Sound, Space & AMBEO

It’s 9.1, it’s bin­au­ral — just what ex­actly is Sennheiser’s AMBEO plat­form all about?

Sound + Image - - Test - Jez Ford

Sound and space be­come one”, an­nounced Dr An­dreas Sennheiser at the Global Press Con­fer­ence for IFA 2017 in Ber­lin. “If the brain can’t dif­fer­en­ti­ate be­tween re­al­ity and re­pro­duc­tion, we are there.”

He was talk­ing about AMBEO, Sennheiser’s “3D au­dio ex­pe­ri­ence on head­phones or loudspeakers”. The com­pany has been putting in­creas­ing em­pha­sis re­cently on AMBEO, but for what pur­pose, ex­actly? It’s clearly evolved since we first re­ported on it, when AMBEO was pre­sented as a vari­a­tion of mul­ti­chan­nel au­dio, more for mu­sic than movies, and re­played on a 9.1-chan­nel loudspeaker sys­tem. Sennheiser’s ‘ton­meis­ter’ and sound en­gi­neer Gre­gor Zielin­sky was pi­o­neer­ing such mu­sic record­ings in 9.1, and he spent sev­eral years demo­ing and ad­vo­cat­ing this record­ing tech­nique at ex­pert meet­ings and (pro) au­dio con­ven­tions, cul­mi­nat­ing with open demon­stra­tions at CES 2016 in Las Ve­gas, and else­where.

The 9.1-chan­nel AMBEO sys­tem in­cludes height el­e­va­tion speak­ers, and in ad­di­tion to the na­tive mu­sic record­ings the sys­tem could up­scale from two-chan­nel stereo. It found early ap­pli­ca­tion in event au­dio, in­stalled for a trav­el­ling David Bowie ex­hi­bi­tion in 2015 and cur­rently for the Pink Floyd ‘Their Mor­tal Re­mains’ ex­hi­bi­tion at Lon­don’s V+A Mu­seum, which in­cludes an AMBEO mix of Floyd’s ‘Live 8’ per­for­mance (a slightly awk­ward one-off re­union in 2005 be­tween Roger Waters and the rest of the band). This adds one more mul­ti­chan­nel for­mat to the

Floyd’s long ex­per­i­men­ta­tion through quadro­phonic ‘Dark Side’ to Hugo Zuc­carelli’s Holo­phon­ics tech­nol­ogy on ‘The Fi­nal Cut’ (slightly scan­dalous, see panel over­leaf).

But the do­mes­tic mar­ket for mul­ti­chan­nel au­dio is in no­to­ri­ous de­cline, and is heav­ily weighted to­wards movies, where Dolby At­mos, DTS:X and Auro-3D are al­ready defin­ing the new adap­tive and/or ob­ject-based de­liv­ery of sound­tracks, and oc­ca­sion­ally mu­sic. And by CES 2016 Sennheiser was al­ready shift­ing em­pha­sis to “a strate­gic fo­cus on 3D im­mer­sive au­dio”, see­ing the rise of vir­tual re­al­ity and 360 video as key mar­kets for a wider def­i­ni­tion of im­mer­sive au­dio. Th­ese ap­pli­ca­tions would seem to be the very an­tithe­sis of loudspeaker-based mul­ti­chan­nel re­pro­duc­tion, re­quir­ing two-chan­nel head­phone de­liv­ery of an im­mer­sive en­vi­ron­ment, able to track or match video move­ment. And when the AMBEO logo was un­veiled, it in­cluded the tagline ‘Cap­tur­ing - Mix­ing - Pro­cess­ing - Lis­ten­ing’, high­light­ing Sennheiser’s abil­ity to de­liver at ev­ery point of the chain thanks to its com­bi­na­tion of pro­fes­sional and con­sumer prod­uct lines — from mi­cro­phones through to head­phone de­liv­ery.

To­day, then, Sennheiser splits AMBEO into three ar­eas. “Pick your blue­print”, says its guide to AMBEO best prac­tise. There is AMBEO for loudspeakers, “record­ing 3D mu­sic for 9.1 loudspeaker set­ups and beyond”. Se­condly there is AMBEO for bin­au­ral, “for easy on-the-go head­phone re­pro­duc­tion”. And thirdly AMBEO for Vir­tual Re­al­ity, “fully im­mer­sive sound – Sennheiser’s take on Am­bison­ics”. Bin­au­ral ver­sus Am­bison­ics Bin­au­ral and Am­bison­ics are two quite dif­fer­ent things. Bin­au­ral record­ings are gen­er­ally made with mi­cro­phones placed in the ears of dummy heads to cap­ture ev­ery nu­ance of what our ears truly re­ceive, and are then re­played through head­phones or ear­phones with the hope that the re­sult con­vinces the brain that the sound is real and im­mer­sive. Soft­ware to­day can mix to bin­au­ral, and there is also a ‘quad bin­au­ral’ tech­nique which re­quires four sets of bin­au­ral dummy heads. There have been pe­ri­odic re­vivals of in­ter­est in bin­au­ral record­ing, and we are see­ing this at present — Episode 4 of the cur­rent Doc­tor Who sea­son was given a spe­cial bin­au­ral mix made avail­able on ABC iView — head to 23:30 for some highly ef­fec­tive knock-knock­ing ef­fects with clear ‘be­hind you’ di­rec­tion­al­ity, show­ing off the bin­au­ral abil­ity to de­liver con­vinc­ing po­si­tion­ing.

Bin­au­ral is, how­ever, a fixed two-chan­nel record­ing. Am­bison­ics aims for a chan­nel-in­de­pen­dent spher­i­cal sound field, which should be able to be adapted to any speaker lay­out — and, cru­cially for VR ap­pli­ca­tions, which al­lows for dy­nam­i­cally ma­nip­u­lated bin­au­ral play­back on head­phones. And although var­i­ous parts of the tech­nol­ogy were orig­i­nally patented and li­censed out of the UK (Nim­bus Records was a key li­censee), the main patents are now ex­pired, so that any com­pany can de­velop the ideas.

Last year Sennheiser brought its mi­cro­phone ex­per­tise into play to cre­ate the Sennheiser VR Mic, a beau­ti­ful ob­ject (pic­tured below left) with four iden­ti­cal con­denser cap­sules in a tetra­he­dral clus­ter — it’s like a 360 cam­era for au­dio. It records to four sep­a­rate chan­nels at once, ex­pand­ing the idea of an M-S mi­cro­phone where the pri­mary au­dio is recorded with a left-right sound­field for width; the VR Mic adds front-back and up-down to th­ese. For pro­fes­sional record­ings it would be likely to add sep­a­rate spot mi­cro­phones to high­light de­tails or for clean di­a­logue pick-up, and for aug­mented re­al­ity, as Dr An­dreas Sennheiser put it, “this is more than the real world — we need to blend it with the vir­tual world”.

The mix­down is, there­fore, not triv­ial, and to de­liver an ef­fec­tive twochan­nel re­sult for head­phones or VR gog­gles, bin­au­ral ren­der­ing soft­ware is re­quired, in­clud­ing Head-Re­lated Trans­fer Func­tion pro­cess­ing to de­liver the brain-con­vinc­ing el­e­ments that come from true bin­au­ral po­si­tion­ing. Yet de­spite the com­plex­i­ties, the in­ter­est is high — ac­cel­er­at­ing global in­vest­ment in VR and 360 video has seen Sennheiser sell more than 2000 of th­ese mi­cro­phones since its launch last Novem­ber.

Away with your dummy head Mr Neu­mann; Sennheiser’s AMBEO Smart Head­set means we can now use our own.” Neu­mann KU 100 dummy head, im­age: EJ Pos­sel

AMBEO Smart Head­set: a re­view The $3000+ VR mi­cro­phone is, how­ever, hardly a thing for the more ca­sual video maker or record­ing fan. Sennheiser’s lat­est de­liv­ery, how­ever, proves quite the mar­vel in that re­gard. We have been play­ing with a sam­ple of the AMBEO Smart Head­set, pre­sented to us at the IFA GPC by Dr An­dreas him­self, and we love the re­sults — though we might note that we had been less im­pressed with the short head­set demon­stra­tions be­ing given in the Sennheiser booth at CES 2017 back in Jan­uary.

The con­cept is sim­ple enough — ear­buds with mi­cro­phones on the out­side, able to record na­tive bin­au­ral two-chan­nel from as near as damn-it the bin­au­ral dummy head po­si­tion. Dr An­dreas noted the ex­pe­ri­ence of Sennheiser and sis­ter com­pany Neu­mann in this re­gard — the Sennheiser MKE 2002 “head stereo mi­cro­phone” in 1974 and Neu­mann’s KU 100 dummy head in 1992. The new AMBEO Smart Head­set brings the tech­nol­ogy firmly into the the 21st cen­tury — for starters it’s built for Ap­ple de­vices only, its cable ter­mi­nat­ing in an Ap­ple Light­ning con­nec­tor, and ap­par­ently only work­ing with OS 10.3.1 and above. The

two omni-di­rec­tional mi­cro­phones are cov­ered with un­ob­tru­sive sil­ver grilles on the ear­pieces which hook over your ears, de­scend­ing to a 7cm lozenge which con­tains “a pre­mium A/D con­verter, mic preamp and SoftLimit from Apogee” — Apogee gets a ‘pow­ered by Apogee’ credit on the back, and its re­ward seems to be that for au­dioonly record­ings, you’ll need to buy the Apogee Me­taRecorder app (pic­tured left; no great ask at $7.99; the free ver­sion will record only 60 sec­onds at a time).

