The Sound Spectrum Viewer Interactive is an adjustable-size file that displays nicely on smart phones, on tablets such as the iPad, on Chromebooks, and on laptops and desktops. The size of the Interactive can be scaled to fit the device that it is displayed on. The compatibility with smart phones, iPads, other tablets, and Chromebooks make it a perfect tool for use in a 1:1 classroom. When the app starts up, it will request permission from the user to utilize their device microphone. This is a standard security measure for all devices whenever an app (such as your browser) needs to utilize a device resource that is not otherwise permitted by the app. The Physics Classroom is requesting use of the microphone in order to send signals and receive signals.

 

Sound Spectrum Viewer is a tool. It is not a simulation. It is a tool that can be used to capture a sound and display its spectrum or an FFT analysis. (FFT=Fast Fourier Transform) It works best when the source source is near to the microphone of the device on which Sound Spectrum Viewer is being used. The interactive will capture sound from the intended source and all background sound or noise. As such, using the Interactive in a relatively quiet environment also enhances the quality of the analysis. To begin the sound capture process, tap on the Play button in the lower left corner of the Interactive. Sounds will continue to be captured and displayed until the Pause button is tapped. Users can toggle between Spectrogram Mode and FFT Mode by tapping the Go to ... button in the top-right corner.

The Interactive displays a spectrogram of the sound that it captures. A spectrogram is a real-time, visual representation of the sound frequency and intensity over the course of time. The frequency is plotted along the vertical axis and the time is plotted along the horizontal axis. The most currently-recorded sounds are displayed on the right side of the graph. In this sense, "now" is on the far right. The amplitude or intensity of the sound is represented by the color. Spectrograms are sometimes referred to as sonographs or voiceprints.

The Interactive will also display the Fast Fourier Transform of the collected sound. The FFT display plots the frequency along the horizontal axis and the amplitude along the vertical axis. The FFT is a dynamic display that constantly changes with time to reflect the latest sound gathered from the device microphone. It is very useful for analyzing the sound produced by a musical instrument. The harmonic frequencies will rise above the noise as frequency peaks. For best results, play the instrument, collect the sound and be ready to tap on the Pause button was a relatively good FFT display appears. The frequency of the most dominant peak will be displayed on the screen.

Our original intent was to provide this tool as an accompaniment to the Data Transmission Interactive. Our thought was that students could use Sound Spectrum Viewer to analyze the spectrum of the sound transmitted by Data Transmission. An interesting study involves analyzing the spectrogram of a message transmitted using the Single Frequency mode and comparing it to the same message being transmitted using the 16-bit mode.

Since the original release, we have added the FFT display. The FFT display opens up a variety of new possibilities for classrooms using this tool. While this was our reason for creating the Interactive, we are sure that users will find other uses of this tool. It is a supurb tool for supporting student project work. As a tool, it has wide application.

 

Related Resources

• Communicating with Waves
  This NGSS-inspired task includes three parts that focus on the sending, encoding, and storage of information by means of electromagnetic waves.
  
   

• Digitizing Data
  This NGSS-inspired task addresses the manner in which data (such as graphic images) can be digitized and the issues associated with the transmitting, receiving, and storage of digital data.

 

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