Perception and Production of Staccato - Haskins … and Production of Staccato Articulation on the Piano Bruno H. Repp ... legato is indeed characterized by a small overlap in key

Perception and Production of StaccatoArticulation on the Piano

Bruno H. Repp

Haskins Laboratories

Unpublished manuscript (completed October 1998)

Bruno H. ReppHaskins Laboratories270 Crown StreetNew Haven, CT 06511-6695

Tel. (203) 865-6163, ext. 236FAX (203) 865-8963e-mail: [email protected]

Repp: Staccato articulation Page 2

Abstract

Skilled pianists were requested to interactively adjust note (i.e., key

depression) durations in simple sequences, played under computer control on a

digital piano, so as to sound optimally staccato (perception task) and to perform

analogous sequences with staccato articulation on the same instrument as well as on

a real piano (production task). The independent variables were tempo, register, and

pitch step size; also, in production, hand and sequential position. Note durations

increased significantly as tempo decreased in both perception and production, but

there were large individual differences in the magnitude of these effects. Note

durations were longer in production than in perception, and longer on the digital

than on the real piano. In perception but not in production, low notes were assigned

shorter durations than high notes. There were complex effects of sequential note

position, in part due to metrical structure. The results illustrate some of the factors

that influence staccato articulation, and they also reveal some discrepancies between

perception and production of staccato. In particular, it seems that produced staccato

is not necessarily perceptually staccato.


INTRODUCTION

Most musical instruments give the player control over the physical durations

of tones, be it by releasing keys, lifting the bow from strings, stopping airflow, or

damping vibrations with the hand. On these instruments, therefore, there are two

ways of articulating successive tones: When one tone is terminated near the

beginning of a following tone, the tones are perceived as connected or legato; but

when the first tone is terminated earlier, so that a noticeable gap occurs between the

tones, they are perceived as separated or non-legato.

The perceptual and kinematic distinction between legato and non-legato on

the piano has been the subject of several recent studies (Kuwano, Namba, Yamasaki,

& Nishiyama, 1994; Repp, 1995, 1997). On the piano it is possible to release the key

for one tone after the key for a following tone has been depressed, and optimal

legato is indeed characterized by a small overlap in key depressions (the key overlap

time or KOT). The acoustic overlap of the tones is even more substantial, due to the

post-release (damped) decay of piano tones, which may extend over several

hundreds of milliseconds (Repp, 1995, 1997).

Repp investigated legato articulation in simple ascending and descending

scales and arpeggi, and he hypothesized that the KOT would depend on certain

acoustic properties of piano tones. For example, high tones decay faster than low

tones while they are sustained (Martin, 1947; Repp, 1995, 1997), so that—given equal

durations of key depressions—they have a relatively lower amplitude at the time of

key release and hence a shorter post-release decay time than low tones. Also, a long

tone obviously decays further than a short tone of the same pitch while the key is

depressed, so that the former has a shorter post-release decay time than the latter.

Thus it was predicted that KOTs for optimal legato would be longer in sequences of

high or long tones than in sequences of low or short tones, on the assumption that a


constant degree of acoustic (or rather auditory) overlap would be aimed for. Both

predictions were confirmed in a perception task that required listeners to

interactively adjust the KOTs of a tone sequence until it sounded optimally legato.

When pianists played identical sequences legato on the same instrument, however,

KOTs varied only as a function of tone duration (tempo), possibly for kinematic

reasons unrelated to the decay characteristics of the tones. Thus, perception and

production were not perfectly matched. However, a tendency to assign longer KOTs

to relatively consonant than to dissonant successive tones was observed in both

perception and production. The production data also revealed a tendency of some

pianists to play more legato with the right than with the left hand and a highly

consistent pattern of variation in KOT as a function of position in the tone

sequence.

The present research used the same methods to investigate staccato

articulation, which apparently has not been the subject of any previous quantitative

studies. Staccato is not the same as non-legato, although the distinction vanishes

when the tempo is fast. Staccato articulation requires that successive tones be not

only separated by a gap but also short in duration; a sequence of long tones separated

by gaps does not sound staccato. A basic assumption underlying the present study

was that there is a perceptual category of staccato having the properties just stated. It

may be the case that notes marked as staccato in a score (by dots above the notes) are

sometimes executed in a way that is perceptually not staccato but rather non-legato.

This is especially likely with relatively long note values such as quarter notes or half

notes.

