Voice Spectrogram Logger vs Audio Narrowband Filter

1. DESPLAY The spectrogram of voice is displayed in the range of 20 - 2500Hz. You can zoom in/out the spectrogram by pinching in/out smoothly. Also landscape orientation is supported. 2. USEFUL By moving "vivid" slider, the gradation of spectrogram is controlled. The gradation is also controlled by moving "baseline" slider in "Setting" tab and selecting "Mean" or "RMS" as the way of smoothing the spectrogram out. 3. LOGGING When "log" switch is ON, this app runs in the logging mode. To choose a past log from "History" tab, you can pull it from iPhone via email as a PNG file. 4. AVAILABLE Without cellular data service, the full functions are available. The background processing is supported. 5. TECHNICAL NOTE Sample rate: 44.1kHz Bit depth: 32bit float FFT window function: Blackman FFT samples: 4096

This app implements an audio filter around any selected pitch from C2 to C8. The sound from the microphone is filtered according to parameters set by the user and played back to the user, preferably over a headset. The app features a selectable filter bandwidth from 400 cents to 30 cents. The purpose of this filter is to help in training aural piano tuners. When playing an interval, the aural tuner needs to be able to focus on a coincident partial of the two notes to assess the beat rate at that partial. If this filter is set to isolate that coincident partial then the job of picking out the desired pitch is easier. Once the user has learned to focus on coincident partials this filter will not be necessary. This is a training tool, not a tool for everyday use. In addition to the filtering function this app also provides a synthesizer function that synthesizes a pure tone beating at a user-specified rate. The purpose of this synthesizer is for training aural piano tuners to recognize beat rates. The synthesized beat rates can be set from 1/10 beat per second to 30 beats per second. The beat rates of these "rapidly beating intervals" are especially difficult to assess when they are too fast to count. By listening to a synthesized beat at a specified beat rate the user can develop a sense of recognizing that beat rate in an interval played on the piano.