Internationalof Computational
Intelligence
Systems
Journal ofJournal
Robotics,
Networking andArtificial Life
Vol.
XX(Z);
Month(2018),(Year), pp.
pp. 208–211
xx–yy
Vol.
5(3);
December
DOI:
10.1080/XXXXXXXXXXXXXX;ISSN XXXX–XXXX
onlineDOI:
10.2991/jrnal.2018.5.3.14;
ISSN 2405-9021
print; 2352-6386
onlinehttps://www.atlantis-press.com/journals/ijndc
https://www.atlantis-press.com/journals/jrnal

Research Article

Comparison of Off-line Visual and Verbal Feedback Instructions
for Keeping Tempo in Music
Hideyuki Tanaka1,*, Keita Ueda2
Graduate School of Education, Hiroshima University, Higashi-hiroshima, Hiroshima 739-8524, Japan
Department of Education, Hiroshima University, Higashi-hiroshima, Hiroshima 739-8524, Japan

12ARTICLE INFO
Article History
Received 18 May 2018
Accepted 14 November 2018
Key words

ABSTRACT
Ability of keeping the tempo is one of the important factors in playing music. In this paper, the authors carry out comparative
experiments on the effects of off-line visual and verbal feedback instructions for informing the performance in trying to keep thetempo at 1 Hz by tapping the rhythm. The participants are divided into experienced and non-experienced groups. The results
show that visual feedback may give too much information to experts of music and that experts can adjust the tempo by just using
the verbal feedback.

Rhythm in music
ability of keeping steady tempo
visual feedback
verbal feedback© 2018 The Authors. Published by Atlantis Press SARL.
This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).

1. INTRODUCTION
In music, rhythm is one of the important factors, and keeping thesteady tempo is the basis for playing music. Rhythm is the component of music that punctuates time, carrying us from one beat tothe next and subdivides into simple ration just like pitch [1].
In the classical method of teaching music, the teacher gives instructions and feedback on the performance of the student, commonly
providing the student with feedback using imagery, for example,“sing as if through the top of your head” [2]. The effects of feedback
instructions in music have been thus investigated by recording theprocess of teaching (e.g., Janice and Killian [3], Yarbrough et al.
[4]). Comparison of the different feedback instructions in dance
was carried out recently [5], but there are few comparison studies
in music within last 3 years.
On-line visual feedback has been investigated for music instructions. It was reported by Sadakata et al. [6] that abstract shapes areuseful for conveying on-line feedback information of timing andloudness; see also e.g., Hoppe et al. [2] for researches of on-line
visual feedback for music instructions.
Off-line feedback has been used in the traditional education ofmusic and it will be also used in future. It would be hence worthinvestigating, though on-line feedback is effective because of notime lag between the student’s performance and teacher’s feedback[2]. As far as the authors’ knowledge, effects of off-line visual andverbal feedback instructions have not been compared and investigated in the literature. We therefore carry out experiments for comparing the effects of off-line visual and verbal feedback instructions
in trying to keep the tempo constant at 1 Hz.
* Corresponding author. Email: tanakalpha@hiroshima-u.ac.jp

Chen et al. [7] reported that the variability of synchronization withvisual or verbal feedback depends on the frequency. Effects of practice on variability in an isochronous serial interval production task
was studied by Madison et al. [8], but not focusing on comparing
feedback instructions.

2. EXPERIMENTAL SETUP AND FEEDBACK
2.1. Experimental Setup
We show a schematic picture of the experimental setup inFigure 1. The participants beat the rhythm, holding a stick by
their dominant hand and tapping the dram pad. The microphone captures the sound of the beat and sends the signals tothe laptop PC of the windows OS. The PC analyzes the signals,obtains the time of the impacts by removing reverberation, andprovides information for visual and verbal feedback. In an offline setup, visual or the verbal feedback is given by the display
or by the language.
We assign the speed of the beat as 60 beats/min (1 Hz), and theparticipants try to keep the designated tempo in 2 min. Before
the experiments, we ask the participants to maintain the tempo as
close to the designated one as possible. We carry out experiments of
10 trials for each participant and give visual or verbal feedback after
each trial in an off-line setting.

