Pitch and Frequecy

When an object, such as a tuning fork or particles in the air, vibrates, a sound wave is created. The frequency of this sound wave is how often the particles vibrate as the wave travels. This frequency is measured in Hertz, where one Hertz is equal to one vibration per second. When these vibrations in the air hit the human ear, they are processed and transmitted via auditory nerves.

  • Frequency
    • All particles disturbed by a sound wave vibrate at the same frequency, because each particle is bumping the next causing it to move.
    • The human ear can detect sound waves with frequencies from 20 Hz to 20 KHz
    • “The sensation of a frequency is commonly referred to as the pitch of a sound.”
    • Most people can tell when two sounds have different frequencies greater than 7 Hz because of the interference and superposition of the two waves.
    • The first audio sample of Dr. Lau’s guitar is tuned to use the E2, A2, D3, G3, B3, and E4 notes or “standard” guitar tuning with frequencies (82.41, 110.00, 146.83, 196.00, 246.94, 329.63) in Hertz.
  • Pitch = human ear’s perception of frequency of a sound vibration
    • High pitch corresponds to high sound and vice versa.
    • “Certain sound waves when played (and heard) simultaneously will produce a particularly pleasant sensation when heard are said to be consonant.”
    • low pitch = low frequency
    • high pitch = high frequency
    • Units of subjective pitch = megs
    • Frequency/pitch relationship is non-linear
    • Pitch changes as loudness increases



Design and Construction Team Update

Circuit DesingToday we met up with our parts to begin working on the construction of the circuit. We were able to set it up except for the 9 V batteries because we don’t have those yet. We also will have to solder wires to the potentiometer to connect it to the breadboard and connect the microphone input to our circuit. Our design is based on an Arduino Audio Input instructable. Our code will be based on an Arduino Frequency Detection instructable. Both of these links will be posted below. We are also working on a Fritzing diagram for our circuit. We plan on having a working project by April 21st.

The circuit diagram is from http://www.instructables.com/id/Arduino-Audio-Input/





Team Assignments and Responsibilities

Research and Documentation Team: Isaac Ortiz, Abigail Shelton

  • Document our group’s progress on WordPress website 1-2 times per week through blog posts, photos, and videos
  • Visit other teams’ websites each week and share their successes and failures with the rest of our group to better our own project
  • Create the final online presentation
    • Research pitch and frequency; write an explanation of pitch verses frequency at a middle/high school level which will be published on final online presentation
    • Write explanation of how our work can be implemented by others which will be published on the online presentation
    • Collaborate with the Design and Construction Team to include data, source code, and circuit drawings into the online presentation

Design and Construction Team: Darin Elis, MaKayla Maynard, Chris Pratt

  • Develop pitch detection algorithm and write step-by-step explanation how it works which will be publish on final online presentation
  • Order hardware parts and construct the pitch detector
  • Write explanation on how the algorithm works with the hardware which will be published on final online presentation
  • Test the final product and record data; determine the success rate of the pitch detector
  • Prepare data, source code, and circuit drawings to be published on final online presentation

Parts Order

Radio Shack

  • PC-Mount Condenser Microphone Element (2)
  • 1/8-Inch Mono Inline Audio Jack 2-Pack (2)
  • 1/4-Inch Mono In-Line Audio Jack 2-Pack (2)
  • Heavy-Duty 9V Snap Connectors (2)
  • Input Amp (2)
  • Uni-Directional Dynamic Microphone (1)


  • J-FET Amplifier 2 Circuit (5)
    • Part Number: 296-1780-5-ND
  • Analog Microphone Electret Condenser Omnidirectional (3)
    • Part Number: 102-1722-ND
  • 10k Ohm Gang Linear Panel Mount Potentiometer (3)
    • Part Number: 987-1301-ND
  • 100k Ohm ±5% 0.25W Through Hole Resistor (10)
    • Part Number: CF14JT100KCT-ND
  • 10µF 16V Aluminum Capacitor (10)
    • Part Number: P5134-ND
  • 0.047µF -20%, +80% 25V Ceramic Capacitor (10)
    • Part Number: P4307-ND


Sources discovered by Darin Ellis, MaKayla Maynard, Chris Pratt, and Isaac Ortiz

Paraphrasing Lau’s Project Description “Pitch Versus Frequency”

