Objective evaluation of upright and grand pianos by measuring play-bench

43 ACC JOURNAL 2018, Volume 24, Issue 1 DOI: 10.15240/ ul/004/2018-1-005 OBJECTIVE EVALUATION OF UPRIGHT AND GRAND PIANOS BY MEASURING PLAY-BENCH Jana U bánko á VÚTS, a.s., Measu emen Depa men , S á o ská 619, Libe ec XI - Růžodol I, 460 01 Libe ec, Czech Republic e-mail: jana.u ba[email p o ec ed] Abs ac This a icle desc ibes he measu ing equipmen which is used in he objec i e e alua ion o pianos. This equipmen in he o m o a play-bench eplays each key o he piano keyboa d sepa a ely, making i possible o measu e he acous ics such as sound p essu e le el and one e e be a ion leng h. Objec i e e alua ion o such a complica ed ins umen as he piano is a e y complex ask. An in eg al pa o e alua ion is he psychoacous ic dimension and he con e sion o subjec i e pe cep ions in o objec i e acous ical alues. Keywo ds Piano; Play-bench; S iking pins; Acous ics; Psychoacous ics. In oduc ion The piano is a e y complica ed musical ins umen and i is ela i ely new, i s in oduced in he 18 h cen u y and e ol ing o he cu en appea ance o he g and piano in 19 h cen u y [3]. In compa ison wi h o he musical ins umen s, he piano o e s huge possibili ies o playing. The eno mous ange o loudness consis s he name i sel – “piano o e” (piano = quie ly, o e = loud). The adi ional manu ac u e o musical ins umen s is a highly p es igious handc a , and amous p oduce s base hei epu a ion on p ecise handmade wo k. So when hey a e assessed, i canno be p ac ically ci cum en ed wi hou a subjec i e e alua ion. Simply he e alua ion o he musical sound i sel is e y na ow specializa ion [1] and [2]. I he manu ac u e wan s o ind ou he quali y o hei ins umen , hey a e p ac ically always dependen on p o essional playe s’ opinion. This o m o eedback is leng hy and uneconomical in many ways. Fo he manu ac u e i is e y complica ed o ound up mo e playe s oge he , ensu e equal condi ions o e e yone and compa e hei answe s, which a e o en e y speci ic. Nex p oblem is he ac ha playe s (especially pianis s) a e o en unable o sepa a e he pe cep ion o he sound om he pe cep ion o unning he mechanics; i is said ha “ hey hea wi h hei hands”. I is he e o e inc easingly necessa y o manu ac u e s o e alua e hei ins umen s in an objec i e way so ha hey can compa e each o he and go o wa d wi h hei own de elopmen . The b anch o science called psychoacous ics deals wi h he subjec i e pe cep ans e in o objec i e da a and use he knowledge o human pe cep ion [6]. 1 Resea ch Objec i e In he i s place, he esea ch objec i e is o mode nize and ebuild he o iginal play-bench o new measu emen equi emen s and inding a sui able measu emen me hodology. 44 2 Measu ing Equipmen Big ad an ages o objec i e measu emen a e speci ica ions o clea ly and epea able measu emen condi ions and esul s p esen ed by a single alue. The e alua ion and compa ison o single ins umen s becomes much easie . A he end o he 1960s, measu ing equipmen [5] was de eloped in he S a e School o Music in Wa saw o Czechoslo ak musical ins umen s. This de ice consis ed mainly o a bench used in Pe o company o esea ch and de elopmen [4] in he 1990s. In he las wo yea s, he play-bench was eno a ed and upg aded o o e g ea e possibili ies o measu ing pianos. 2.1 The O iginal Play-Bench o Pe o The o iginal play-bench (shown in Fig. 1) was composed o aluminium ail on which wo s iking pins we e mo ed - one o he whi e keys and he second o he black ones. A sys em o me allic con ac s on he ail allowed he pin o s op abo e he pa icula key. Then he key was exci ed by he s iking pin wi h a de ined powe . The pins consis ed o a pai o elec omagne s and a se o wo a i icial inge s. The a i icial inge s we e conical in shape and we e made o e lon. The keys oke was pe o med by he ee all o he pin on he key. The mo emen o he pins and he measu emen was ealized by he con ol sys em (Fig. 2) emo ely. Sou ce: Own Fig. 1: O iginal equipmen cons uc ed in 1960s Sou ce: Own Fig. 2: The con ol sys em o measu emen se ings o he o iginal play-bench 45 Because o obsole e sys em, long ime inac i i y and need o wide se ing o play-bench, he measu ing equipmen was ebuil o he need o he Pe o company, in ol ing mode nizing he con ol sys em and adap ing i o easie p og amming. 