Taking Audio in Another Direction.

Binaural Barricade Against The Audio Police

by John Sunier

Being heavily into headphones, I couldn’t resist having my curiosity aroused by Tom Corbin’s first column [in a past issue] announcing that he will suggest circumstances under which one may want to wear two pairs of headphones simultaneously. Well, I can’t imagine what circumstances those may be and am waiting with bated breath to find out, but in the meantime I can tell you about some circumstances you probably had not thought about in which you might want at least to wear one pair of headphones.

Tom’s “Audio Police” business also caught my eye and I couldn’t agree more. I’ve railed against some of the Audio Police dogma for years, such as the “hair shirt” approach to component features, especially dispensing with headphone jacks (since I’m into headphones) in preamps, not to mention tone controls. I’m going to do a bit of creative, lateral thinking such as Tom was encouraging, and among other things I’ll also give you a rock-solid reason why you should buy a graphic equalizer.

Room Treatment & the Sweet Spot

Rumors are that one of the leading very high end speaker exhibitors at Hi-Fi ’97 bragged about how great his speakers sounded without any acoustical treatment in the small and sonically-deprived room of the San Francisco hotel where it took place. Yet a little snooping after the demo revealed Tube Traps in the front corners and a bunch at the rear wall.

While both the Audio Police and those of us who prefer to think and hear for ourselves stress the importance of the listening room in the high end equation, it is the former, not the latter, who have escalated the ritual of room treatment to new complexities and expense. Many audio buffs buy more room treatment materials than they need, or entirely the wrong ones, because they don’t sit and listen while trying simpler, less ugly and cheaper means such as rugs, drapes, furniture, or CD/LP storage shelves.

Another problem connected to the room treatment emphasis is the narrow sweet spot encountered with many of the larger and most expensive tower and panel speaker systems. Loss of 50% of the sonic achievement of a typical large high end speaker when standing up from a seated position is not at all an unexpected occurrence. Even moving from side to side a few inches destroys most of the superior imaging and soundstaging of many two-speaker setups. How many of us can sit next to a friend or spouse and be assured that the other person is hearing exactly what we are hearing in our carefully-aligned sweet spot? OK, so the majority of the audio unwashed out there has never heard of the idea of sitting equidistant from the two speakers in an equilateral triangle and thus has one speaker horizontal at floor level in one corner with the other vertical high up on another wall. The Audio Police have gone too far the other way – resulting in some of the listening room diagrams appearing in some audio pubs looking like a prison cell with a kitchen chair two-thirds of the way back, two speakers one-third of the way into the room, one little equipment cabinet to one side, and nothing else.

And in these ruminations on the sweet spot I’m not even addressing those approaches that REALLY have a narrow sweet spot – namely processes attempting to cancel some or all of the left speaker signal from reaching your right ear and the right speaker signal from reaching your left ear. (There used to be a specific name for this but it is now trademarked so I can’t use it). Among these are Carver Sonic Holography, Polk SRDS speakers, Lexicon Panorama circuit, and many new computer-related speaker-processing approaches that attempt to give a “3D” feeling to stereo sources heard through them.

In the computer area, I’ve never understood why all the research and effort are being expended to getting a 3D effect with dinky little speakers (and often a third little box laughably referred to as a “subwoofer”) when the computer user isn’t going anywhere and doesn’t require any freedom of movement. This is a perfect situation for headphones! Even inexpensive models can achieve better sound than the undersize speakers being sold for multimedia use; but better than that, headphones plus Binaural sound can precisely locate sounds anywhere in a full 360-degree sphere around the listener.

Everything You’re Listening To Is Wrong!

More than 200 million headphones were sold over the past decade, yet everything that nearly everyone is listening to on headphones was never designed nor intended for headphone playback – it was designed for loudspeaker playback! Stereo purposely mixes some of the left channel signal into the right and vice versa, and then when your pair of speakers are speaking in your listening room they do the same thing.