It was also assumed that for a given musical passage there is such a thing as a

typical or optimal staccato, in which the note durations are neither too long nor too

short. Of course, there are contextual, stylistic, expressive, and individual variations

in the degree of staccato in real music, and there is also a special notation for a very


sharp staccato (wedges above the notes). Within a given context, however, and

particularly in the stylistically and expressively neutral scales and arpeggi used here,

there may well be a typical or optimal staccato, at least for each individual pianist. It

might be asked why optimal staccato would not simply consist of the shortest

possible note durations. In a production task, however, mechanical and kinematic

constraints probably prevent the notes from getting shorter than a certain

minimum. Although such constraints do not operate in a perceptual adjustment

task, so that non-pianist participants might well select the shortest possible tone

duration as the optimal staccato, pianist participants were expected to rely on their

knowledge of typical staccato tone durations in performance and to refrain from

selecting minimal note durations. For this reason, skilled pianists were used as

participants in both perception and production tasks.

For convenience, the term “note duration” is used here to refer to the time

from key depression to key release.1 Two questions asked in the present study were

(1) what the typical duration of staccato notes might be in a neutral context, and (2)

whether that typical duration is constant or varies with tempo. When the tempo is

increased to a point where note inter-onset intervals (IOIs) are not much longer

than note durations, note duration would most likely have to covary with IOI

duration to prevent staccato from changing to non-legato or legato. At slower

tempi, however, where IOIs are substantially longer than the typical duration of

staccato notes, invariance of note duration seemed a theoretical possibility. It was

hypothesized, however, that the muscular relaxation and kinematic reorganization

brought about by a slowing of tempo might affect the criterion for an optimal

staccato, resulting in a relative lengthening of staccato notes at slower tempi in both

production and perception. This would be consistent with the finding in motor

control studies that the key contact time in rhythmic finger tapping increases as the


tapping rate is decreased (Billon & Semjen, 1995; Piek, Glencross, Barrett, & Love,

1993).

The effects of several additional variables on the duration of staccato notes

were investigated, in analogy to Repp’s previous studies of legato articulation. One

of these variables was pitch height or octave, referred to here as “register”. Since

higher piano tones decay more rapidly than lower tones, they may seem less loud

and/or subjectively shorter, and this may lead pianists to depress the key longer for

them to achieve an equal degree of staccato. (The highest piano keys, however, are

without dampers, so that the duration of the key depression does not affect the

acoustic tone duration.) Another independent variable was the degree of

consonance of the successive tones, defined in terms of their pitch separation (1, 2,

or 3 semitones). Since consonance is relevant primarily to the perceptual tolerance

of acoustic overlap, which is important in legato but minimal in staccato

articulation, this variable was not expected to have much of an effect on staccato

note durations.

In the perceptual adjustment tasks of the earlier legato studies, listeners were

asked to find the minimal and maximal as well as the optimallegato. In the present

study, only optimal staccato adjustments were requested, for rather obvious

reasons. Maximal staccato merely implies extremely short tone durations and

therefore is of little interest, unlike maximal legato, which defines an overlap

detection or overlap tolerance threshold. The boundary between minimal staccato

and non-legato (or rather non-staccato) is not well defined, unlike that between

minimal legato and non-legato, which represents a gap detection threshold. Instead

of varying the listeners’ perceptual criteria, then, it was decided to obtain several

replications of optimal staccato judgments.

In the staccato production task, two additional variables came into play. One

was the hand with which a tone sequence was played. Repp (1997) observed a


tendency for some pianists to play more legato with the right than with the left

hand. This makes sense because it is usually the right hand that plays the melodies

in which legato is important, and legato is a refined technique that requires much

practice. However, there was no similarly compelling reason to expect hand

differences in staccato playing. The other variable was the position of a tone within

the sequence or, alternatively, the finger with which a tone was played. In legato

playing, very consistent positional effects were observed that seemed to be related to

the melodic contour or metrical structure of the sequence. Here it was investigated

whether similar positional effects exist in staccato articulation.

One further variable of interest was the instrument used. The previous legato

studies compared perception and production, with different groups of participants

in the two tasks, on a digital piano (Repp, 1995) and on a real computer-controlled

piano, a Yamaha Disklavier (Repp, 1997). In the present perceptual task, only the

digital piano was used because the Disklavier was found to be too unreliable at the

very short tone durations required for the staccato adjustments. The production

experiment, however, was carried out on both instruments. Moreover, both tasks

were performed by the same pianists on the digital piano, and most of them played

on the Disklavier as well. This made possible a within-pianist comparison of

staccato perception and production, as well as of playing on two different

instruments. It was considered likely that the mechanical and acoustic properties of

an instrument would affect, respectively, the kinematics of staccato production and

the perceptual criterion for optimal staccato note duration.


