Here is a fast, simple method for automated data acquisition and visualization of sound directivity, made convenient and accessible via a smartphone app. The app synchronizes measurements of sound volume with the phones angular orientation obtained from either compass, gyroscope or accelerometer sensors and produces a graph and exportable data file. It is generalizable to various sound sources and receivers via the use of an input-jack-adaptor to supplant the smartphones (omnidirectional) microphone. Results are fully adequate for introductory electro-acoustics experiments and demos.
Instructions:
- For horizontal rotations, select either the Compass or Gyroscope ("Gyro: Yaw", preferred) settings. For vertical rotations, use "Accel: Gravity."
- A "VU meter" bar is provided to check the input level
- When you press Start, the plot will begin at an angle of "0", which is assumed to be straight-on toward the center of the sound source.
- After pressing "Stop", you can adjust the dB value at the origin by moving the "dbMin" slider at the bottom of the screen.
- Using iTunes File Sharing, a .CSV file called "data.csv" is available, which includes a dump of the recent measurements, for use in exporting to other graphing & analysis programs, e.g. Excel.
Example measurements and further discussion will be available in a journal paper under submission with _The_Physics_Teacher_.