The result on headphones is what’s sometimes referred to as the “musical hat” effect – all the sounds happen inside your skull. Not only that, but half of the musicians seem to be clustered over just inside your left ear and the other half of them over just inside your right ear. Some people also hear another cluster in the middle of their cranium. The HeadRoom circuit offered by that headphone-oriented mail order service tries to connect these clusters via cross-feeding of the two signals to more closely emulate the effects of loudspeaker listening when wearing headphones. For many listeners and some types of music this subtle circuit enhances the listening to stereo material.

Biophonic Response Chart
[Vertical Scale = relative level in dB; Horizontal Scale= frequency.
Ron Cole feels this EQ can make listening to standard stereo sources on headphones
less bizarre-sounding to most persons, though not equalling true binaural.]

Here is a less subtle enhancement for listening to all these recordings and broadcasts that were never designed for headphones. Binaural recordist Ron Cole came up with this chart which corrects for ear canal resonance and other differences in the spectrum between speaker listening and headphone listening. It can be set up on a parametric equalizer or almost any multiband equalizer (those accessories which the Audio Police tell us should never have been invented). You don’t have to hit the various boost points right on the button — even getting close makes an amazingly more natural headphone listening experience when using stereo source material. While I have yet to try this in combination with the HeadRoom circuit, the two should be a synergistic duo. Remember though that neither of these band-air approaches locate the music outside of one’s head nor do they impart a “you-are-there” feeling in listening on headphones.

The Binaural Rap

There’s only one way to do that. That’s using true binaural recordings and any headphones. [Editor: Auralization processors will also image outside the head.] Here again we are at odds with the Audio Police, since absolutely no additional components are needed. Plus the ultimate in fidelity is not required to experience binaural recordings. The very first public experiments with it, in fact, took place at the Paris Opera in 1881, using primitive carbon transducers both on the stage and a pair of them hooked to two separate telephone lines at each subscriber’s home.

Even with a $25 walkman-type cassette portable and the ear-buds that came with it, one can have a jaw-dropping sonic experience with a good binaural cassette. One that I frequently suggest to binaural virgins is Stephen King’s “The Mist,” available at the Simon & Schuster audio book rack of most chain bookstores for about $9. It’s more hair-raising than any King movie. With a cast of about 30, original sound effects and music, you’re part of the horror drama. Monsters creep up on you from behind and drop down from the ceiling on you.

But it is with music that binaural can almost literally Take You Away. Isn’t the primary purpose of high end audio to Get Into the Music More? (The Audio Police may say that but their actions often contradict that.) Well, with binaural one is in the same venue where the musicians originally performed. One is aware of the room size and shape, and all the reflections that are such a major part of the musical experience are preserved instead of being turned into a general mish-mash of reverberation without any directional information, as with stereo.

The basics of binaural couldn’t be simpler, but recent improvements have brought it to such a level of viability and functionality that if recording engineers would only wake up to it they would be recording everything binaurally. It is now completely compatible for mono or stereo speakers as well as matrix surround sound playback.1 The heart of binaural is a dummy or artificial head which replicates the human head. The most vital features on it are the two outer ears or pinnae. They are usually formed out of soft rubber or plastic and often cast from actual human ears. Ridges and valleys in the pinnae reflect the sounds differently into the inner ears and therefore they are vital to recreating precise localization of sounds. The current interest in spherical mike systems for stereo preserves many elements that are part of binaural reproduction, but without the pinnae to reflect the incoming sounds to the omni mike capsules, the localization cannot be very specific.

The two channels from the dummy head must be kept absolutely separated all the way in the chain to the two drivers of the listener’s headphones. And the left mike on the dummy head must feed the left driver of the headphones and vice versa; the backs of our heads lack the features of the front and reversing the channels gives a confusing sonic image much as does reversing the left and right-eye images of a stereo photograph.

