Tool Development for Human Audible Spectrum Compensation

Recen Inno a ions in Mecha onics (RIiM) Vol. 2. (2015). No. 1-2. DOI: 10.17667/ iim.2015.1-2/20. 1 Tool De elopmen o Human Audible Spec um Compensa ion F ancisco Gonçal es, Filomena Soa es Algo i mi R&D Cen e Uni e si y o Minho Guima ães, Po ugal [email p o ec ed]inho.p Ví o Ca alho Algo i mi R&D Cen e & *EST Uni e si y o Minho & *IPCA Guima ães, *Ba celos, Po ugal ca [email p o ec ed] José Machado ME RICs R&D Uni e si y o Minho Guima ães, Po ugal [email protected] Abs ac — Communica ion elies on good unde s anding. Humans ela e o each o he h ough isual, audible and ac ile communica ion. I is impe a i e ha he audible communica ion message eaches he ecei e in good condi ions, in o de o keep a heal hy, smoo h and unde s andable speech. The e a e some dis u bances in human speech and communica ion when hea ing damage is p esen . Nowadays, hea ing loss is a equen inju y, caused by noise pollu ion, daily s ess o noisy wo kplaces. Ye , i can be ea ed by se e al ways. This p ojec consis s in de eloping a ool ha cap u es he emi e 's oice audible spec um, il e s he noise and o he equencies, and compensa es he message, enabling he lis ene / ecei e unde s anding. The pu pose o his esea ch is no aimed o subs i u e no compe e wi h hea ing aids in he ma ke , which a e well-de eloped, ce i ied and p esc ibed by O o hinola yngology clinicians. The ocus o his s udy is o iden i y he issues o human hea ing loss and o de elop an algo i hm o hea ing compensa ion by using il e ing echniques in a simula ed en i onmen applied o a hea ing model. Keywo ds— digi al signal p ocessing; hea ing aid; noise il e ing; speech; human ea . I. INTRODUCTION One o he big issues in human unde s anding is he abili y o ealize he sounds so ha i is possible o ansla e he message o he b ain [1]. I is e y impo an o humans o ela e o each o he and eel com o able when communica ing. Hea ing is one o he success’s key. The abili y o hea is c i ical o unde s and he wo ld a ound us as well as in e ac ing wi h each o he . Hea ing impai men is he mos equen senso y de ici in human popula ions and a ec s newbo ns, child en, adul s and elde ly [2], [3]. Howe e , hea ing can be comp omised by issues ha may lead o an ine icien ecep ion o he message. One cause is he hea ing loss. The e a e many causes o hea ing loss. Some imes i is jus a case o a ela i ely simple p ocedu e like cleaning he audible canal in he ea , whe e i is wax accumula ion ha should be emo ed. The e is also he possibili y o an acciden o e en he use o an ibio ics. On he o he hand, when he ne es a e a ec ed he e is no way o eco e . Hea ing loss is one o he causes o social and speech/unde s anding p oblems. The esea ch objec i e o his pape aims o be a i s s ep in o de o apply digi al signal p ocessing (DSP) and il e ing echniques o a hea ing model in o de o enhance speech [4]. The pape is o ganized as ollows: Sec ion II desc ibes he hea ing loss concep ; Sec ion III p esen s he spec um o equencies o hea ing; Sec ion IV shows examples o hea ing aids as well as some mobile applica ions and inally, Sec ion V p esen s he inal ema ks. II. HEARING LOSS When desc ibing hea ing loss, we gene ally look a h ee aspec s: ype o hea ing loss, deg ee o hea ing loss, and con igu a ion o hea ing loss. The e a e h ee basic ypes o hea ing loss: conduc i e, senso ineu al, and mixed. Conduc i e hea ing loss occu s when he sound is no sen easily h ough he ou e ea canal o he ea d um and he iny bones (ossicles) o he middle ea . Conduc i e hea ing loss makes sounds so e and less easy o hea . This ype o hea ing loss can o en be co ec ed by medically o su gically in e en ions. Some possible causes o conduc i e hea ing loss a e [2], [3]:  Fluid in he middle ea om colds o alle gies;  Ea in ec ion (o i is media);  Mal unc ion in he eus achian ube;  Hole in he ea d um;  Too much ea wax;  Ex e nal o i is;  Fo eign body in he ea canal (insec s, among o he s);  Mal o ma ion o he ou e ea , ea canal, o middle ea . Senso ineu al hea ing loss (SNHL) happens when he e is damage o he inne ea (cochlea) o o he ne e pa hways om he inne ea o he b ain. Mos o he ime, SNHL canno be medically o su gically co ec ed. This is he mos common Recen Inno a ions in Mecha onics (RIiM) Vol. 2. (2015). No. 1-2. DOI: 10.17667/ iim.2015.1-2/20. 2 ype o pe manen hea ing loss. SNHL educes he abili y o hea ain sounds. Some possible causes o SNHL a e:  D ugs ha a e oxic o hea ing;  Hea ing loss ha uns in he amily (gene ic o he edi a y);  Aging;  Head auma;  Mal o ma ion o he inne ea ;  Exposu e o loud noise. Mixed hea ing loss occu s when a conduc i e hea ing loss happens in combina ion wi h an SNHL. In o he wo ds, he e may be damage in he ou e o middle ea and in he inne ea (cochlea) o audi o y ne e [5]. Pa ien s wi h SNHL, howe e , also may expe ience inni us, dizziness, o e en ue e igo. Ca e ul ques ioning may e eal ha he pa ien has a speci ic di icul y unde s anding speech. This may be appa en only in ce ain si ua ions, such as when speaking on he phone o in a con e sa ion in a noisy en i onmen o wi h ce ain indi iduals (child en o women whose oices end o be mo e silen and high pi ched). Hea ing loss is an impo an public heal h conce n wi h subs an ial economic and social cos s. In child en, hea ing impai men delays language de elopmen and educa ional p og ess. In adul s, i causes di icul ies in p o essional and social li e as well as sel -es eem. Apa om consequences o he indi idual pe son, hea ing loss also leads o high cos s o socie y. Hea ing impai men can be caused by a numbe o ac o s including in ec ions du ing childhood such as measles, mumps and meningi is, ch onic o i is media, exposu e o excessi e o p olonged noise, head/neck inju ies, use o medica ions such as ce ain ypes o chemo he apies and an ibio ics, indus ial sol en s, congeni al abno mali ies and in ec ions and pe ina al p oblems, ce ain nu i ional de iciencies, gene ic diso de s and aging. Use o hea ing de ices [6] such as aids and cochlea implan s as well as sign language, lip eading and special ampli ica ion sys ems in schools a e s a egies o help a ec ed people manage hei communica ion [7]. III. SPECTRUM OF FREQUENCIES Hea ing is he abili y o pe cei e sounds. Sound occu s o e a wide spec um o equencies. The human ea is sensi i e o a equency band wi hin ha spec um exp essed in decibels (dB). Humans a e capable o hea ing sounds om a ange o equencies. The ange is ypically conside ed o be be ween 20 Hz and 20000 Hz. F equencies highe han 20 kHz a e conside ed as ul asonic, while equencies below audio a e e e ed o as in asonic. Loss o he abili y o hea sound equencies in he no mal ange o hea ing is called hea ing impai men . The e is a di e si y o de ini ions o hea ing impai men , hus, compa ison among s udies is di icul and may be in alid. The de ini ion used by any s udy should always be checked be o e a emp ing o make such compa isons. The Wo ld Heal h O ganiza ion (WHO) de ines disabling hea ing impai men in adul s as a pe manen unaided hea ing h eshold le el (a e age o