Physiological Metronome

1
Physiological Metronome

• Adam Pala, Ben Fleming, Cole Drifka, Jeff Theisen

Clients Dr. Bill Fahl, Dept. of
Oncology Vanessa Young, Carnegie Mellon music
student Advisor Dr. Paul Thompson, Dept. of
Biomedical Engineering
2
Background

• Metronomes provide time or rhythm to musicians
• Currently metronome features include
• LCD display
• Mechanical and electronic timing mechanisms
• Beats which are audible and/or tactile
• Analog and digital user outputs

3
Design Motivation

• The motivation for our design comes from Vanessa
  Young, a music student at Carnegie Mellon
• Conventional visual and audio metronomes tend to
  be distracting
• Currently there is no adequate device on the
  market which functions as a metronome and uses a
  precise tactile pulse as the stimulus
• Such a metronome would allow the user to
  internalize the beat of the music

4
Client Requirements and Design Constraints

• The client requires the following for the
  metronome device
• Maintain the tempo in an inaudible and accurate
  manner
• Cover a tempo range of 40 to 260 bpm (beats per
  minute)
• Should not attach to parts of the body involved
  in playing the instrument (i.e. forearm or wrist)

5
Constant/Permanent Features of the Design

• The circuit (with slight modifications)

Original http//electroschematics.com/216/electro
nic-metronome-circuit-schematic/
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Constant/Permanent Features of the Design

• The case

http//www.hammondmfg.com/pdf/1593P.pdf
7
Design Aspect What is the form of tactile
stimulus?

• Options
• Vibration
• Compression
• Shock
• Tap

8
Option Vibration

• One option for the tactile stimulus would be a
  vibration, similar to that felt on a phone
• Vibration would be produced by an electric motor
• Pro
• The user would likely have no trouble feeling the
  vibration
• Con
• Ability to differentiate between successive
  vibrations may be difficult at high tempos

9
Option Compression

• Another possible option for the stimulus would be
  a band around the arm, leg, or lower back which
  squeezed the user to the selected beat
• The compression would be produced by a solenoid
  which shortened the band for each beat
• Pro
• Comfort
• Con
• Uniform compression may be difficult to achieve
• Complicated construction

10
Option Shock

• A small shock could be provided to the user to
  represent the beat or time of the music
• There are several problems with this option
  including user safety, variability in shock based
  on user skin conditions (e.g. sweating), and user
  comfort

11
Option Tap

• The tactile stimulus could be a mechanical tap
• Generated from a solenoid directly in contact
  with the body
• Pro
• Good resolution at high tempos
• Con
• Size of solenoid

12
Design Matrix What is the form of tactile
stimulus?
Tactile Stimulus User Comfort (20) Resolution of Signal (40) Lifespan (15) Size of Tactile Generator (25) Total (100)
Tap 15 37 11 15 78
Shock 7 27 14 20 68
Vibration 14 21 12 17 64
Compression 9 24 7 13 53
13
Design Aspect Where to locate the tactile
stimulus?

• Options
• Upper Arm
• Lower Back
• Ear

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Option Upper Arm

• I-Pod elastic docking band
• Pros
• Ease of attachment
• User comfort
• Cons
• Interference with musical performance
• Tactile discrimination

15
Option Lower Back

• Anchoring-Cap idea
• Adhesive padding ring
• Cylindrical solenoid firmly positioned in durable
  plastic cap
• Pros
• Immobilized
• Visually concealed
• Cons
• Need to replace adhesive
• Possibility of discomfort due to sitting
• Tactile discrimination a question

Anchoring-Cap as a means to secure the tactile
transducer to the lower back.
16
Option Ear Attachment
Tactile transducer attached behind ear lobe.

• Ear clip, ear-formed adapter, or behind the ear
  designs
• Pros
• Most proximal to audible processing center to
  internalize tempo
• Most sensory discrimination relative to arm back
• Cons
• User specificity
• Stability

Tactile transducer embedded in a form-fitting
material.
17
Design Matrix Where to locate the tactile
stimulus?
Location of Stimulus User Comfort (30) Resolution of Signal (40) Ease of Attachment (25) Visual Appeal (5) Total (100)
Lower Back 25 30 18 4 77
Ear 22 36 17 4 79
Upper Arm 20 25 21 3 69
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Design Aspect How to attach the tactile
transducer?

• Options
• Adhesive
• Elastic
• Form-fitting

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Option Adhesive

• Pros
• Conforms to body shape
• Secure attachment
• Cons
• Adhesive will wear out
• Uncomfortable to remove

20
Option Elastic

• Pros
• Secure attachment
• Variety of options available
• Cons
• May not work for all locations

21
Option Form-Fitting

• Pros
• Conforms to body shape
• Cons
• Not as secure
• Possibly difficult to construct

22
Design Matrix How to attach the tactile
transducer?
Mode of Attachment Stability (30) User Comfort (35) Ease of Construction (20) Visual Appeal (15) Total (100)
Adhesive 24 23 16 12 75
Elastic 26 25 18 10 79
Form-Fitting 22 31 14 13 80
23
Design Aspect How to design the user interface?

• Options
• Knob/LCD display
• Buttons/LCD display
• Knob/Tick Marks

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Option Knob/LCD Display

• Pros
• User friendly
• More precise/accurate display
• Cons
• Difficult to design and construct

commons.wikimedia.org/wiki/FilePotentiometer.jpg
detail.en.china.cn/provide/detail,1078195290.html
25
Option Buttons/LCD Display

• Pros
• Very user friendly
• More precise/accurate display
• Cons
• Very difficult to design and construct

http//www.bigfoto.com/sites/galery/closeup1/digit
al-camera-buttons.jpg
detail.en.china.cn/provide/detail,1078195290.html
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Option Knob/ Tick Marks

• Pros
• Easiest to construct
• Most cost-effective option
• Cons
• Least accurate/precise option

commons.wikimedia.org/wiki/FilePotentiometer.jpg
http//www.telerik.com/help/wpf/images/RadialScale
TickMarks-Desc.png
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Design Matrix How to design the user interface?
User Input/ Output Ease of Use (30) Ease of Construction (25) Cost (15) Accuracy/ Precision (30) Total (100)
Knob/Tick Marks 24 24 13 22 83
Knob/LCD display 26 18 10 27 81
Buttons/LCD display 28 13 9 28 78
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Final Design Summary

• Case contains protruding knob/potentiometer
• Tick marks indicate tempo (aligned with knob)
• Case outputs to tactile stimulus via an output
  jack
• Tactile stimulus attaches to user in ear-specific
  manner, delivers tempo

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Ethical Considerations

• Device is intended for human users
• Safety is a must
• Long duration of use
• Tactile device must be safe for continuous use
• Tactile stimulus concerns

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Future Work

• Construction
• Testing
• Compare musicians using tactile metronome to
  visual and audio metronomes
• Determine if resolution changes with excessive
  background sound
• More user-friendly interface
• Programmable tempos
• Bluetooth synchronization among multiple users

31
Acknowledgments

• We would like to thank
• Dr. Bill Fahl, client
• Vanessa Young, client
• Dr. Paul Thompson, advisor
• Amit Nimunkar, electronics assistance

32
Questions