While even a $3.98 pair of ear buds will deliver good binaural, the better quality your headphones, the better will be your experience. We already know that it’s possible to get better sound with some of the high end phones2 than one could get with many of the most expensive speaker systems. Add binaural to that equation and you have a really amazing sonic experience. Add one of the many dedicated headphone amps now being produced3 and you’ll be hearing the ultimate. Add a longer cable and you’re no longer glued to that sweet spot! You can now take it with you, within reason.

Today’s Binaural

The Audio Police have decided that FM radio, audio cassettes and binaural are all not worth our consideration as far as high fidelity sources. I could expound at length on the idiocy of the first two, but that’s off the subject. Their beef with binaural is the claim that it sounds perfectly awful played back on loudspeakers. In the distant past that was somewhat correct; binaural recordings sounded a bit thin and distant. Part of this was the very poor bass end sensitivity of the consumer mikes, which were often built into headphones and had to have a low cutoff to avoid feedback! Even the recently-discontinued Sennheiser MKE 2002 binaural mikes lacked extended low end.

Today, however, the two commercial binaural mike systems used in 99% of existing binaural recordings are completely equalized for excellent speaker playback. After the first of the two gold binaural CDs from Newport Classics was released, a press event was held in the same auditorium in Pasadena where the recording was made. Speakers placed on the lip of the stage played back the binaural CD and all agreed it sounded as good or even better than the best standard stereo CD. 4 (Of course most of the “you-are-there” feeling is lost in speaker playback.)

The other binaural misconception is that there are no recordings available. Not true. They were extremely difficult to find, and when I began regular All Binaural Broadcasts on my local AUDIOPHILE AUDITION program about 17 years ago listeners reported that they asked in shops about binaural recordings but only got blank stares. So seven years ago I decided to start THE BINAURAL SOURCE, which is a web-based mail order business currently stocking over 125 different true binaural CDs and cassettes. Most of these are imported exclusively by us from Germany, France, Britain, Bulgaria, Japan, not to mention a growing number of small U.S. labels who lack distribution in the stores. The sounds cover classical, pipe organ, jazz, crossover, new age, pop, audio dramas (such as “The Mist”), nature sounds, and special sounds to enhance sleep and relaxation.

An extensive FAQ and more detailed information about binaural reproduction are found at THE BINAURAL SOURCE. Actual binaural demos for free downloading will be available there by the time you read this! A flyer describing 28 new binaural CDs and listing all 125+ recordings in the current catalog is available by calling 800-934-0442 (PST), emailing your street address to sunier@binaural.com or by writing to THE BINAURAL SOURCE, Box 1727, Ross, CA 94957.

Earnotes:

1 = I realize most LISTENER readers are staunch two-channel/two-speakerists, but if you buck the Audio Police by owning any sort of matrix surround sound processor (no DSP reconstructions, please), you will find that binaural CDs provide a superior surround soundfield to any Dolby Surround-encoded music CD.

2 = Among my personal favorites for binaural are the AKG K 1000, the Jecklin, Sony CD-3000 and any of the Grados.

3 = Headphone amps have been available from HeadRoom, McCormack, Audio Alchemy, AKG, Melos, EarMax, Creek. New headphone amps have been introduced by Musical Fidelity, Parasound, VLS, Sennheiser, Holmes·Powell, Moth Audio, Celeste, Pure Audio, Mesa Engineering, Naim and Bowman.

4 = Fellow audiowriter Martin De Wulf said this about the second Newport gold binaural CD in a recent Bound for Sound issue: “…while this recording does do some amazing, almost unbelievable things when listened to on a set of headphones, it sounds every bit as good when listened to through a pair of speakers.”

c. 1997, John Sunier.
From The Binaural Source. (Republished with permission.)

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Binaural In-Depth.

by John Sunier

So What Is Binaural?