PERCEPTION EXPERIMENT

Method

Participants. The participants were 7 pianists with advanced skills. Three of

them were graduate students of piano performance at the Yale School of Music, one

was an undergraduate studying there for a performance certificate, and three were

undergraduates at Yale University. They were paid for their participation.

Design. The stimuli were continuously ascending and descending 5-tone

sequences. There were 27 sequences resulting from the factorial combination of

three IOI durations, three pitch registers, and three pitch step sizes. The IOIs were

187, 375, and 750 ms. The registers were the second, fourth, and sixth octaves on the

piano. The step sizes were 1, 2, and 3 semitones (st). To keep the average pitch

constant within each register but at the same time make the keys lie comfortably

under the hand for the production study, all sequences were centered on G. The 1-st

(chromatic) sequence thus consisted of the notes F-F#-G-G#-A, the 2-st (whole-tone)

sequence of D#-F-G-A-B, and the 3-st (diminished-seventh arpeggio) sequence of

C#-E-G-A#-C#.

Procedure. A Roland RD-250s digital piano was controlled via a MIDI

interface by a MAX patcher running on a Macintosh Quadra 660AV computer.2 All

tones were played with “Piano 1” sound at a constant MIDI key velocity of 60. The

participant sat in front of the computer, listened to the sequences over Sennheiser

HD540 II earphones, and started and stopped sequences by clicking “buttons” in a

panel displayed on the monitor. Also displayed was a “slider” with a “handle” that

could be dragged with the mouse to vary note duration.3 The slider had a fixed

range from 10 to 160 ms. This range was based on the author’s judgments in pilot

runs, according to which note durations beyond 160 ms seemed definitely

unacceptable as staccato articulations. The slider was unlabeled and was


automatically reset to the left-most (10 ms) position at the beginning of each trial, so

that the tones in each sequence were extremely short initially. The participant’s task

was to start a sequence (which always began with the lowest tone), then move the

slider to the right and slowly back and forth until the tones in the sequence sounded

optimally staccato, then to stop the sequence and start the next one. The MAX

patcher presented the 27 sequences in random order and stored the participant’s

final slider settings. After some initial practice, each participant completed three

blocks of 27 trials in different random orders. Blocks were separated by short rests.

Analysis. Average note durations and standard deviations across blocks were

analyzed in separate repeated-measure ANOVAs with register (3), step size (3), and

IOI (3) as fixed variables, and pianists (7) as the random variable. ANOVAs on

pianists’ individual data were also conducted, with blocks (3) as the random

variable. Because of the many significance tests and the smaller error variance

within individuals, only effects with p < .01 were considered significant in the

individual analyses.

Results

The results are summarized in Figure 1 in terms of average note durations

and average within-pianist standard deviations, each with standard error bars

representing the variability among pianists. Average adjusted note durations fell

between about 20 and 80 ms, which suggests a stable perceptual criterion that was

not constrained by the upper limit of the MAX slider (160 ms). There were two

significant main effects in the ANOVA. First, there was the predicted increase of

adjusted note duration with increases in pitch register [F(2,12) = 14.1, p < .002]. The

increase occurred mainly between the low register and the two higher registers.

Second, note duration clearly increased with IOI duration [F(2,12) = 18.4, p < .001],

across all three values. The within-pianist standard deviation of the adjustments


likewise increased with IOI duration [F(2,12) = 13.9, p < .002]. Step size did not have

a significant effect, and there were no significant interactions.

-----------------------------

Insert Figure 1 here

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There were considerable individual differences among the seven pianists

with regard to the preferred absolute note durations and the sizes of the main effects

(see Fig. 3 below). Five pianists showed a significant effect of register and five one of

IOI. Two pianists showed a significant interaction between register and IOI, such that

effects of register were largest at the longest IOI, and effects of IOI were largest in the

high register. A trend in this direction can also be seen in Figure 1, though it was not

significant overall.

In summary, these results indicate that low tones are perceived as less staccato

than high tones having the same key depression duration. This could be due to

their slower pre- and post-release acoustic decay (Repp, 1995), which may make

them seem longer in duration than high tones. The results also suggest that

acoustically identical tones are perceived as less staccato when the tempo is

increased. This effect occurred at IOIs that were 6 to 24 times as long as the preferred

note durations and therefore cannot easily be attributed to a psychoacoustic

interaction between successive tones. More likely, a perceptual interaction between

rate and duration is involved which parallels a similar interaction in motor

kinematics (cf. Billon & Semjen, 1995; Piek et al., 1993).