But the Smart Head­set also records with­out need for fur­ther pur­chase to the iPhone’s own Cam­era app when video record­ing, and this de­liv­ers re­sults so spec­tac­u­larly su­pe­rior to the iPhone’s own mi­cro­phone that it takes only mo­ments to be con­vinced. The rich bin­au­ral sound­field avoids the usual ‘head­phone’ sound of a plane be­tween left, right and front/top of head — in­stead it is truly im­mer­sive. While the bulk of the sound does pan to hard left and right (the zones of max­i­mum sen­si­tiv­ity for the mi­cro­phones) there is enough sur­round­ing de­tail to fill a real at­mos­phere of be­liev­abil­ity.

There are new record­ing rules to be learned — don’t point the iPhone with­out also point­ing your head; most peo­ple nat­u­rally pan a phone mov­ing just their arm or hand, whereas to track sound ac­cu­rately with video, you need to pan with your whole body. And if, like us, you find ear­buds need con­stant lit­tle pushes to lodge them deep enough in your ear for full bass re­sponse, well, here you’ll be push­ing on the mi­cro­phones and so caus­ing big rustling noises.

An­other odd­ity (per­haps to be cor­rected later, as th­ese were an early sam­ple) — you don’t hear what you’re record­ing un­til you play it back; they don’t play au­dio through the buds while you record, leav­ing you in a strangely silent world, pas­sively iso­lated by the ear­buds. We thought this was pos­si­bly to avoid feed­back be­tween the ear­buds and the mikes, but with the Apogee app you can turn on ‘In­put mon­i­tor’ in set­tings to hear the sound live, and with­out ap­par­ent prob­lems. Also with the Apogee app you can choose your record­ing qual­ity up to 24-bit/96kHz, whereas record­ing video to the iPhone’s Cam­era app seemed to of­fer only 128k AAC, mak­ing the re­sults of record­ings we made to video all the more re­mark­able.

Our 24-bit au­dio record­ings via Apogee were sen­sa­tional. We sat in a hall for a mu­sic con­cert and recorded the lot; again, you have to learn to keep still and face the mu­sic, but the sense of at­mos­phere and hall acoustic were thrilling. And with noth­ing to mon­i­tor — by virtue of the Apogee SoftLimit sys­tem there is no level con­trol ei­ther into iPhone video or the Apogee app — we checked the record­ings and they were kept about 6dB away from clip­ping, so there’s a fair bit of head­room left for trou­ble (or added to the noise­floor, de­pend­ing on your point of view). Im­por­tantly there was no sense of ‘pump­ing’ from auto gain con­trol, and the great plus of this is that there’s no need to keep a con­stant eye on level, and very lit­tle chance of bug­ger­ing up your au­dio.

We as­sume Sennheiser will de­liver non-Ap­ple ver­sions in due course — per­haps USB-C, per­haps ana­logue mini­jack (but per­haps not, given the pro­cess­ing and out­put here are all cur­rently dig­i­tal). The price — not yet an­nounced but with hints putting it in the A$500-700 range — is not in­signif­i­cant for your av­er­age punter keen just for a play, but for any­one se­ri­ous about cre­at­ing im­mer­sive record­ings for video, Sennheiser has de­liv­ered a semi-pro­fes­sional bin­au­ral record­ing tool for a re­mark­able price. Away with your dummy head Mr Neu­mann; Sennheiser’s AMBEO Smart Head­set means we can now use our own.

CES 2017: vis­i­tors queued for a mere minute of AMBEO. Insets: Dr An­dreas Sennheiser presents AMBEO to the IFA Global Press Con­fer­ence; our Ed­i­tor lis­tens in us­ing the AMBEO Smart Head­set.

Mu­sic by Pink Floyd, sound by AMBEO: The Pink Floyd Ex­hi­bi­tion ‘Their Mor­tal Re­mains’ is run­ning at the V&A in Lon­don, with an AMBEO 9.1 pre­sen­ta­tion of their 2005 Live 8 per­for­mance.

ABOVE: The new Sennheiser AMBEO Smart Head­set, spe­cific to Ap­ple iOS de­vices as it uses a Light­ning plug to con­nect. It records di­rect to video sound­tracks in the Ap­ple Cam­era app, or au­dio only to Apogee’s Me­taRecorder.

TOP: Poster for ‘The Massed Gad­gets of Aux­imines’. De­signed by Hipg­no­sis in 1969. Given by Pink Floyd Mu­sic Pub­lish­ing. © Vic­to­ria and Al­bert Mu­seum, Lon­don BELOW: Az­imuth Co-or­di­na­tor used by Pink Floyd; V+A Mu­seum, Lon­don, Im­age An­dreas Prae­fcke

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