um sort of the delay a we come to my presentation on a spatial temporal signal was multichannel acoustic a cook relation uh that's or like like to give an outline of my presentation i would introduce my presentation by you brightly maybe on the problem of multichannel acoustic echo it in constellation a a a a a a that a a approach i i i would present yeah in my lecture can say uh massive multichannel reproduction systems and for that i would like to we interviews some basic properties of a method of the channel reproduction systems a that i one introduced a the novel approach for spatial can problem preprocessing and give a to or uh um a a roles of this i or practical implementations and after that i to with no so i think you have a seen similar a block yet from in this section so forth that i i is suppose you know what is says you know so we have here just a a a a a and and and you and strong and i i yeah all what acoustic E constellation it to create a replica of sandy the or in room um model model as um my F I R filter and the that got of that my my by a filter okay are usually a minute by by at least squares optimized addition the optimal solution right a or is given by the you know how to equation also known and a normal equation here we have that in terms of are are X it's which uh if uh inverse of the correlation metrics of the loudspeaker the signals in then used and role and are it's Y D notes that a cross correlation metrics tricks between the loudspeaker signals and the microphone signals he's any and room um in in practise there at the filters are the term and at optimally because that acoustic of the own could be i of over at a time is that it can be shown that that's speed of con veterans oh adaptive filters depends of on that i gains spread of the autocorrelation metrics and for some fleeting in a typical uh a for the the like communication scenarios we have only you if source source as in the are end room and Z sources are right by many loudspeakers speakers in there near and room hence we have a and ill conditioned are X six and how to cool where just problem that i do yeah is to preprocessed process that allows loudspeaker signal in that near in troll in order to decorrelate the channels with rest but to each other that the preprocessing techniques have to fulfil fill at least in three but and first one is for for of that convergence enhancement that's second requirement if is that a preprocessing technique that doesn't introduce all people um uh the distortion on the signal and also that there preprocessing technique doesn't in use in the yeah uh compute uh uh audition them complexity complexity factors for to oh for us T your isn't to their production systems you can find many approaches for preprocessor loudspeaker signals a and T i mention only two the first one was introduced by the the is T and to the idea oh it is to rate up to introduce nonlinearities as the signal this approach feature a very low complexity but that distortion that it in uses bit come quite to a problem for high quality signals for for them for music conference or something like that and uh and a second to a perceptually when motive that up holds well introduced used by you can hear to and the i B is this one have for use on a frequency selective phase modulation of the a loudspeaker signal so the uh he of of that a loudspeaker signals are decomposed in in bands in the by means of uh analysis filter and the sub-band signals uh a or the face of the subband signals and modified in a frequency dependent am modulating signal and the now i a to come to the second point and what is like to introduce that massive multichannel reproduction systems the sound field sinc to is this systems in at is that to use this of the sound field to put used might have the actual source S with an an extended yeah yeah V using and i'm bill of a speakers on the boundary of that area here the the delta be in that go this many techniques um you for solving this problem and the we some of them are are this specialised on specific a a is you for example is that near field compensated tie i what i'm based on it which is the a specialised on a circle and say and and is we have also for a planet and lean yeah and i is is that so called it's spectral division method it's the M and the more or less is more one uh and i rate in an independent technique technique it is is a a a a a W F S is the wave field synthesis techniques which words for linear plan a and other convicts and i image for sure as a a low or to kill implementations of for sound field sent to just are discrete and therefore the except the the except if something like an aliasing frequency and we can say that the control ability of the sound field is available only up to a given frequency and here we see use this simulation one and linear very with twenty loudspeakers speaker and here at the frequency have it it's hundred have which is below the and you in frequency of of this yeah right that wave front can be response set correctly and here for the two thousand a time the test which i all the figure that L in frequency we see that that where front and a be reconstructed firstly so and the two our problem that we like to implement and uh uh acoustic echo canceller for such a set up who with with massive multichannel systems this problem is a challenging not only be a is that is the autocorrelation matrix as are are very last and in condition when addition uh it can be shown that the someone you to synthesized by a massive multichannel the production techniques are very sensitive to any day deviation on the tiring signals uh do you to build a preprocessing and to hear it should be not that is that best section or from from and uh so i got the point of view that's a perception of that is synthesized wave fields by sound and to the synthesis techniques are completely i is completed different the then of stereophonic funny the based techniques and haynes any temporal preprocessing should be avoided the so we can do and a preprocessing techniques and how to cope with this problem and therefore we have it a novel approach for spatial or temporal i E C preprocessing and this is is never a novel approach basis actually on how a very all with them namely prevention is better than Q and what we would