Physiological Physiological MetronomeMetronome

Adam Pala, Ben Fleming, Cole Drifka, Jeff Theisen

Clients: Dr. Bill Fahl, Dept. of OncologyVanessa Young, Carnegie Mellon music student

Advisor: Dr. Paul Thompson, Dept. of Biomedical Engineering

BackgroundBackground

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

Design MotivationDesign MotivationThe 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

Client Requirements and Design Client Requirements and Design ConstraintsConstraints

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)

““Constant/Permanent” Constant/Permanent” Features of the DesignFeatures of the Design

The circuit (with slight modifications)

Original: http://electroschematics.com/216/electronic-metronome-circuit-schematic/

““Constant/Permanent” Constant/Permanent” Features of the DesignFeatures of the Design

The case

http://www.hammondmfg.com/pdf/1593P.pdf

Design Aspect: Design Aspect: What is the form of What is the form of tactile stimulus?tactile stimulus?

Options:

VibrationCompressionShockTap

Option: Option: VibrationVibrationOne 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 vibrationCon

◦ Ability to differentiate between successive vibrations may be difficult at high tempos

Option:Option: Compression CompressionAnother 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

Option: Option: ShockShock

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

Option: Option: TapTap

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

Design Matrix: Design Matrix: What is the form of What is the form of tactile stimulus?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

Design Aspect: Design Aspect: Where to locate the Where to locate the tactile stimulus?tactile stimulus?

Options:

Upper ArmLower BackEar

Option:Option: Upper Arm Upper ArmI-Pod elastic

docking band

Pros◦Ease of attachment◦User comfort

Cons◦Interference with

musical performance

◦Tactile discrimination

Option:Option: Lower Back Lower Back

“Anchoring-Cap” ideaAdhesive padding ringCylindrical 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.

Option:Option: Ear Attachment Ear Attachment

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.

Tactile transducer attached behind ear lobe.

Design Matrix: Design Matrix: Where to locate the Where to locate the tactile stimulus?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

Design Aspect: Design Aspect: How to attach the How to attach the tactile transducer?tactile transducer?

Options:

AdhesiveElasticForm-fitting

Option: Option: AdhesiveAdhesive•Pros•Conforms to body shape•Secure attachment

•Cons•Adhesive will wear out•Uncomfortable to remove

Option: Option: ElasticElastic•Pros•Secure attachment•Variety of options available

•Cons•May not work for all locations

Option: Option: Form-FittingForm-Fitting•Pros•Conforms to body shape

•Cons•Not as secure•Possibly difficult to construct

Design Matrix: Design Matrix: How to attach the How to attach the tactile transducer?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

Design Aspect: Design Aspect: How to design the user How to design the user interface?interface?

Options:

Knob/LCD displayButtons/LCD displayKnob/Tick Marks

Option:Option: Knob/LCD Display Knob/LCD Display

commons.wikimedia.org/wiki/File:Potentiometer.jpg

detail.en.china.cn/provide/detail,1078195290.html

Option:Option: Buttons/LCD Buttons/LCD DisplayDisplay

http://www.bigfoto.com/sites/galery/closeup1/digital-camera-buttons.jpg

detail.en.china.cn/provide/detail,1078195290.html

Option:Option: Knob/ Tick Marks Knob/ Tick MarksPros Easiest to constructMost cost-effective optionCons Least accurate/precise

optioncommons.wikimedia.org/wiki/File:Potentiometer.jpg

http://www.telerik.com/help/wpf/images/RadialScaleTickMarks-Desc.png

Design Matrix: Design Matrix: How to design the user How to design the user interface?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

Final Design SummaryFinal Design SummaryCase contains protruding

knob/potentiometerTick marks indicate tempo (aligned with

knob)Case outputs to tactile stimulus via an

output jackTactile stimulus attaches to user in ear-

specific manner, delivers tempo

Ethical ConsiderationsEthical 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

Future WorkFuture WorkConstructionTesting:

◦Compare musicians using tactile metronome to visual and audio metronomes

◦Determine if resolution changes with excessive background sound

More user-friendly interfaceProgrammable temposBluetooth synchronization among

multiple users

Acknowledgments Acknowledgments

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

assistance

Questions:Questions: