a problem crept into the bedroom and living room of many a musician’s home studio. Performing and recording in the same space affects what we hear and how we perceive the sound of the performance. Simply put, if you are recording drums or electric guitar in the same room as your home studio recording rig, you likely can’t hear what you’re recording with enough isolation from the original sound source to make critical judgment calls.

Sure, throwing a packing blanket over the amp, or building isolation panels to put around the drums will help, but there’s still going to be some leakage. What’s a recording musician to do short of building an expensive additional iso room to track instruments in? It may be as simple as purchasing a new set of headphones.

US-made Direct Sound Extreme Isolation headphones can be a game changer for home recording studio owners. For about the price of a good dynamic mic, the use of extreme isolation headphones can have a major impact on the accuracy of what you hear and record in your home recording studio environment.

Why sound isolation matters

In nearly every aspect of audio or recording, isolation is a key. Whether as a front-of-house live performance mixer, a remote broadcast/recording engineer working in a church or club, a recording engineer working on a studio session, or simply recording instruments in your modest one-room home recording studio, being isolated from your audio sound source is essential to producing a quality finished product. In order to make the best decisions about levels, EQs, dynamics, or effects, it’s necessary to hear the uncolored sound on its own. Thus, some level of sound isolation from the actual sound source is crucial.

To remedy the sound isolation issue, a recording engineer will often turn to headphones. Although headphones resolve many of the isolation problems that arise in most environments, not all headphones provide the level of sound isolation needed to accomplish these tasks optimally. We tested the Extreme Isolation headphones model EX-29/-25 to see how they differ from the standard variety of stereo headphones and how to get the most out of the isolation headphones you purchased.

EX-29 isolation headphones
Extreme Isolation EX-29 headphones

What makes a pair of isolation headphones?

What makes isolation headphones different? To begin with, once placed on your head, a good pair of isolation headphones does just what the name suggests: they isolate you from the surrounding audio environment. Measured by the amount of external noise reduction in dB or “passive attenuation,” isolation headphones are measured by using a frequency reference level in Hz, producing a Noise Reduction Rating (NRR) in Decibels (dB).

The EX-29 Extreme Isolation headphones have a passive attenuation level of -36.7dB at 8000Hz, resulting in a NRR of -29dB. The greater the NRR, the more efficient the isolation. For many of us, these numbers may not have much meaning. So, here’s a simple experiment you can try with any pair of isolation headphones.

Take a pair of headphones and connect them to your favorite music device. Pick a track, set the volume to a moderate listening level, hold the phones in front of you – don’t put them on – and note how loud the music is. Then press the two headphone cups together and note the amount of audio level reduction. Can you still hear the music? Is the volume greatly reduced, or just moderately? That’s a quick way to get an idea of what the NRR is trying to measure: how much unwanted sound is being kept out of your ears via the isolation headphones.

The EX-29 and -25 both feature a closed-back headphone cup design and have excellent overall frequency response. Unlike the familiar “noise cancelling” headphones favored by frequent flyers, the Extreme Isolation line of headphones does not use any active frequency or phase cancellation and require no batteries, hence the term “passive attenuation.”

Headphones vs. the room

EX-25 isolation headphones
Extreme Isolation EX-25 headphones
There are many types and styles of stereo headphones, ranging from low end $9.99 ear buds and consumer models to high-end professional studio headphones costing $500 a pair. Some headphones are closed-back to separate the user from the immediate studio environment while others may feature an opened or semi-opened back, allowing varying amounts of room sound to be heard along with the audio being reproduced in the headphones. In all cases, the primary usage for headphones is to listen to audio playback from a “close” stereo perspective.

Commonly, we listen to music in a “room” such as a living room, kitchen, or your car’s interior. Room sound comes at us as a stereo left and right signal, or from multiple points when using a 5.1-channel surround system. In any case, there is a moderate distance between the audio source, generally a loudspeaker, and you. Because the audio level in the room can be easily adjusted, sounds outside the room may (or may not) have little relevance to the listening experience. In the car, that changes slightly because of road and car noises. However, radio stations, for the most part, optimize their signal to maintain a consistent dynamic range. The overall volume coming from your car stereo signal remains pretty consistent even if a quiet musical passage occurs. In addition, new car interiors are now designed with acoustics in mind, further isolating the passengers in the car from external road noises.

In the recording studio, sound gets put under a microscope where every tiny nuance can make a difference in the finished recording. Yes, we still listen to sound a specific distance from the audio monitors in both the control room and sound studio, but headphones are used as an important secondary audio monitoring system. In the control room, headphones can be used for making fine adjustments to the stereo mixed image, and in the sound studio, headphones are used while recording instrument and vocal overdubs. However, the headphones generally used for making stereo mixing decisions may differ in design and price point from those used when overdubbing a cello, screaming rock guitar, or double bass drum kit.