2.2. Feedback for Informing Performance
Figure 2 shows a graph used for visually informing the periods
between impacts. We inform participants how to read the graph,

H. Tanaka and K. Ueda / Journal of Robotics, Networking and Artificial Life 5(3) 208–211

209

The average periods of the first and second half are respectively
given byN

Mp =1 p1 Ny (k ), M f =åå y(k),N p k =1
N f k = N p +1	 

and the difference between them by Mc = |Mp – Mf | and Md = Mp–Mf . We also compute the mean m and the variance s 2 of y(k).
Figure 1 | A schematic picture of the experimental setup

We give verbal feedback to the participants for the first and second
half as follows:· Good in the first (or second) half: Tapping the rhythm in thedesignated tempo, if Hp < 0.15 and Pp < 0.1 hold (or if Hf < 0.15and Pf < 0.1 hold).
· Fairly good in the first (or second) half: Tapping the steadyrhythm in the designated tempo but not keeping it in the designated tempo, if Hp < 0.15 only holds (or if Hf < 0.15 onlyholds).
· Not good in the first (or second) half: Tapping the rhythm
not in the designated tempo, if Hp > 0.15 holds (or if Hf > 0.15holds).

Figure 2 | The graph showing the tempo and time. The horizontal andvertical axes respectively express time and the periods between impacts.
The red line shows the result of the performance, where black crosses are
estimated from interpolation because of missing data. The constant line isthe designated period; if all the periods are closer to the designated one, it
indicates that the participant taps the rhythm better

Concerning the average speeds for the first and second half, wemoreover give the following feedback:and they can hence visually understand how she/he tapped therhythm in the trial.

· Fast in the first (or second) half: The beat is faster than thedesignated tempo, if Mp < 0.95 holds (or if Mf < 0.95 holds).

We give verbal feedback based on numerical values calculated by
the laptop computer. To this end, we define evaluation criteria forgiving judges of the tendency. Dividing the time interval of theexperiment into the first and second half, we analyze whether she/he keeps the tempo and taps the rhythm in the designated speed.

Comparing the speeds of the first and second half, we further givethe following feedback:For giving verbal feedback, we moreover calculate average temposof the first and second half and compute the difference between
them. The evaluation criteria are as follows: Let y(k) be the k-thperiod, where k = 1, 2, 3,…, N. The number Np of the first half data
is given by Np = N/2 or Np = (N + 1)/2 respectively for N even orodd, and the number Nf of the second half is Nf = N - Np. To judge
whether the rhythm is kept steady, we define the following criteria
respectively for the first and second half:
H p = max (|e(k)|) -	  k =1, 2 ,, N p

Hf =min (|e(k)|) ,k =1, 2 ,, N p

max (|e(k )|) -k = N p +1,, Nmin (|e(k)|) ,k = N p +1,, N

where e(k) is the error between the designated period r and the k-thperiod y(k):e(k) = r - y(k).	 
The sums of squares of the errors for the first and second half arerespectively defined as follows:
NpPp = å(e(k))2 , Pf =	 k =1N

å (e(k)) .

k = N p +1

2



· Slow in the first (or second) half: The beat is slower than thedesignated tempo, if Mp > 1.05 holds (or if Mf > 1.05 holds).

· Getting slower: The tempo of the second half is slower thanthe first one, if Md < 0 and Mc > 0.05.
· Getting faster: The tempo of the second half is slower than thefirst one, if Md > 0 and Mc > 0.05.

2.3. Experiments
The number of participants is 45, including 27 persons who haveenough experiences of playing music and 18 persons who have not.
We divide them into experienced and non-experienced groups, byasking them whether they have experiences of playing the instruments besides learning at class rooms in elementary, junior highor high schools. We also divide them into three groups of giving
visual feedback (nine from 27 experienced and six from 18 non-experienced, verbal feedback (nine from 27 experienced, six fromnon-experienced), and no feedback (nine from 27 experienced, sixfrom 18 non-experienced).
The participants first listen to the signal of 60 beats/min for thereference, where they can choose just listening to the signal or
beating the drum pad according to the signal. They then try tomaintain the tempo in 120 s. After the trial, we give visual orverbal feedback to the participants in the groups of under feedback. We carry out 10 trials and give them 5 min of rests after
the 4th and 7th trials, by taking physical and mental fatigues ofparticipants into account.

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H. Tanaka and K. Ueda / Journal of Robotics, Networking and Artificial Life 5(3) 208–211

3. RESULTS OF EXPERIMENTS
We first compare the results of experienced and non-experienced
participants of tapping the rhythm, focusing on the evaluation
values Pp and Pf . As we expected, the errors e(k) of experienced
participants is smaller than those of non-experienced participantsin all the groups of visual, verbal and no feedback. We thus do notshow the figure here.
We next compare the effects of visual, verbal, and no feedback.
Figures 3 and 4 show the sums of squares Pp and Pf of the error e(k)respectively for experienced and non-experienced participants.
Both of the figures show that the participants under visual or verbal
feedback (F.B.) can maintain the error smaller than those under nofeedback. Figure 3 indicates that verbal feedback is more effective
than visual feedback for the experienced participants.
We further compare the effects of visual, verbal, and no feedbackby using the variance s  2. Figures 5 and 6 show s  2 of experts andnon-experts, respectively. We see from Figures 3 and 5 that experienced participants can suppress the sums of squares of the error
e(k) by using visual feedback, but not the variance s  2. The result
implies that they can recognize the error in average (in the senseof the sum of squares) and that they can accelerate or decelerate bylooking at the graph, if they beat slow or fast respectively. However,by looking at the graph, they cannot properly control the varianceof periods. On the other hand, verbal feedback, often used forinstruction in music plays, gives better results than the visual one,as shown in Figures 3 and 5.
Regarding the variance, we have also obtained information
through questionnaire, by asking how they thought of feedback
between trials; they answered: “To achieve better performance,
I don’t worry about the details.”, “I tapped the rhythm without
thinking too much.”, and “I just cared the intervals of the reference signals between trials.” It seems that several experienced

Figure 5 | Variances s  2 of experienced participants

Figure 6 | Variances s  2 of non-experienced participants

participants thus considered that tapping the rhythm without
being influenced too much by the instruction of the graph leads
to better performances.
Summarizing the above results, visual feedback by the graphpossibly provided too much information for the experienced participants to maintain the variance of the rhythm,
whereas verbal feedback did appropriate information to them.
Experienced participants would thus confused by the difference
between their own feeling of rhythm and feedback indicated bythe graph, since bodily process, rhythm, and physical motion isthe basis of musical expressivity (Émile Jaques-Dalcroze [9]),and since bodily process and physical motion depend on theirown bodies.

4. CONCLUSION

Figure 3 | The sums of squares Pp and Pf of the errors for experienced
participants

We have carried out experiments of training for keeping the steady
tempo in music. We compared the effects of visual and verbal feedback for informing and improving their performance. The results
indicated that visual feedback by the graph seems to give too muchinformation to the experienced participants, and it may disturb
the expert participants in maintaining the steady tempo, because
they have their own feeling of rhythms. It is hence desirable for theteacher to send acceptable feedback to the student from the viewpoint of music education. Results may be improved by visual feedback, if we simplify the graph.

REFERENCES

Figure 4 | The sums of squares Pp and Pf of the errors for non-experienced
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H. Tanaka and K. Ueda / Journal of Robotics, Networking and Artificial Life 5(3) 208–211[3] J.K.N. Killian, Effect of instructions and feed-back on musicteaching skills, J. Music Ther. 18 (1981), 166–180.
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Authors Introduction
Mr. Hideyuki Tanaka

Mr. Keita Ueda
He graduated master course atGraduate School of Engineeringin Kyoto University and received
Dr. (Eng.) from Kyoto University.
He is now a member of Graduate
School of Education in Hiroshima
University. He is a member of IEEE,
SICE, and ISCIE.

He graduated Course of Technology
and Information Education in Schoolof Education in Hiroshima University.