  1. Goal of Project: Develop a device (hardware or software) that can identify a string of an electric guitar based on the sound each string produces. Achieve this goal by creating a guide (written by our team) that explains what pitch is and how a computer recognizes one pitch versus another and can be understood by a middle or high school student. Must explain exactly how it works with the aid of your own implementation.
  2. Examples of projects:
    1. Write a Matlab program that reads in an audio file from disk and says at the end of the file what string it processed. Could be a very robust pitch detector.
    2. Write an algorithm that fits inside an Arduino and build a digital tuner that turns on a unique LED for each string.
    3. Use tools in Matlab Simulink to develop an algorithm and the import it to an FPGA program, implementing the unique LEDs for each string idea. (Clear winner)
    4. Rasberry Pi 3 with a touch display and connect an audio microphone, feed the PI, and write a program that draws a galvanometer on the touch display to mimic Apple’s Garage Band tuner interface. Then package the PI with a battery inside a plastic case we printed with a 3D printer. Then get a flatbed Inkjet printer to print your team’s mascot on the back of the box along with a thank you not made out to Lau.
  3. Requirements/Concrete Deliverables:
    1. Have fun with the project
    2. Entirely Online Presentation (Such that you can show it off in an interview on your cell phone) similar to an Instructable that describes what pitch is and how our software detects it.1. Site requires a sales pitch. It should be a stand alone presentation that says “Here is out project, here is what it does, and how well it does it.”
    3. Can include video files or audio files
    4. Show snippets of software and plots of results. Digital Diary of the team’s collaboration
      1. Must be open to the public
      2. Must document the progress of project including sample data, results of early algorithm implementations
      3. Document failures and successes
      4. Must be continuously documented so that other teams can follow our progress
      5. Show contributions from each team member; have each team member make their own contributions to the diary and use their name
  4. Grading Guidelines:
    1. Explain pitch vs. frequency at middle/high school level in presentation: Does the presentation accurately reflect the concept of pitch and does it differentiate pitch from frequency or tone and is the presentation appropriate for a junior high or high school student who may or may not be interested in STEM?
    2. Create working algorithm, explain exactly how it works in presentation: Does the proposed algorithm for identifying pitch have a high chance of success if expertly implemented? Is the description of the algorithm clearly stated and present intuitive interpretations of the necessary steps, i.e. does the presentation answer the question of how and why does the algorithm work?
    3. Explain how algorithm works with hardware in presentation, include data demonstrating successful implementation: Does the presentation adequately describe how the algorithm is being implemented by the team in their chosen hardware? Does the presentation include adequate and substantial data sets demonstrating a successful implementation of the algorithm, i.e. does the input and output of the system clearly demonstrate success and that the code is working as described.
    4. Explain how our work can be implemented by others: Does the presentation make clear how the system described can be extended or implemented by others? Does the presentation make data, source code, circuit drawings, or other products available to others? For instance, is there a Github account for sharing source code? Are their PCB designs that I can download and print?
    5. Evenly distribute workload between team members and document contributions: Are the contributions of individual team members clearly discernable from the rest of the group? Is there an even distribution of effort across the team? Is there continuous collaboration amongst the team? Is the online diary being kept up to date and does it thoroughly document all effort leaving out trivial tasks like basic emails back and forth between members?
    6. Utilize other projects and contribute assets to others: Is the team making use of other projects’ assets and is the team contributing assets to others? Is the team properly attributing the source of assets and referencing online content or is the team plagiarizing the work of others?

Brainstorming Session: Guidelines

  1. Group members must attend every meeting, unless they have an academic commitment. If a group member is unable to attend, they must let the group know via GroupMe as soon as possible.
  2. Group will meet every Tuesday at 3:20 PM to work on the project. The number of meetings per week may increase as the project deadline approaches.
  3. The group will update their progress 1 – 2 times a week on Storify. Group members will take turns documenting the progress.
  4. The group will specifically outline roles and expectations of each member by the next meeting.
  5. The group currently plans to take the Arduino approach, using a microphone to detect the sound, code to determine the frequency and note, and seven segment display to display the note.

The guidelines were written by all group members.