equencies 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz) o he be e ea o 41 dB o g ea e (WHO, 2001). In child en unde 15 yea s o age, disabling hea ing impai men is de ined as pe manen unaided hea ing h eshold le el (a e age o equencies 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz) o he be e ea o 31 dB o g ea e [5]. Figu e 1 shows he equencies and h eshold le els o hea ing [8]. Fig. 1 – Hea ing Th eshold Le els [8] Figu e 2 shows a ypical audiome ic examina ion o a pa ien wi h mild o mode a e hea ing loss. Fig. 2 – Audiome ic Examina ion Tes (example) In his example, he e is no di e ence be ween he ai conduc ion and he bone conduc ion h esholds; i indica es ha he hea ing loss is due o a p oblem in he cochlea. This is he mos common ype o hea ing loss in adul s and i is known as a senso ineu al hea ing loss [9]. Recen Inno a ions in Mecha onics (RIiM) Vol. 2. (2015). No. 1-2. DOI: 10.17667/ iim.2015.1-2/20. 3 IV. HEARING AIDS Hea ing aids can be applied o o e come his impai men . Because hea ing aids oday a e digi al and p og ammable, he ampli ica ion can be ine- uned and ailo ed o each wea e . Basic hea ing aids usually equi e some manual adjus men s depending on he ype and deg ee o loss expe ienced by a pe son. Basic hea ing aids allow o some cus omiza ion bu a e limi ed in he amoun o adjus men s o i unusual pa e ns o hea ing loss. Ad anced hea ing aids o e se e al di e en le els o echnology. As he le el o echnology inc eases, hea ing de ices a e mo e au oma ic, equipped wi h mo e ea u es and allow o a mo e-pe sonal expe ience. Some o he g ea es ad an ages o digi al signal p ocessing in hea ing aids applica ions a e [10]:  Gain P ocessing ( he po en ial o inc eased audibili y o sounds o in e es wi hou discom o );  Digi al Feedback Reduc ion (moni o o eedback while he lis ene is wea ing he hea ing aid);  Digi al Noise Reduc ion (in ended o educe gain in he low equencies o bandwid h when noise is de ec ed);  Digi al Speech Enhancemen (a ela i ely new o hea ing aid, i is in ended o imp o e empo al o spec al con en o speech in o de o enhance speech);  Di ec ional Mic ophones and DSP (abili y o di ec ional hea ing aids o imp o e he e ec i e signal- o-noise a io p o ided o he lis ene );  Digi al Hea ing Aids as Signal Gene a o s. The hea ing aids p oduced oday u ilize wi eless echnology. This allows wo hea ing aids o ope a e oge he as one comple e sys em, ins ead o ac ing as wo independen de ices. Addi ionally, wi eless echnology gi es hea ing aid use s a g ea e abili y o cus omize hei expe ience and p og am hei de ice. Wi eless hea ing aids a e o en capable o wi elessly communica ing wi h ex e nal de ices as well, as Blue oo h echnology. Blue oo h enables hea ing aid wea e s o connec pe sonal elec onic de ices such as mobile phones and s eam signals di ec ly o he hea ing aid. Wi eless hea ing aids can use compa ible assis i e lis ening de ices, o en called s eame s, o p o ide a communica ion link be ween he wi eless echnology in he hea ing aids and any Blue oo h- enabled de ice. A. Types o Hea ing Aids While hea ing aids can be spli in o wo b oad ca ego ies – in- he-ea s yles (ITE) and behind- he-ea s yles (BTE) – he e a e se e al ypes a ailable wo n in di e en loca ions in o behind he ea , allowing he wea e o ind he mos com o able and bene icial i . The ollowing hea ing aid ypes a e conside ed in- he-ea s yles and a y om comple ely in isible and in he canal o on he ou e edge o he ea bowl[11][12]:  BTE – Behind he Ea . Placed behind he ea . Ve y o en used in child