PRODUCTION EXPERIMENT: DIGITAL PIANO

Method

Participants. The same pianists as in the perception study participated, during

the same experimental session.4

Procedure. The sequences were the same as in the perception study, but each

was restricted to three ascending-descending cycles and ended with a long note. The

sequences were notated in common meter on separate music sheets, and the three

IOI durations were represented by sixteenth, eighth, and quarter notes, respectively.

The sheets for the middle register were duplicated and marked “left hand” or “right

hand”, so that there were 36 sheets in all. The low-register sequences (notated in bass

clef) were to be played with the left hand only, and the high-register sequences with

the right hand only. The staccato articulation was not indicated in the notation but

was requested verbally. The music sheets were shuffled randomly for each pianist. A

metronome flashing silently at a rate of 80 per minute (IOI = 750 ms, understood to

correspond to quarter-note beats) was in view, and the “Piano 1” sound was audible

over Sennheiser HD540 II earphones. The pianists were instructed to play each

sequence at the prescribed tempo, but not necessarily in strict synchrony with the

metronome. The resulting IOIs were thus approximately the same as in the

perception study (i.e., 187, 375, and 750 ms). The fingering for each cycle was

prescribed to be 1-2-3-4-5-4-3-2 for the right hand and 5-4-3-2-1-2-3-4 for the left hand.

The performances were recorded by a MAX patcher, and the order of the sequences

was recorded by the experimenter. The last step was accidentally omitted for one

pianist, so that it could not be determined later which middle-register sequences had

been played with which hand. That pianist’s middle-register data were averaged

across the two hands and then duplicated to fill all cells of the design for the

ANOVAs. The note durations were calculated from the recorded MIDI data.


Analysis. An overall repeated-measures ANOVA was conducted on the note

durations averaged across the three cycles within each sequence, with IOI (3), step

size (3), register (2), hand (2), and position (8) as fixed variables, and pianists (7) as

the random variable. Register and hand were treated as 2-level orthogonal variables

in this analysis, even though hand was confounded with register: The register

variable contrasted low-left and mid-right with mid-left and high-right, whereas the

hand variable contrasted low-left and mid-left with mid-right and high-right. The

position variable represented the 8 notes in a cycle, which were played by different

fingers in the two hands. Subsequently, separate ANOVAs were conducted on the

left-hand and right-hand data, and on the mid-register data. Finally, separate

ANOVAs were conducted on each pianist’s individual data, with the same design as

the overall ANOVA but with cycles (3) as the random variable. Effects in the

individual ANOVAs had to be significant at p < .01 to be considered reliable. Even

so, due to the small error variances, numerous effects reached significance at the

individual level, so that they will be mentioned only where they are of special

interest. F values reported below are from the overall ANOVA, unless specified

otherwise.

Results

The effects of register, step size, and IOI are summarized in Figure 2, which

has the same format as Figure 1. However, the standard deviations here represent

the average within-pianist variabilities across the 8 positions in a sequence, after

averaging across the three cycles. (Variabilities across cycles were even smaller.) The

standard deviations did not show any systematic trends and were not analyzed

statistically.-----------------------------Insert Figure 2 here

-----------------------------


It can be seen right away in Figure 2 that the average produced note durations,

which ranged roughly from 80 to 170 ms, were substantially longer than the

perceptually adjusted ones (Fig. 1). Note duration clearly increased with IOI duration

[F(2,12) = 6.9, p < .02], although the significance level was not very high, due to large

individual differences in the magnitude of the IOI effect (see below). These

individual differences are evident in the large standard errors at the longest IOI

duration. By contrast, standard errors were very small at the shortest IOI duration,

indicating that the pianists played with similar note durations at this fast tempo. As

in the perceptual adjustment data, step size did not have a significant main effect.

Register did have a significant main effect [F(1,6) = 10.1, p < .02], but it was very

small (only 5 ms) and surprisingly indicated longer note durations in the lower

registers, contrary to the perceptual results. There were no significant effects of

register in the separate ANOVAs of the left- and right-hand data. The only

significant interaction among the three variables represented in Figure 2 was that

between IOI and step size [F(4,24) = 3.8, p < .02]. It was due to a somewhat reduced

lengthening of notes in 3-st sequences at the 750-ms IOI duration, compared to 1-

and 2-st sequences at that IOI. It was also significant in the left-hand data [F(4,24) =

3.4, p < .03], but not in the right-hand data.

