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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
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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.
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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.

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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.
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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 .
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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
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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.