en whe e sa e y is conce ned (Fig. 3). Fig. 3 - BTE – Behind he Ea  Behind-The-Ea Aid (Open Fi ing). Ve y simila o he BTE bu wi h small and anspa en ube o cosme ic easons (Fig. 4). Fig. 4 – Behind The Ea (open i ing)  ITC – In The Canal. De ice pa ially inside he canal (Fig. 5). Fig. 5 – ITC – In-The-Canal  CIC – Comple ely in he canal. Almos as ITC, his ype is enclosu e in a small box and comple ely inside he canal. They o e he bes solu ions o cosme ic pu poses (Fig. 5). Fig. 5 – CIC – Comple ely In he Canal  ITE – In The Ea . All pa s a e ou side he canal. This ype is usually used by hose how a e no com o able wi h CIC models (Fig. 6). Fig. 6 – ITE – In-The-Ea Recen Inno a ions in Mecha onics (RIiM) Vol. 2. (2015). No. 1-2. DOI: 10.17667/ iim.2015.1-2/20. 4 B. Hea ing Aids in Mobile Applica ions The e a e also hea ing aids a ailable as mobile applica ions whe e i is possible o con ol some pa ame e s ia Blue oo h [13], [14] (Fig. 7-8). These mobile applica ions a e used o access o a as a ay o pa ame e s con olling, ia Blue oo h. I is possible o con ol olume, spa ial cus omized con igu a ions, among o he s. They a e ee o cha ge and in ended o use wi h Siemens hea ing aid p oduc s (Fig. 7) o GN ReSound (Fig. 8). Fig. 7 – TouchCon ol App e easyTEK App om Siemens Recen Inno a ions in Mecha onics (RIiM) Vol. 2. (2015). No. 1-2. DOI: 10.17667/ iim.2015.1-2/20. 5 Fig. 8 – ReSound Con ol Mobile App om GN ReSound, a ailable o iOS. The e a e some ools, in he o m o applica ion o mobile de ices, usually limi ed, wi h some es s a ailable so ha he use ha e an idea o his hea ing si ua ion. Some applica ions (almos all o hem a e paywa e) can be used as a hea ing aid as mobile’s headphones and mic ophone (Fig. 9 o Fig. 11, cou esy o BioAidP ojec , Uni on Limi ed and Ginge Labs, espec i ely). This applica ion is in ended o gi e an audiome ic es so ha he use may ha e an app oach o his/he hea ing loss and hus, i necessa y, con ac he O o hinola yngology clinicians o e alua e he p oblem. Th ough a simple in e ace, he use can adjus a ew pa ame e s o enchance hea ing. Fig. 9 – Sc eensho om AUD1 [15], om BioAid P ojec , a ailable o iOS de ices. Fig. 10 – uHea [16] om Uni on Hea ing Limi ed Fig. 11 – soundAMP R [17] om Ginge Labs V. FINAL REMARKS The esea ch objec i e is o apply DSP and il e ing echniques o a hea ing model in o de o enhance speech. Some echniques should be used like noise cancela ion, ampli ica ion, comp ession, equency anspo a ion [18], [19]. Hea ing aids a e based on complex algo i hms and well de ined s uc u es. Algo i hms in ended o simula e he human audi o y sys em ansla ing beha io s. Hea ing aids canno o e come he pe cep ual dis o ions caused by hea ing loss bu enables he use o unde s and he speech in a be e way [20- 23]. Recen Inno a ions in Mecha onics (RIiM) Vol. 2. (2015). No. 1-2. DOI: 10.17667/ iim.2015.1-2/20. 6 Acknowledgmen This wo k has been suppo ed by FCT - Fundação pa a a Ciência e Tecnologia in he scope o he p ojec : PEs - UID/CEC/00319/2013. Re e ences [1] Heinz G. Gockle , Henning Pude , Hugo Fas l, S en E ik No dholm, To s en Dau, Wal e Kelle mann, Edi o ial Digi al Signal P ocessing o Hea ing Ins umen s, Hindawi Publishing Co po a ion, EURASIP Jou nal on Ad ances in Signal P ocessing Volume 2009, A icle ID 898576, 3 pages doi:10.1155/2009/898576. [2] Conse e Ene gy G een, Unde s anding Noise Pollu ion, h p://www.conse e-ene gy- u u e.com/causes-and-e ec s-o -noise- pollu ion.php (access in Feb ua y 2015). 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