The large individual differences in the magnitude of the IOI effect deserve

attention; the individual F(2,4) values ranged from 15.8 (p < .02) to 2959. To

determine whether these differences showed any relationship to individual

differences in the effect of IOI on the perceptual adjustments, Figure 3 plots the

results of the two tasks against each other, with the note durations at the three IOIs

being shown separately for each pianist. There was indeed a relationship, though

not a very strong one. Three pianists (M.A., D.G., T.C.) showed large effects of IOI in

both perception and production, and one (C.M.) moderate ones. Two pianists (P.C.,

H.S.), however, showed sizeable IOI effects only in perception, not in production.


The seventh pianist (P.W.) produced very short durations and showed only very

small effects of IOI in both tasks. Apparently, different pianists used different

kinematic strategies in staccato production.

-----------------------------


-----------------------------

There was no significant main effect of hand in the overall ANOVA. The

separate ANOVA on the mid-register data (omitting the pianist for whom no hand

information was available) likewise did not reveal any overall effect of hand.

Moreover, no individual pianist showed a significant hand difference, and hand did

not interact significantly with IOI, register, or step size.

More complex results were obtained for the remaining variable, position in

the sequence. Position had a significant main effect in the overall ANOVA [F(7,42) =

2.9, p < .02] and was also involved in four significant interactions: with step size

[F(14,84) = 3.3, p < .0005], with register and hand [F(7,42) = 7.0, p < .0001], with hand

and step size [F(14,84) = 2.6, p < .005], and with all three of these variables [F(14,84) =

2.8, p < .002]. The position main effect was significant for the left hand alone [F(7,42)

= 3.8, p < .004], but not for the right hand alone. It reached significance in the

separate mid-register ANOVA [F(7,42) = 2.7, p < .03], but its interaction with hand

fell short of significance. Each of these subsidiary ANOVAs also showed significant

interactions involving position. For the left hand alone, position interacted with

register [F(7,42) = 3.4, p < .006], with register and step size [F(14,84) = 2.2, p < .02], and

with register and IOI [F(14,84) = 2.0, p < .04]. For the right hand alone, it interacted

with register [F(7,42) = 6.2, p < .0001] and with step size [F(14,42) = 4.9, p < .0001]. In

the mid register, it interacted with step size [F(14,42) = 2.4, p < .008] and with hand

and step size [F(14,42) = 2.1, p < .03]. In summary, there was significant positional


variation in note duration, and this variation depended on hand, register, and step

size, but not on IOI.

Accordingly, Figure 4 shows the results separately for the two hands, broken

down according to register and step size.5 Error bars are omitted for clarity. The

results are not easy to interpret. There are three factors that, hypothetically, could

have played a role. One is metrical structure. This hypothesis predicts a main effect

of position, with longer note durations in the metrically strong first and fifth

positions.6 The first note was indeed lengthened in some conditions, but by no

means in all; and there was little evidence for lengthening in the fifth position. The

second factor is finger. This hypothesis predicts a position by hand interaction, such

that note durations in the second, third, and fourth positions are similar to those in

the eighth, seventh, and sixth position of the same hand, and also to those in the

sixth, seventh, and eighth positions of the other hand (see the abscissa labels of Fig.

4). The data lend some support to this hypothesis within hands (mainly within

conditions), but not between hands. The third possible factor is black versus white

keys. This hypothesis predicts an interaction between position and step size. The

black keys were in positions 2, 4, 6, and 8 in the 1-st sequence, in position 1 only in

the 2-st sequence, and in positions 1, 4, 5, and 6 in the 3-st sequence. No related

patterns are evident in Figure 4. None of these three hypotheses predicts the

observed interaction of position with register. Some similarities between the mid-

register patterns for the two hands should be noted: Longer notes played with the

third finger in 1-st sequences, shorter notes played with the fourth finger in 2-st

sequences. However, the pattern of positional variation remains largely

unexplained.

-----------------------------


-----------------------------


In summary, the main results of this experiment are that produced staccato

note durations are longer than perceptually adjusted ones, and that they increase as

the tempo decreases. The first result suggests a lower limit to produced staccato note

durations, perhaps specific to the mechanical properties of the instrument. In other

words, the pianists may have wanted to produce shorter note durations but

somehow were not able to, either because they could not move their hands/fingers

fast enough or because the digital piano keys did not bounce back quickly enough.

The effect of tempo suggests a small, obligatory effect on hand/finger kinematics,

perhaps due to general muscular tension/relaxation, plus a much larger effect for

some pianists that presumably was under conscious control and may reflect

common performance practice. In other words, these pianists played non-legato

rather than staccato at slower tempi, as may be common when there are dots above

longer note values in printed music.

