Summary

Written By Collin Duffy

Audio Connections

Functions

begin(threshold);

Initialize and start detecting frequencies, with an initial threshold (the amount of allowed uncertainty).

available();

Returns true (non-zero) when a valid frequency is detected.

read();

Read the detected frequency.

probability();

Return the level of certainty, betweeo 0 to 1.0.

threshold(level);

Set the detection threshold, the amount of allowed uncertainty.

Examples

File > Examples > Audio > Analysis > NoteFrequency

Notes

The YIN algorithm (PDF) is used to detect frequencies, with many optimizations for frequencies between 29-400Hz. This algorithm can be somewhat memory and processor hungry but will allow you to detect with fairly good accuracy the fundamental frequencies from electric guitars and basses.

Within the code, AUDIO_GUITARTUNER_BLOCKS may be edited to control low frequency range. The default (24) allows measurement down to 29.14 Hz, or B(flat)0.

TODO: The usable upper range of this object is not well known. Duff says "it should be good up to 1000Hz", but may have trouble at 4 kHz. Please post feedback here, ideally with audio clips for the NoteFrequency example.

This object was contributed by Collin Duffy from his AudioTuner project. Additional details and documentation may be found there.