Voice Scale

“Voice Scale” is a sound-level meter for preschool children, which helps them better understand their voice levels. Instead of a numerical value, as displayed in a normal sound-level meter, “Voice Scale” displays illustrations of animals, depending on the input sound level.

- Setting
1. Images can be selected from iPhone (iPad) photo albums.
2. Number of images, corresponding sound levels, and averaging time can be changed.
- Calibration: A-weighted sound pressure level.
- 1/3 oct. Band Frequency Analyzer: Flat and A-weighted frequency characteristics.
- Log file output of setting information: Using iTunes, the log file can be seen.

Calculation method: The fast Fourier transform (FFT) algorithm is used for time sequence signals of frame size 8192, shift size 4096, and sampling frequency 48 kHz, multiplied with the Hanning window function. After the 1/3 octave frequency band powers are calculated from the FFT result, the A-weighted sound pressure level is calculated from these powers.