PRODUCTION EXPERIMENT: REAL PIANO

Method

Participants. Ten pianists participated in a separate experimental session that

preceded the digital piano session and during which also the legato productions

reported in Repp (1997) were recorded. Six of the participants were the same as in

the digital piano session. The additional four participants were one graduate student

of piano performance, two undergraduate pianists, and the author.

Procedure and analysis. The procedure was exactly the same as with the

digital piano. The instrument was a Yamaha Disklavier grand piano. Due to an

unfortunate oversight, the order of the sequences was not recorded for five pianists,

so that hand information was unavailable for them. Their middle-register data were

averaged across the two hands and then duplicated to fill the cells of the overall


design. Their data were omitted in the separate ANOVA on the mid-register

condition.

Results

The effects of register, step size, and IOI are summarized in Figure 5. It is

evident that the average note durations, ranging from about 40 to 120 ms, were

much shorter than on the digital piano (Fig. 2), though still not as short as the

perceptual adjustments (Fig. 1). Otherwise, their pattern was rather similar to the

digital piano data. Again, there was a clear increase in note durations with IOI

duration [F(2,18) = 6.1, p < .01], but the relatively low significance level and the large

standard errors at the longer IOIs again indicate pronounced individual differences.

There was no significant effect of step size. Register had a marginally significant

main effect [F(2,18) = 6.1, p < .04], again indicating slighly longer note durations in

the lower registers. There were no significant interactions among these three factors.

-----------------------------


-----------------------------

The main effect of IOI fell short of significance for two pianists, neither of

whom participated in the digital piano session. Figure 6 compares the note

durations on the digital (Roland) and real (Yamaha) pianos at the three IOIs for the

six pianists who participated in both sessions. There was considerable agreement.

Two pianists (T.C., D.G.) showed similarly large effects of IOI on both instruments,

two (M.A., C.M.) showed smaller effects on the Yamaha than on the Roland, and

two (P.W., P.C.) showed very small effects on both.

-----------------------------


-----------------------------


Unexpectedly, there was a significant main effect of hand in the overall

analysis [F(1,9) = 14.8, p < .004], indicating slightly longer note durations in the left

than in the right hand (an average difference of 8 ms). The effect was also significant

in the ANOVA on the mid-register data of the five pianists for whom hand

information was available [F(1,4) = 11.3, p < .03]. However, it reached significance

for only two of these five pianists individually. Hand did not interact with IOI,

register, or step size, except for a weak quadruple interaction that may be

disregarded.

Again, more complex but reliable results were obtained for position. The

main effect of position was highly significant [F(7,63) = 8.8, p < .0001], and it

interacted strongly with register and hand [F(7,63) = 10.2, p < .0001] and with register,

hand, and step size [F(14,126) = 3.2, p < .0004], and weakly with register and step size

[F(14,126) = 1.8, p < .05] and with hand and IOI [F(14,126) = 2.2, p < .02]. In the left-

hand data, it interacted mainly with register [F(7,63) = 3.9, p < .002], though there

were three other weak interactions. In the right-hand data, it interacted strongly

with register [F(7,63) = 7.1, p < .0001], with register and step size [F(14,126) = 3.2, p <

.0003], and weakly with IOI. In the mid-register data (for 5 pianists only), only the

main effect reached significance. So, it was again mainly the three variables of hand,

register, and step size that affected positional differences.

The patterns of note durations are shown in Figure 7, which is analogous to

Figure 4 for the Roland data. The data are more systematic here in that they show

lengthenings in the first and fifth positions in nearly all conditions. This supports a

metrical interpretation. The finger hypothesis is less clearly supported, and there

seems to be no support at all for the black key hypothesis. The data for the two hands

show some considerable similarities, even between the low and high registers. The

right hand played shorter note durations in the high than in the mid register,


especially at the end of each cycle, which may account for some of the interactions in

the ANOVA.

In summary, these results largely replicate those for the digital piano. The

shorter note durations presumably reflect the mechanical properties of the real

piano, whose keys offered greater resistance and therefore bounced back more

quickly. However, they evidently still imposed a lower limit to the duration of

staccato notes.

GENERAL DISCUSSION

The results of the adjustment task support the assumption that pianists, at

least, have a perceptual category of staccato according to which a certain range of

note durations is considered optimal. On the digital piano, that range was from 20 to

80 ms. Of course, this finding may be of limited generality. First, there were

considerable individual differences and also considerable variability within

individuals. Second, the results were obtained on a specific instrument whose

sounds were heard over earphones. Although the digital piano tones resembled

natural piano tones, their post-release decay times were relatively short (Repp, 1995,

1997), which means they simulated a relatively nonreverberant environment. Note,

however, that this should have biased participants to choose longer note durations,

not shorter ones. Third, the adjusted note durations increased strongly with IOI, and

it seems possible that even longer note durations might have been chosen, had

even slower tempi been included. Thus the perceptual category of staccato is highly

flexible and context sensitive, as is staccato production.