The binaural experience places the listener sonically where the sounds on the recording or broadcast originated, and requires no special equipment of any sort other than the binaural source and a pair of stereo headphones. The listener experiences sounds quite accurately localized in a complete 360-degree sphere- a true virtual audio environment. It does this via two tiny omnidirectional mikes placed at the entrance of the ear canals on a replica of a human head (“dummy head”). The two signals are kept entirely separate all the way from this artificial head mike system to the corresponding left and right drivers of the headphones worn by listeners.Though all modern binaural recordings are perfectly compatible for loudspeaker playback, in a normal stereo speaker setup you will lose the “you are there” binaural effect due to leakage of the sound cues intended for one ear into the other ear and vice versa.

Even sophisticated audiophiles are often confused about binaural due to the wrongful use of the term back in the l950’s by many who used Binaural and Stereo as synonyms for one another. Recording pioneer Emory Cook (if you were around then you’ll remember his twin-tracked early stereo LPs) was one of these. Yet in the notes provided with all RCA Victor two-track stereo open-reel tapes starting around 1956 was the following:

Stereophonic recording differs from Binaural (a term sometimes incorrectly applied to stereophonic records) in that the microphone placements are selected for loudspeaker reproduction. Binaural properly applies to a two-channel system designed for headphone reproduction. It thus requires the use of two channels fed by microphones spaced about seven inches apart (normal ear separation).

That definition just about tells the tale. All of us have noticed the tremendous difference between hearing a stereo recording on speakers and hearing it on headphones. Headphones seem to put a giant sonic magnifying glass on all aspects of the recording, including stereo separation. Many recordings sound like half the band or orchestra is in one studio with its signal feeding your left ear, and the other half in another studio with its signal feeding your right ear. The sounds seems to be localized at your two ears and totally inside your skull rather than happening outside your head. Some persons also image a central area of sounds in their skull, so that it feels like three little separated groups of musicians inside your head. The HeadRoom circuit was developed to minimize this effect when listening to standard stereo recordings.

The truth is that over 200 million stereo headphones having been sold in the past decade (way over 600 million if you include all the throw-away headphones bought by those airlines no longer giving passengers primitive plastic tubing). But the source material that nearly everyone is listening to on their headphones was never designed for listening on headphones, but for playing via loudspeakers! With speaker playback, the left channel sounds are meant to reach the right ear and visa versa. Producers of commercial recordings almost always monitor with speakers rather than headphones. Binaural keeps the left and right channels absolutely separated from the original dummy head (or your actual head) all the way to the listener’s headphones without mixing. This applies whether the medium is a recording, live, or a radio broadcast.

Professional Mike Systems For Binaural

Commercial binaural recordings generally use one of two different expensive professional “dummy heads” (“Kunstkopf” in German). In fact, both come from Germany. The Neumann KU-81 or KU-100 head was probably used — often in conjunction with other mikes — on a CD or two in your collection. (Cost: about $6500.) The Aachen Head Acoustics system is more complex, with special equalization to achieve the most natural reproduction on both speakers and headphones. (Their current model is also used for precise acoustic measurement and runs about $29,000.) Some recording engineers feel either of these mikes is capable of making more natural and well-balanced ordinary stereo recordings for speaker playback than the best purist mike techniques. Of course, the full binaural effect is not present in speaker playback except with expensive specialized cross-cancellation electronics; which also force you to sit in a narrow “sweet spot” without the freedom of movement that headphones allow. However, any matrix surround processor using “ambience recovery” rather than “ambience synthesis” will give a better surround sound effect with binaural recordings than with most specially-encoded Dolby Surround CDs. Most Dolby Pro Logic decoders will suffice, though processes such as Circle Surround, Six Axes and EARS are even better. Just stay away from what colleague Dan Kumin calls “boingerizers” – those Hall/Stadium/Jazz Club processors that artificially generate reverberation (echo) to add to the original ambient signal on the recording.