like to do what we do would like to do if actually two that but here and in addition and that the channel and uh processing you it is that a i is that a loudspeaker signals in such a way that is that a wave feel is set to zero euro the positions of the i ones so we light two D lee is are listening yeah yeah in two two the ones one own is quite where some microphone and i is supposed to be and then another listening yeah yeah where is the desired feel is a construct a lee is the but problem of creating own on i i'd this not new and the in the literature you can find many start days on it and here i have listed only some also but to here i i'd like to introduce and you and a local approach for a at uh the uh creating zones of quiet with linear and i this approach is best it just straight by uh uh but is illustrated but be thing on the method of spectral division method and therefore i would like two just give that say or tickle be six of that mm method and in is it is this method assume assume what or or to be is is actually one the idea that some wave feel reproduced produced by a linear distribution of the second outing source of can B it it's press by a convolution of the thinks signals of is that a second so that's was the green function of that services and that that are green functions can be and just to as a spatial temporal transform domain to but also a secondary source in the following derivation we will restrict our configuration on a reference line and the uh what if we do that we can see is that we have a one time in the novel the um the one dimensional convolution and for it exact convolution theorem holds so if we do a fourier yeah transform we get a multiplication and to by to be an announcement we get an expression for that mean function for uh so and uh here is idea for creating the role of quite is actually just by multiplying that desired wave field white i by L we don't by a specific we and the if we we be formally that in the wave number can mean we get them a and expression for the desired wave field in the wave number mean and we get after that an expression for the subscribing signals that to to prove that our approach can i is applicable to a a acoustic it constellation we have computed that attenuation innovations that can be done by this approach by creating as a of quite and we uh and put here and microphone and right that's in an we shouldn't with that a point which is supposed to be in the sweet spot and we got an at wishing up to seventy D V which is comparable was to become yeah it cool return last enhancement quite S i have a shown hmmm is that uh the control ability of there wave if it's can be done only up "'cause" the anything frequent and frequency and they for for higher frequencies acoustic it go constellation or a typical acoustic echo equal constellation must be still a applied and therefore for we propose here at divide in the or or a yeah i don't like or decomposing "'cause" the signal into to sub bands and for a lower frequencies just to so right to use our approach and for i higher frequencies to apply and the acoustic you constellation yeah and say that approach can be also uh use well with the equal colour and is which are more interest interesting for spatial audio reproduction systems for example by applying that output but it represented presented by a problem and i come to the conclusion and the intuition of my work well to show that is that at to the acoustic you constellation can be done in a a distributed manner on the loudspeaker a side and on some microphone side and not only at it has been the done does on the microphones side and i have shown one yeah um a method to can for creating zones of quiet as linear allows loudspeaker i and is i have sons that that imitation that we have a yeah is and and on that uh anything frequency of the loudspeaker a rate therefore for frequency selective implementation should be done thank uh we have time for questions two T uh i would you like i got got a scalar oh i was wondering if you have oh people in side you're or right would they change uh as they move around with you the quiet the G yeah actually we yeah we have um um consider only that analytical cave yeah and we have a set for the right functions a free feel yeah and hmmm as the for the free field the green function but for a practical of imitation should be implemented in now at that man and so so we will have a just a mismatch between that's that's supposed green function and a real one green function and therefore we will not get is that performance of going to quite on as we have my my uh what would the geometry of a relationship of the microphone and a loudspeaker would like thing to the lead the microphones you're the low result just in you know maybe you consider a circle uh you know where have you thought about that would be a very sad or a microphone geometry we we are independent actually from the microphone german trace a a always a loudspeaker to and we have simulated with omnidirectional lower speed oh okay and you did you in room reflections so so i just want is the low frequency stuff you you do by well making the by yeah it becomes an active noise can a problem if you microphones phones in the five you can use that able to full the null at a point to the mic and an active noise relation yeah maybe it's is a good idea i now we have a we haven't considered that it seems to be with a i yeah think is that when you are no you the microphone was it microphone and the the markers yeah that will not that will not that it is are yeah exactly they were not so i yeah yeah actually therefore why have someone is that it is more interesting to yeah to thing to do that consideration with in closing a right because uh can one can include yeah because we can define here at someone of quite which is restricted on the position of the microphone so only at a microphone position you do you wouldn't here anything but in the listening position so for example if you can imagine that if that is there a conference room and here's a table able with a microphone is on it so it two would be with B actually very practical for the people to put their head on the table the city if they hear something on a yeah that is actually i a well thank you very much to little a is off thus