There were several striking discrepancies between the perceptual adjustments

and the played note durations. The latter were much longer than the former,

especially on the Roland digital piano, but also on the Yamaha Disklavier. The note


durations at the fastest tempo, which varied little between pianists, probably

represent a lower limit due to the mechanical properties of the instrument. On the

Roland, this lower limit was about 80 ms, whereas on the Yamaha it was 40–50 ms,

on the average. (Some individual pianists achieved shorter durations.) This

difference between instruments most likely reflects the lower resistance and weaker

resilience of the digital piano keys as compared to the real piano keys. These results

suggest that the duration of short staccato notes may depend critically on the piano

action, even within the range of real pianos. In theory, the difference could also be

due to the faster post-release decay of the digital piano tones (see Repp, 1995, 1997),

for which pianists may have compensated by holding the keys down longer, but this

psychoacoustic explanation would not account for the different criteria in perception

and production of the digital piano tones.

At the slower tempi in production, large individual differences came into

play. While some pianists changed their produced note durations relatively little as

IOIs increased, others showed dramatic increases that went way beyond the

acceptable range for staccato suggested by the perceptual adjustment data. Thus these

tones presumably would not be perceived as staccato, even though they were

intended as staccato. This apparent paradox probably reflects a discrepancy between

perception and performance practice. It may have been caused by the musical

notation that was used to elicit the productions, specifically by the fact that IOI

durations were coded as different note values. Staccato articulations of long note

values may be perceptually non-legato (or rather, non-staccato). An alternative way

of notating the music would have been to keep the note values constant (sixteenth

notes) and to code IOI durations in terms of following rests. In that case, less of an

increase in note duration with IOI duration might have been observed.

To the extent that a small increase in note duration with IOI is obligatory or at

least natural, it may be attributed to the kinematics of executing cyclical wrist


movements at different tempi (Billon & Semjen, 1995; Piek et al., 1993). It seems

reasonable that a slow tempo relaxes somewhat the rapid and tense downward

movement that is required to produce a staccato tone. It is less easy to explain the

increase in perceptually adjusted note durations with IOI. There is no obvious

psychoacoustic reason why short tones spaced further apart should sound

subjectively shorter than tones that occur in close succession. Yet, this is what the

perceptual data suggest. In the absence of a psychoacoustic explanation, it can only be

speculated that staccato tones sound subjectively shorter at a slow tempo because

they tend to be played longer at such a tempo. In other words, the finding may

represent a perceptual-motor interaction (cf. Viviani & Stucchi, 1992a, 1992b).

Another difference between perception and production concerned the effect

of register. Perceptually adjusted note durations were clearly shorter in the low

register than in the mid and high registers. This may be explained by the slower pre-

and post-release decay of low tones, which is likely to increase their subjective

duration and perhaps also their loudness. In staccato playing on either instrument,

however, there was no such effect of register; in fact, there was a slight trend in the

opposite direction. This implies that notes played in the low register would be

perceived as less staccato than those in higher registers. It appears that the pianists

maintained a similar kinematic regime in different registers, regardless of the

perceptual result.

There were no hand differences in performance on the digital piano. On the

Disklavier, however, several pianists played staccato notes somewhat longer with

the left than with the right hand. This may be due to a relative weakness of the left

hand in these pianists and thus is not of great theoretical interest.

Effects of sequential position in production were complex, especially on the

digital piano, and only partially explainable by fingering. On the Disklavier, notes in

metrically strong positions tended to be held longer. Additional data not reported


here (performance of a short piece by Schumann) suggest that staccato articulation is

less variable than legato articulation as a function of musical factors. This is not

surprising because staccato is essentially a more primitive form of articulation than

legato, requiring only a relatively stereotyped movement and bringing to the fore

the percussive nature of the piano, whereas legato attempts to overcome this

mundane aspect by simulating the singing voice, however imperfectly.


ACKNOWLEDGMENTS

This research was supported by NIH Grant MH-51230. It would not have been

accomplished without the assiduous assistance of Lisa Robinson and Paul Buechler.

Address correspondence to Bruno H. Repp, Haskins Laboratories, 270 Crown Street,

New Haven, CT 065112-6695. Electronic mail: [email protected]. Internet:

http://www.haskins.yale.edu/haskins/STAFF/repp.html.