Recording studio applications for Extreme Isolation headphones

In the campus recording studio where Jeff teaches sound recording, the Extreme Isolation headphones come in handy for many purposes. (Full disclosure, he has owned a pair for about a year.) Because they isolate the listener from the room so well, they are used on a daily basis. The reverse, separating the room from the listener, works equally as well. To put this in perspective, here are a few examples from recent sessions.

When miking a five-piece drum set, Jeff pointed out that generally students use a total of six to ten mics on the kit. They select dynamic mics as close mics on the kick, snare and tom surfaces, and condenser mics as overheads. They may also set up room mics to create a larger sound in the subsequent mix.

Many times when printing the basic drum tracks the producer or drummer will request a click track as a tempo reference. The click needs to be heard in the headphones, louder than the level of the drums in the room. This often results in a printing of the audible click as leakage from the headphones bleeds into the mics around the drums. It’s especially noticeable on the quiet passages, song count downs and any extended passages where the drums lay out of an arrangement. Getting rid of that leakage is one more tedious job before mixing and often changes the sound color of the overall mix if the overheads or room mics are muted.

When students gave the Extreme Isolation headphones to the drummer, the click was loud enough in his headphones but was totally removed from what the mics on the drums were picking up. Problem solved!

A similar scenario occurs when tracking a singer/songwriter who plays an acoustic guitar with vocals. Once again, the reference click bleeds through the mics as the soloist plays a soft strumming passage with no vocal. We swapped out her normal headphones with the EX-25s and all traces of the click in the printed track were gone.

Another use for the Extreme Isolation headphones is when experimenting with mic placement, something we do a lot in our recording classes. As the instrumentalist sets up his or her instrument, the student engineer puts on the isolation headphones on and listens to the sound of the instrument from the perspective of the microphone being tested or placed. She then moves the mic around to hear the differences that mic placement has on the sound that will go to the DAW. In her headphones, the surrounding room is almost totally eliminated so the student engineer can hear precisely where the best location or sweet spot is to place the microphone. This works especially well on individual drums, acoustic instruments and even guitar amps.

Live recording at the Take 5 Jazz Club

We had a remote recording date, so we brought a pair of EX-25 isolation headphones to the club for more testing. The students’ remote recording assignment was to capture a two-set live performance of the Jim Snidero Jazz Quartet. The remote was to take place at the Take 5 Jazz Club, a medium sized lounge and dining room, roughly 50’ by 50’ with a bar across from a stage area in one corner.

There’s a small kitchen service area with a door that can serve as separation from the performance space, so we normally use that as an impromptu control room to have some degree of sound isolation. However, this time the service area was filled with kitchen supplies, so we had to set up directly in the room where the group would perform.

After setting up a table and placing our small mixing console (a Mackie 1402) and hard-disk recorder (an Alesis Master Link 9600), mics were placed on the kick drum, snare, upright bass, electric jazz guitar amp, and alto sax. Two small diaphragm condenser mics were placed as overheads to cover the entire stage.

Using isolation headphones at the Take 5 Jazz Club
Live recording setup at the Take 5 Jazz Club

The standard pair of headphones we use, Audio Technica ATH-M40s, would not block out enough of the ambient room sound from our desired headphone mix, as they are not designed for maximum sound isolation. So the mixer would be fighting with sound from patrons, bartenders, and the band’s own sound to hear what was actually being printed. Decent isolation is also very important when mixing low frequencies produced by either an upright bass or kick drum.

In addition, since we record live to two-channel stereo, understanding the relationship of the acoustics from the direct instrument mics with those of the room overheads is crucial for getting the right balance between room and the direct sound.

In this case, the Extreme Isolation headphones did the trick. From the outset, during the sound check, the EX-25 completely isolated the recording engineer from the room sound, allowing him to make precise audio adjustments to the stereo mix. Throughout the night, when the band took a break, we checked the balances and agreed that each instrument’s level and timbre sounded excellent, as did the balance between direct and room mics. At the end of the recording session, the entire remote production team agreed we couldn’t have produced the same results without the Extreme Isolation headphones.

With a street price of $129 for the flagship EX-29s, which offer slightly better frequency response and isolation specs than the smaller and lighter-weight EX-25s ($99), these headphones are affordable and are something you might want to consider adding to your recording kit. From live recording situations to any number of potentially noisy setups where sound isolation is desired, these headphones can help you hear what you are capturing to disk/tape with a level of isolation and clarity that can improve your results immediately.

Keith Hatschek is a regular contributor to Disc Makers Echoes blog and directs the Music Management Program at University of the Pacific. He’s also written two music industry books, How to Get a Job in the Music Industry and The Golden Moment: Recording Secrets from the Pros.

Jeff Crawford is a recording engineer and producer with more than 30 years industry experience. He also teaches music technology at Pacific.

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