FATpick's in-app tuner detects and displays the pitch of notes played on your guitar, bass or other instrument. Use it to re-tune your instrument to an alternative tuning or to check your tuning with the same pitch detection algorithm used by the in-game tab player.
The tuner provides a graphical representation of the detected pitch and related information about the audio signal picked up by the microphone (or other input device).
Needle and Gauge
The primary component of the interface is a gauge similar to what you might find on a tuner guitar pedal or other electronic tuner. It has three parts:
The detected note (or more accurately, pitch class) is displayed at the top of the gauge, as one of the 12 notes of the chromatic scale (C, C#/Db, D, D#/Eb, E, F, F#/Gb, G, G#/Ab, A, A#/Bb, B). This is the name of the note that is closest to the primary pitch currently detected in the input signal.
The needle indicates how close the pitch is to the exact frequency of the detected note. The needle will hover near the center of the gauge when the detected pitch is close to the expected frequency. When the current frequency is slightly flat (below the expected value) the needle will point to the left of center. When slightly sharp (above the expected frequency) the needle will point to the right. Since natural fluctuations can make it difficult to keep the needle perfectly centered at all times, anything in the center region of the gauge might be considered "in tune", but try to get the needle as close to vertical as you can.
The exact frequency of the detected pitch is displayed below the gauge, in Hz. For example, E2 (the note generated by the open 6th string in a standard guitar tuning) has frequency of approximately 82 Hz and middle C (C3) has frequency around 262 Hz.
Below the primary tuner gauge you will find a couple of other visualizations of the audio signal. These add a bit of flair, but they aren't just eye-candy. They can be used to get a better sense of how FATpick is hearing the sound of your instrument.
The spectrogram is indicates the intensity of individual frequencies in the input signal.
As you know, your guitar generates sound from the vibrations of the strings. The vibrating strings create (acoustically or electronically) variations in air pressure - sound waves - that our ears interpret as sound.
A sound wave with a specific wavelength (an oscillation at a specific frequency) creates a pure tone. For example, a string vibrating at 440 Hz (cycles per second) generates a sound wave with a wavelength of approximately 2.5 feet (~80 cm) that we call A4 (the A just above middle C).
But pure tones are rare in practice. Most of the sounds we hear aren't simple, uniform waves. In the real world sound waves are irregular and noisy. They have chaotic fluctuations from the pure form, and often overlap with other simultaneous sounds.
Because of this, in the science of digital signal processing (DSP) we think of the pitch of a given audio sample not as a wave of a single frequency by at the combination of many individual waves with different frequencies at various levels of intensity.
The spectrogram is a visual representation of this analysis. For a given frequency it indicates the strength of that component frequency in the composite sound wave found in the audio sample.
Bars in the graph represent individual frequencies, roughly over the range of human hearing, with low frequency (low pitch) sounds on the left and high frequency (high pitch) sounds on the right. The height of each bar represents the intensity of that signal in the current sample.
The peak frequency in the spectrogram is generally the pitch that appears in the tuner gauge, but the spectrogram illustrates the relative strength of the other components of the sound.
Incidentally, one interesting thing you can see with the spectrogram is the appearance of resonant frequencies or harmonics. When you play a given note on your guitar you'll typically see not just one several spikes on the spectrogram. This pattern reflects the resonant frequencies generated by your guitar: a large peak at frequency of primary pitch echoed by smaller peaks at octaves above and below the fundamental note. E.g., when you play the note E3 you'll see a large spike at 220 Hz and smaller spikes for the E note at different octaves like E2 at 110 Hz, E4 at 440 Hz, and so on.
The oscilloscope is a "picture" of the sound wave found in input signal.
A digital microphone measures the level (volume) of the input audio tens of thousands of times per second - typically collecting 48000 or 44100 samples per second - to capture the "shape" of the sound wave.
The oscilloscope is simply a running plot or graph of samples. Each point indicates amplitude of the audio signal at a given instant in time.
On the oscilloscope you can see the "spike" in signal created by a percussive sound like plucking a guitar string, or the standing wave created by letting a string "ring".
Opening and Closing the Tuner
The electronic tuner tool is found in FATpick's Tools Menu, and is rarely more than two clicks away from any screen in the app.
To open it:
Open the tools menu by clicking on the toolbox in the navigation buttons at the top of the application window (or hitting the
Tkey on your keyboard).
Select the chromatic tuner from the tools menu by clicking on the corresponding button (or hitting the
Tkey on your keyboard again).
The tuner will be active as soon as the dialog is opened, showing the pitch picked up from your live mic as long as the tuner is open.
To close the tuner, you can do any of the following:
Click the back-button (left-arrow icon) in the dialog header to return to the tools menu.
ESCbutton on your keyboard to return to the tools menu via a keyboard shortcut.
Click anywhere in the FATpick application window outside of the dialog frame to dismiss the tools dialog.