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

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

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

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)

“Constant/Permanent” Features of the Design The circuit (with slight modifications) Original:

“Constant/Permanent” Features of the Design The case

Design Aspect: What is the form of tactile stimulus? Options: Vibration Compression Shock Tap

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

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

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

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

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 Shock Vibration Compression

Design Aspect: Where to locate the tactile stimulus? Options: Upper Arm Lower Back Ear

Option: Upper Arm I-Pod elastic docking band Pros ◦ Ease of attachment ◦ User comfort Cons ◦ Interference with musical performance ◦ Tactile discrimination

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.

Option: 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: 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 Ear Upper Arm

Design Aspect: How to attach the tactile transducer? Options: Adhesive Elastic Form-fitting

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

Option: Elastic Pros Secure attachment Variety of options available Cons May not work for all locations

Option: Form-Fitting Pros Conforms to body shape Cons Not as secure Possibly difficult to construct

Design Matrix: How to attach the tactile transducer? Mode of AttachmentStability (30) User Comfort (35) Ease of Construction (20) Visual Appeal (15)Total (100) Adhesive Elastic Form-Fitting

Design Aspect: How to design the user interface? Options: Knob/LCD display Buttons/LCD display Knob/Tick Marks

Option: Knob/LCD Display Pros User friendly More precise/accurate display Cons Difficult to design and construct commons.wikimedia.org/wiki/File:Potentiometer.jpg detail.en.china.cn/provide/detail, html

Option: Buttons/LCD Display Pros Very user friendly More precise/accurate display Cons Very difficult to design and construct camera-buttons.jpg detail.en.china.cn/provide/detail, html

Option: Knob/ Tick Marks Pros Easiest to construct Most cost-effective option Cons Least accurate/precise option commons.wikimedia.org/wiki/File:Potentiometer.jpg

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 Knob/LCD display Buttons/LCD display

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

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

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

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

Questions: