Research regarding the positions of
4 supports for the baseplate of aspeaker stand and the effect of
reducing the noise of themounted speaker
Hideki Yabuuchi, Graduate School ofSystems Engineering, Kinki University
Kiminobu Nishimura, Department of Mechanical Engineering,
Faculty of Engineering, Kinki University

1. Background of Research
It is known that when music is played with audio
equipment, sound quality degrades because ofnoise produced by various factors.
It is common to use audio accessories in orderto improve the sound quality of audio
equipment. These definitely change sound, but it
is unclear whether it means improvement.
In this research, the authors focused on aspeaker stand, and experimentally discussed theeffects of the positions of the supports for its
baseplate on the mounted device.

Copyright © 2015 Kinki University Faculty of Engineering & KRYNA Inc.

2. Purpose of Research
The purpose of this research is:
Effects of reducing the noise and vibrationon the mounted speaker

Top plate
ColumnBaseplate

The effect of improving sound quality
based on a listening experiment.

Spike

ColumnBaseplate

4 angular pointsfor supporting

4 middle pointsfor supporting

Copyright © 2015 Kinki University Faculty of Engineering & KRYNA Inc.

3. Experiment method
The authors discussed each supporting method effects of reducing the vibration and noise on themounted speaker.
The authors made the speaker generate radiating sound, and studied the effects on the baffle
surface, the unit part, and the radiating sound.
SoundRadiation

White noise
Vibrational characteristics of thebaffle surface
Sine-wave signal
Vibrational characteristics of theunit part Effects on radiating
sound (harmonic components)

MicAV Amplifier
CD Player

Laser Doppler
vibration
galvanometer
PSV-400

Vibrationbalvanometer
control
OFV-5000

FFT
Analyzer
DS-2000
PC

Copyright © 2015 Kinki University Faculty of Engineering & KRYNA Inc.

4. Experiment Results and Discussion
Vibrational characteristics of the baffle surface

4.1 White noise
The vibration range shrank in the enclosure
part surrounding the unit.
It can be considered that vibration wassuppressed in the case of supporting at 4
middle points.
Vibrational characteristics of the unit part4.2 Sine-wave signal (unit part)
The vibrational distribution at the woofer
part became nearly concentric.
It can be considered that the distortion ofthe woofer part decreased.
supporting at
4 angular points

supporting at
4 middle points

Copyright © 2015 Kinki University Faculty of Engineering & KRYNA Inc.

4.3 Effects on radiating soundHarmonic components mean the noise generated by resonance.
As harmonic components decrease, vibration is dampened more.
<Harmonic component damping amount for each supporting method>
Supporting at 4 angular points

Supporting at 4 middle points

Frequency[Hz]Sound pressure level [dB]

Difference [dB]

Sound pressure level [dB]

Difference [dB]

Improvement [dB]1000

-56.30----56.43---0.132000-99.0542.74-98.95

42.52

0.22

3000

-104.1347.83-104.97

48.55

-0.71

4000

-121.4565.15-120.55

64.12

1.03

5000

-114.1957.89-113.05

56.62

1.27

6000

-130.0773.77-130.86

74.43

-0.67

7000

-128.0771.77-130.86

74.43

-2.66

8000

-138.72

82.41-142.67

86.25

-3.83

9000

-138.95

82.65-140.71

84.28

-1.63

In the case of supporting at 4 middle points, third-order, sixth-order, andhigher-order harmonic components decreased considerably.
This is considered because the distortion of the unit part eased.
Copyright © 2015 Kinki University Faculty of Engineering & KRYNA Inc.

5. Listening Experiment
In order to study how the above mentioned experiment results influence sound quality,
we conducted a listening experiment and discussed the effect of improving sound quality.

Comments such as"Sound quality is good" and "This is good sound"
Vary among people, and strongly Depend on their preference.

We carried out 2 kinds of experiments:
1. an auditory lateralization experiment
2. a sound quality evaluation experiment.

Copyright © 2015 Kinki University Faculty of Engineering & KRYNA Inc.

5.1 Auditory lateralization experiment
Auditory lateralization means the ability to grasp the direction and distance to a sound source.
When sound quality improves,(1) the range and (2) phase of the audio image become clear.

Improvement insound quality

Copyright © 2015 Kinki University Faculty of Engineering & KRYNA Inc.

5.2 Experiment results (auditory lateralization)
Subjects drew the audio image of each sound source, and the variations in area and coordinates
were summarized as data.
The right and left senses of auditory lateralization became clear.
The audio image of the piano became clear, while other audio images became vague.
The possible reason for the vagueness is that sound reverberation increased and it was sensed as anaudio image.

SPSPVocal
9.48cm+31.81%

Evaluation of theaudio image of the vocal part

SPSPSPSP

GuitarPiano

23.15cm+2.25%

7.46cm-17.28%

Evaluation of theaudio image of the guitar

Evaluation of theaudio image of the piano
Copyright © 2015 Kinki University Faculty of Engineering & KRYNA Inc.

5.3 Sound quality evaluation experiment
We set 9 items: depth, extent, height, resolution, lightness, sense of sound distortion,sense of quietness, bandwidth, and timbre.
Five-grade evaluation was conducted, while giving Grade 3 to the method of supportingat 4 angular points.
DepthTimbre

Extent

5.4 Results of the sound quality
evaluation experiment
Bandwidth

HeightAll items improved.
Especially, extent, resolution, andbandwidth improved considerably.

Sense ofquietness

Resolution

Sense ofsound distortion
Supporting at
4 angular points

Lightness
Supporting at
4 middle points

Copyright © 2015 Kinki University Faculty of Engineering & KRYNA Inc.

6. Conclusion
It was confirmed that the method of supporting at 4 middle points has the effect of damping
vibration at both the unit and enclosure parts.
The effect of damping vibration and the reduction amount of harmonic components were larger inthe case of supporting at 4 middle points.
The right and left senses of lateralization became clear through the auditory lateralization
experiment.
In the sound quality evaluation experiment, all items improved. Especially, the effects on extent,

Copyright © 2015 Kinki University Faculty of Engineering & KRYNA Inc.

http://www.hiro.kindai.ac.jp/en/

KRYNA Inc.
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Acoustical Society of Japan
http://www.asj.gr.jp/Copyright © 2015 Kinki University Faculty of Engineering & KRYNA Inc.