A visible dropping of the jaw is the most frequent indication that someone who has put on headphones is hearing effective binaural for the very first time. Followed by exclamations of surprise, wonder and unbelievability. Binaural, rather than trying to bring the sounds into your listening room, takes you where the sounds originally occurred. You are aware of sounds 360 degrees around you ­ not just right & left but forward & back and up & down! Someone whispering in one ear can make you jump, and a good rainstorm in binaural will have you opening your eyes (if they’re shut – which helps the impression) to make certain you’re not actually getting soaked!

In Binaural, the pinna or outer ears of the dummy head or head of the original recordist set up subtle interference patterns that locate the sounds around the head quite specifically in space. These are known technically as HRTFs – Head Related Transfer Functions – and have become central to current audio research directed toward achieving virtual audio effects with two or more loudspeakers that approach the realism of binaural with headphones. Computer gaming and virtual reality software are fertile fields for this sort of enveloping sound. Sounds coming from directly in front of us bounce off the rear part of the outer ear; sounds from below bounce off the top part of the ear. When a sound is directly in line with the left or right ear there is a straight shot into the ear canal, and this provides different directional information from the other approaches. The ear/brain combination works together closely in binaural hearing. Take for example “the cocktail party effect” – in which we “steer” our binaural hearing around a noisy room and focus it on the one person we want to hear, while minimizing the distraction of other voices.

Early Binaural

The first experiment with binaural, way back in 1881, compared the effect to the popular stereoscopic views of the period. The inventor said of his binaural patent, “This double listening to sound produces the same effects on the ear that the stereoscope produces on the eye.” He set up a series of carbon telephone mikes in pairs (about 7 inches apart) along the edge of the stage of the Paris Opera. As the singers performed on stage, their voices were carried on twin pairs of telephone lines to a few subscribers homes who had two lines installed. They put the earpiece from one line to their left ear and the earpiece from the other to their right ear. Fortunately, a wide frequency response is not a requirement to convey the binaural effect, because the phone system of the time was surely quite primitive.

More Recent Binaural Activity

There has been sporadic interest and activity in binaural since those early days late in the 19th century. In the middle 1920’s some radio stations in Connecticut and elsewhere broadcast experimentally on two different frequencies — feeding each transmitter separately from a left-ear and right-ear mike in a dummy head in the studio. Listeners were already listening on headsets for the most part, since primitive speakers were just coming into fashion. So this worked out well — they merely put one mono headset, tuned to the left-ear station, to one ear and put the other mono headset tuned to the second station, to their right ear. Some of the West German radio stations have devoted time to special binaural transmissions — often of radio dramas which they call “horspiel.” There has also been interest in Japan. “The Cabinet of Dr. Fritz” series of binaural radio dramas from ZBS Productions was carried for some years on public radio stations here in the U.S. Many of those same stations also carried my own weekly program, AUDIOPHILE AUDITION, on which I presented All Binaural Special broadcasts once per quarter for over 13 years.

In 1970 Stereo Review offered a binaural demonstration LP of music and sound effects which used a homemade dummy head known as the Blue Max. There have been many binaural recordings available in Germany, mainly of classical material and on LP. The disadvantage of employing either analog LP or cassette for binaural material is the noise problem. The surface noise or hiss that we have become accustomed to when listening via loudspeakers can become intolerable with headphones. The greater clarity via headphones makes extraneous noises in the source stand out and detracts from the total sonic experience of binaural. Add to that a peaky high end in some headphones that further points up surface noise and hiss compared to speaker reproduction.

As a result of this, the compact disc and other digital media such as MiniDisc and DAT have proven the perfect medium for binaural. The excellent signal-to-noise lets the listener concentrate on the sounds and begin to forget that he or she is actually listening to a recording – one just starts to take part in the original music or sound-making!

You Can Do It Yourself

Their introduction to binaural makes a great impact on some listeners. Then when they learn how basically simple the recording process can be they are energized to make their very own binaural recordings. Some years ago consumer-level binaural mike systems were offered by Sennheiser, Sony and JVC, but have been long discontinued. Today several suppliers provide a variety of in-ear mike systems at a $70-$300 price range. They are usually paired with a DAT or MiniDisc portable recorder, though a good quality cassette recorder may also be used. [Editor: See the Commercial Links page for binaural resources.]

