How to record the frequency of a string using a phone

Click For Summary

Discussion Overview

The discussion revolves around methods to measure the frequency of a vibrating string in an experimental setup involving tension and a pulley system. Participants explore various techniques using phones and other simple tools to capture the frequency, considering the challenges posed by the lack of resonance.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes an experiment with a string under tension and seeks methods to measure its frequency using a phone or simple means.
  • Another suggests using a notebook computer with Audacity for recording, but notes the challenge of the string not producing an audible frequency due to lack of resonance.
  • A participant proposes that vibrations can be detected through direct contact, mentioning the use of a cell phone or contact tuner to capture vibrations from the string.
  • Suggestions include using a cheap suction cup microphone to capture vibrations from the string.
  • Some participants recommend using guitar strings with a guitar pickup connected to a CRO, while noting that electric guitar pickups may affect the pitch of the string due to their operational principles.
  • Concerns are raised about systematic errors introduced by pickups, with references to different types of pickups that may mitigate these issues.
  • A participant questions whether the string vibrates within the audio range, specifically between 100 Hz and 10 kHz.

Areas of Agreement / Disagreement

Participants express various methods and tools for measuring frequency, but there is no consensus on the best approach or resolution of the challenges presented by the lack of resonance and potential systematic errors.

Contextual Notes

Participants acknowledge limitations related to the string's ability to produce audible frequencies and the effects of different measurement tools on the string's tension and pitch.

Ordinary
Messages
2
Reaction score
0
I am currently conducting an experiment where I attach a string to a fixed end and run the other end over a pulley (assuming zero friction). A weight is tied to the end to create tension. We currently have length, mass per unit -length and tension, the only issue is measuring the frequency of the string. Is there any way to use a phone or other simple means to record or measure this?
 
Physics news on Phys.org
Ordinary said:
The only issue is that there is nothing for the sound to resonate against meaning the string does not create an audible frequency.
Well the strings energy is going somewhere. In a loud backstage area, too loud to tune an unplugged electric guitar by ear, you can bite down on a guitar headstock and hear enough to tune up. Vibrations are transferred directly to your ear drums. The modern equivalent is to touch your cell phone to your guitar and use a tuner app (or use a contact tuner). If that doesn't work a contact transducer can be used, sandwich it wherever vibrations are transmitted, coin piezo's are just a few cents each.
 
Something must be vibrating. Buy a cheap suction cup microphone and attach it.
 
Use guitar strings and a guitar pick up attached to a CRO.
 
houlahound said:
Use guitar strings and a guitar pick up attached to a CRO.

Regular electric guitar pick up affect the pitch of the string, it's inherent to their operation, the string must be in the magnetic field and so it's tension is increased. Not a problem for music as it's normally below the human pitch perception threshold (or is swamped by other factors) but may be a problem for a science experiment.
 
Ordinary said:
The only issue is that there is nothing for the sound to resonate against meaning the string does not create an audible frequency.

Does the string vibrate within the audio range (say 100 Hz - 10 kHz)?
 

Similar threads

Undergrad Tension in a Guitar String and Frequency
  • · Replies 15 ·
Replies
15
Views
10K
Effect of temperature on vibrational frequency of a violin string
  • · Replies 5 ·
Replies
5
Views
2K
Undergrad Wavelength to Frequency Relationship in Musical Notes
  • · Replies 11 ·
Replies
11
Views
6K
Waves and vibrations on a string
  • · Replies 2 ·
Replies
2
Views
2K
Graduate Frequency and String Tension (backwards)
  • · Replies 5 ·
Replies
5
Views
5K
Undergrad How will the pitch of a string change when I stretch it? (sound)
  • · Replies 64 ·
3
Replies
64
Views
7K
Undergrad Wave Amplification & Frequency Transformation
  • · Replies 1 ·
Replies
1
Views
2K
Guitar string tension: effect of total length - continued
  • · Replies 5 ·
Replies
5
Views
3K
Undergrad Writing about a simple physics lab
  • · Replies 3 ·
Replies
3
Views
1K
MHB Calculating Tension + Length of String for Connected Particles
  • · Replies 9 ·
Replies
9
Views
2K