FOOTNOTES

1“Note duration” is MIDI jargon for the time between “note on” (i.e., key

depression) and “note off” (i.e., key release) commands. It is to be distinguished

from acoustic tone duration, which is longer than note duration due to post-release

decay of acoustic vibrations, from auditory (subjective) tone duration, which is a

perceptual magnitude, and from note value, which is a symbol in a score and has no

duration at all.

2 A MAX patcher is a program written in MAX, which is a graphic

programming language for MIDI applications. One peculiarity of MAX is that the

tempo of the MIDI output and input does not correspond exactly to the time values

specified in and recorded by the program. With the exception of the IOI durations of

the stimuli, which were specified in MAX so as to yield the real-time values stated

(187, 325, and 750 ms), all data (perceptual adjustments and production durations)

will be reported in uncorrected form, as they appeared inside MAX. The real-time

values were uniformly longer by about 4%, as determined by control measurements.

(This was with a setup in which the OMS software was disabled.)

3The decay characteristics of the digital piano tones are described in Repp

(1995). It should be noted that strings above F#6 do not have dampers on a real

piano, and this was simulated on the digital piano as well, so that varying note

duration had no effect on the sound of the upper three notes of the high-register

sequences.

4Due to a long delay between data collection and analysis, the order of the

perception and production tasks could no longer be determined with certainty.


However, the author believes that the production task always preceded the

perception task.

5The data of the pianist whose mid-register data were averaged across left and

right hands are included here.

6An interaction of meter with IOI might also be predicted, due to changes in

metrical structure with tempo, but no such interaction was evident in the statistical

analyses.


REFERENCES

Billon, M., & Semjen, A. (1995). The timing effects of accent production in

synchronization and continuation tasks performed by musicians and

nonmusicians. Psychological Research, 58, 206–217.

Kuwano, S., Namba, S., Yamasaki, T., and Nishiyama, K. (1994). Impression of

smoothness of a sound stream in relation to legato in musical performance.

Perception & Psychophysics, 56, 173–182.

Martin, D. W. (1947). Decay rates of piano tones. Journal of the Acoustical Society of

America , 19, 535–541.

Piek, J. P., Glencross, D. J., Barrett, N. C., & Love, G. L. (1993). The effect of temporal

and force changes on the patterning of sequential movements. Psychological

Research, 55, 116–123.

Repp, B. H. (1995). Acoustics, perception, and production of legato articulation on a

digital piano. Journal of the Acoustical Society of America, 97, 3862–3874.

Repp, B. H. (1997). Acoustics, perception, and production of legato articulation on a

computer-controlled grand piano. Journal of the Acoustical Society of

America , 102, 1878-1890.

Viviani, P., & Stucchi, N. (1992a). Biological movements look uniform: Evidence of

motor-perceptual interactions. Journal of Experimental Psychology: Human

Perception and Performance, 18, 603–623.

Viviani, P., & Stucchi, N. (1992b). Motor-perceptual interactions. In G. E. Stelmach &

J. Requin (eds.), Tutorials in motor behavior II (pp. 229–248). Amsterdam:

Elsevier.


FIGURE CAPTIONS

Fig. 1. Results of perceptual adjustment experiment: Average note duration

and within-pianist standard deviation as a function of IOI, step size, and register,

with standard error bars.

Fig. 2. Results of production experiment on the Roland digital piano: Average

note duration and within-pianist standard deviation (across sequential note

positions) as a function of IOI, step size, and register, with standard error bars.

Fig. 3. Perceptually adjusted note durations plotted against note durations

played on the Roland digital piano, separately for 7 pianists, as a function of IOI

(increasing from lower left to upper right).

Fig. 4. Average note durations on the Roland digital piano as a function of

sequential position, register, and step size, separately for (a) the left hand and (b) the

right hand.

Fig. 5. Results of production experiment on the Yamaha Disklavier: Average

note duration and within-pianist standard deviation (across sequential note

positions) as a function of IOI, step size, and register, with standard error bars.

Fig. 6. Note durations played on the Roland digital piano plotted against note

durations played on the Yamaha Disklavier, separately for 6 pianists, as a function of

IOI (increasing from lower left to upper right).

Fig. 7. Average note durations on the Yamaha Disklavier as a function of

sequential position, register, and step size, separately for (a) the left hand and (b) the

right hand.


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Documents

Perception and Production of Staccato - Haskins … and Production of Staccato Articulation on the Piano Bruno H. Repp ... legato is indeed characterized by a small overlap in key