For such recording efforts, sounds in motion are especially effective in binaural, as well as sounds that are spatially separated. I have some binaural tapes of a symphony orchestral rehearsal, and for demo purposes, it must be admitted that feeling like you are sitting right on stage with the orchestra during the rehearsal, with music stands clanking, chairs squeaking, the conductor walking around to help some of the players with small problems, can sometimes be more exciting than hearing the final performance of the music. Sound effects such as a motorcycle or train passing by, take on a quantum step in “you are there” realism with binaural vs. the old-fashioned stereo demos of trains passing between your loudspeakers. Keep some of these tricks in mind when doing your own recording with binaural mike systems. For example, if you have a quartet of instruments or singers, have them perform in a circle around you instead of in a line in front of you! (I’m a nut on sax quartets and do they ever sound great recorded in this way!) Instead of sitting out in the front row of the audience to tape an early music ensemble, one recordist set up his dummy head with mics in a chair right in the middle of the group onstage – creating an effect as though the listener is one of the musicians performing! – most exciting early music recording I’ve every heard. The surrounding spatiality adds great interest to the music. Another recordist taped his taking an elevator, walking into the concert hall and settling in his seat at the beginning of a concert and then the reverse at the end to make it a more complete binaural experience for listeners. (Unfortunately, the elevator was totally silent, so he edited out that part.)

Headphones For Binaural

While binaural can be heard with any stereo headphones down to the simplest $5 “ear-buds,” the better the phones, the more amazing the experience. I have found some of the Sony phones around the $100 price point to be good. (The Grado SR-80 at the same price is excellent.) I can’t vouch for current Sony models, but do stay away from the MDR-V6 (once recommended by Consumer Reports) because it destroys much of the binaural effect. Among the best under-$600 phones I have heard for binaural are the Sennheiser HD 600, SONY MDR-CD3000, AKG K-501, Beyer 990 Pro, Etymotic ER-4S, and Grado RS-1. (No special order intended in that list.) The K-500 has many of the qualities of AKG’s flagship K-1000 ($895) which I find the best all-around binaural phone due especially to its ability to help image the sounds outside one’s head. The Jecklin and Ergo headphones from Switzerland, at about the same price point, also offer this advantage. The Etymotic are basically test probes inserted deeply into the ear canals – just the opposite of the off-ear-driver phones. However, their fans rave about them for binaural, and with the tight seal to the eardrum bass reproduction equals the most monster subwoofer you could fit in a room! Extra-cost custom ear molds make the Etymotic more comfortable for extended wear.

The Grado RS-1 Reference phones and the Sennheiser HD 600 are also excellent and of interest to those who find the AKGs too bizarre with their little earspeakers suspended on either side of your head. Both the Grado and Sennheiser provide more deep bass than any other on or off -ear headphones I have heard. The Stax electrostatic earspeakers have been the standard for binaural for years. Their top-of-line Omega has a dedicated tubed amp and goes for over $4000 but is probably the best-sounding headphone ever. Don’t worry about the suitability to binaural of feature differences such as circumaural vs. on-ear, free field vs. diffuse field or electrostatic vs. dynamic. Even extended frequency response is not a prerequisite for successfully transmitting the full binaural effect. Phase accuracy and flat response within the frequency spectrum are the most important parameters. A trend showing the increased interest in headphones and binaural is dedicated high end headphone amps — HeadRoom, Melos, Grado, Music Hall, Musical Fidelity and others have them. AKG will introduce a new model soon. Some of the high end phones practically demand a good dedicated amp, and even a modest amp can upgrade the sonics of a more modest headphone.

c. 1999, John Sunier.
From The Binaural Source. (Republished with permission.)