2.2 Rebuilding and Mode niza ion o he Play-Bench Only he se o elec omagne s and bo h pins we e used om he o iginal de ice and hey we e also pa ially modi ied. The aluminium ail was eplaced by a s eel gi de and uni e sal clamping b acke s which hold he equipmen on o he piano. The pins a e anspo ed along a ci cula slide way and mo e using a oo hed bel and a s eppe mo o . The new play-bench is shown in Fig. 3. An indus ial compu e (PLC) is used o con ol and se he measu emen (shown in Fig. 4). This allows us o change he se ing o he measu ed ange and he play mode, he ime o he keys oke and he ime be ween he pins mo emen and he keys oke. The en i e de ice was modi ied in pa icula o measu e he ull dynamic ange o he ins umen . The keys oke is pe o med by ee all, so i is possible o con ol and a y i s impac o ce only by addi ional weigh s and adjus men o he heigh o he a i icial inge s. Compa ed o he o iginal adjus men o he pins heigh , when i was necessa y o change he in e nal s uc u e o he pins, he heigh (2-20 mm abo e he keyboa d, including he possibili y o adding weigh ) is se di ec ly by he a i icial inge s. Sou ce: Own Fig. 3: The ebuil and mode nized play-bench 46 Sou ce: Own Fig. 4: The indus ial compu e o con ol and measu emen se ing Sou ce: Own Sou ce: Own Fig. 5: Scheme o he a i icial inge s uc u e: ed – e lon ape, u quoise – silicone head, da k g ay – ein o cing sc ew Fig. 6: The de elopmen o a i icial inge s o he a le : o iginal a i icial inge made o e lon, o he a igh : he inal o m o a i icial inge made o addi ion silicone and e lon apes 2.3 The S iking Pins As has been said, one o he impo an claims o he mode niza ion was he abili y o play he keys in he ull dynamic ange o he ins umen . This is mainly in luenced by he appea ance o he a i icial inge s. Many shapes and ma e ials we e es ed in he pas , pa icula ly because o he du abili y o he ma e ial and he abili y o easily slip o e he key su ace. O iginal inge s we e cons uc ed wi h he be elled cylind ical pins om e lon. This solu ion had lo s o ad an ages - he e was no de o ma ion a e epea ed use, he loca ion o s iking on he key was su icien ly de ined, and ic ion was minimized. Bu i was unusable o he lowes dynamics because o he ha d ma e ial ha made a lo o noise by he keys oke. 47 The e o e, new a i icial inge s we e made o so addi ion silicone, which is e y close o he silicones used in o hopaedics and p os he ics. A hin e lon oil is also a ached o he su ace o he silicone inge o ensu e easy slipping on he key. A simple diag am o a silicone a i icial inge is shown in Fig. 5 and he de elopmen o he a i icial inge s hemsel es is illus a ed in Fig. 6. 3 The Me hods o Resea ch Me hods o esea ch ep esen mainly measu emen s o ins umen s hemsel es, e i ica ion o hese measu emen s and subsequen compa ison o achie ed esul s. 4 The Measu emen A e he inal adjus men and modi ica ion o he measu ing play-bench, h ee pianos we e measu ed – wo up igh pianos and one g and piano. All ins umen s we e measu ed in semi- anechoic chambe wi h wo mic ophones posi ions – objec i e and “psychoacous ics”. The i s (objec i e) posi ion is di e en o up igh pianos and o g and pianos. Fo he up igh piano, he mic ophone is placed 1 m high a a dis ance o 1 m on he axis pe pendicula o he su ace o he soundboa d and in case o he g and piano; he mic ophone is posi ioned in he ex ension o he igh edge o he ins umen , 160 cm high and pa allel o he opened main lid. The posi ion o he mic ophone o he psychoacous ic measu emen is in he loca ion o he playe . 4.1 Measu emen Se ings Fi e speci ica ions o dynamics o he measu emen we e de e mined. These speci ica ions di e ed in he heigh and weigh o he s iking pins wi h he same s ep. I was ound ha he maximum weigh o he s iking pin o he black keys was lowe han o he whi e keys because o di e en inne s oke mechanism and ea men o he key su ace i sel . While he maximum weigh o he addi ional weigh s is gi en by he play-bench op ions, o by he elec omagne s op ions, he minimum weigh is gi en by he possibili ies o indi idual ins umen s and mus be de e mined o each ins umen indi idually. Replaying o keys was done in he “All” play-mode, so ha all 88 keys on he keyboa d we e eplayed sequen ially. 4.2 E alua ion Fo objec i e compa ison o each ins umen , i is necessa y o educe a la ge amoun o da a (88 keys) o a single numbe ha e alua es he en i e ange o he ins umen o (be e ) o h ee alues co esponding o dis ibu ion o he ange acco ding o Tab. 1. Tab. 1: Di iding he keyboa d ange in o app oxima ely h ee equal g oups Dis ibu ion Tone ange (Ge man no a ion) O de o ones on he play-bench bass A2 – d 88 – 59 al o dis – gis2 58 – 29 descan a2 – c5 28 – 1 Sou ce: Own The ange o piano dynamics is acco ding o he li e a u e om 40 dB o 100 dB. Tab. 2 shows a mo e de ailed dis ibu ion. 48 Tab. 2: Theo e ical ange o piano dynamics Dynamics Sound p essu e le el [dB] Tole ance [dB] ppp (piano pianissimo) 40 ± 5 pp (pianissimo) 50 ± 5 p (piano) 60 ± 2.5 mp (mezzopiano) 65 ± 2.5 m (mezzo o e) 70 ± 2.5 ( o e) 80 ± 5 ( o issimo) 90 ± 5 ( o e o issimo) 100 ± 5 Sou ce: [7] The ime eco ds o he sound p essu e signals we e ob ained by he measu ing sys em. F om hese ime eco ds, he wa e o ms o sound p essu e le els we e e alua ed, weigh ed by he il e A and exponen ially a e aged wi h a ime cons an o  = 1/8 s. This se ing ep esen s he acous ic emission as pe cei ed by he human ea . A e ha , he maxima o sound p essu e le els o each key we e ound in di e en dynamics and he o e all "loudness" o indi idual pianos was e alua ed. The e m o loudness is no de ined he e by psychoacous ic me ic bu o he compa ison o ins umen s i is su icien o de ine he maximum sound p essu e le el. Toge he wi h he wa e o ms o ones, he one e e be a ion leng h o he indi idual keys and he whole ins umen we e de e mined. An example o he one e e be a ion leng h o ones a4 (descan ), a1 (al o) and A1 (bass) is shown in Fig. 7. Sou ce: Own Fig. 7: The sound p essu e le el depending on ime, ones a4 (descan ), a1 (al o) and A1 (bass) (le o igh ) in Ge man no a ion Tab. 3 o 5 show he esul s o he o al sound p essu e le el Lp (A) and one e e be a ion leng h o di e en dynamics o e he en i e ins umen s ange. The “D1” ep esen s he lowes dynamic and “D5” he loudes one. 49 Tab. 3: To al sound p essu e le el and one e e be a ion leng h o di e en dynamics o e he en i e ange o up igh piano 1 Up igh piano 1 Mic ophone 1 (objec i e) Mic ophone 2 (psychoacous ic) Dynamics Lp(A) [dB] [s] Lp(A) [dB] [s] D1 64.52 4.57 61.38 3.94 D2 76.76 8.28 70.32 6.01 D3 82.02 9.91 74.82 7.51 D4 84.81 10.79 77.48 8.05 D5 86.42 11.13 79.02 8.36 Sou ce: Own Tab. 4: To al sound p essu e le el and one e e be a ion leng h o di e en dynamics o e he en i e ange o up igh piano 2 Up igh piano Mic ophone 1 (objec i e) Mic ophone 2 (psychoacous ic) Dynamics Lp(A) [dB] [s] Lp(A) [dB] [s] D1 63.79 4.71 57.40 3.37 D2 77.03 8.38 67.31 5.51 D3 81.19 9.57 73.76 7.67 D4 83.87 10.22 76.34 8.39 D5 85.83 10.90 78.26 8.92 Sou ce: Own Tab. 5: To al sound p essu e le el and one e e be a ion leng h o di e en dynamics o e he en i e ange o g and piano G and piano Mic ophone 1 (objec i e) Mic ophone 2 (psychoacous ic) Dynamics Lp(A) [dB] [s] Lp(A) [dB] [s] D1 65.60 5.93 61.38 3.94 D2 78.17 9.45 72.44 7.15 D3 83.87 11.57 78.21 8.88 D4 86.88 12.52 81.17 9.50 D5 88.64 12.93 82.80 9.94 Sou ce: Own Conclusion The imp o ed and upg aded play-bench allows us o eliably eplay each key o he piano keyboa d wi h a de ined and s anda dized keys oke in he dynamic ange om piano (p) o o issimo ( ), which is su icien o gene al piano a ings. Limi a ions o he lowes dynamics a e mainly due o he ins umen s hemsel es and hei inne mechanisms. The play- bench is also uni e sally applicable o any ype o up igh o g and piano hanks o he uni e sally adjus able cons uc ion. Two up igh pianos and one g and piano we e measu ed and e alua ed using he play-bench. Based on he sound p essu e measu emen , he o e all sound p essu e le el (o e all “loudness”) o he indi idual ins umen s and he one e e be a ion leng h we e e alua ed o i e de ined dynamics. The co ec unc ionali y and limi s o he play-bench we e e i ied du ing he measu emen . 50 Acknowledgemen s This p ojec has been suppo ed by he CTU esea ch p ojec SGS16/221/OHK3/3T/13 Measu emen , modelling and e alua ion me hods in acous ics and by he Czech Minis y o Educa ion, p ojec LO1213. The au ho would also like o hank he company Pe o . Li e a u e [1] TERHARDT, E.: Psychoacous ic e alua ion o musical sounds. Pe cep ion & Psychophysics. 1978, 23(6), pp. 483–492. ISSN 0031-5117. DOI: 10.3758/BF03199523 [2] SYROVÝ, V.: Hudební akus ika. 3. doplněné ydání. P aha: Akademie múzických umění, 2013. Akus ická kniho na Z uko ého s udia Hudební akul y AMU. ISBN 978- 80-7331-297-8. [3] GIORDANO, N. J.: Physics o he piano. Ox o d: Ox o d Uni e si y P ess, 2010. ISBN 0199546029. [4] NOSEK, J.; RAFFAJ, A.: Objek i ní měření akus ických las nos í pian. Výzkumně- ý ojo é s ředisko s. p. Pe o , 1991. [5] BOBILEWICZ, Z.: Uni e salna LAWA Pomia o a do Poloau oma ycznej Kon oly Pianin. Wa zawa: AM Chopina, 1970. [6] MELKA, A.: Základy expe imen ální psychoakus iky. 1. yd. P aha: Akademie múzických umění P aze, 2005. ISBN 80-7331-043-0. [7] KURFÜRST, P.: Základy hudební akus iky. B no: Masa yko a uni e zi a, 2000. ISBN 80-210-2333-3. Ing. Jana U bánko á 51 OBJEKTIVNÍ HODNOCENÍ PIANIN A KLAVÍRU POMOCÍ PŘEHRÁVACÍ LAVICE Ten o článek popisuje měřicí zařízení použí ané při objek i ním hodnocení pian. Zařízení podobě přeh á ací la ice samos a ně přeh aje každou klá esu na kla ia uře a umožní ak změření akus ických las nos í, jako je hladina akus ického laku a délka dozní ání ónu. Objek i ní hodnocení ak složi ého nás oje, jako je kla í , je elmi komplexní úkol. Nedílnou součás í hodnocení je psychoakus ický ozsah a přeměna subjek i ního nímání na objek i ní akus ické hodno y. OBJEKTIVE BEWERTUNG DER PIANINOS UND KLAVIERE MIT DER MESSBANK Diese A ikel besch eib ein Messge ä , das bei de objek i en Bewe ung on Kla ie en e wende wi d. Dieses Ge ä in Fo m eine Messbank übe spiel unabhängig jede Tas e de Kla ie as a u und e möglich die Messung akus ische Eigenscha en wie Schalld uckpegel und Tonausklanglänge. Die objek i e Beu eilung eines so komplizie en Ins umen s wie des Kla ie s eine seh komplexe Au gabe. Ein wesen liche Bes and eil de Bewe ung is die psychoakus ische Dimension und die Umwandlung subjek i e Wah nehmungen in objek i e akus ische We e. OBIEKTYWNA OCENA PIANIN I FORTEPIANÓW ZA POMOCĄ ŁAWKI ODTWARZAJĄCEJ W niniejszym a ykule opisano u ządzenie pomia owe używane do obiek ywnej oceny pianin. U ządzenie w pos aci ławki od wa zającej od wa za oddzielnie każdy klawisz klawia u y, umożliwiając pomia cech akus ycznych akich jak poziom ciśnienia akus ycznego i długość ezonansu dźwięku. Obiek ywna ocena ak skomplikowanego ins umen u, jakim jes o epian, jes ba dzo kompleksowym zadaniem. In eg alną częścią oceny jes zak es psychoakus yczny i konwe sja subiek ywnego odbio u na obiek ywne wa ości akus yczne.