With the Phase Flip Simulator you’re able to rotate one copy of a tone against another. This allows you to listen to what happens when phase shift between sound reinforcement and cancellation. The controls are all handled by your mouse that can click and drag across the interface elements. Alternatively, you can make accurate changes using the keys on your computer keyboard.
It’s a useful learning tool about amplitude summation, polarity, and time delays in audio signal. To turn on the audio engine, click the Energize the pair button. It create a continuous sine wave tone that then divides into two pathway: one (Path A) is the unchanging reference sound; the other (Path B) is the copy that will be manipulated.
How to Use the Phase Flip Simulator
By adjusting the Frequency slider, from 80 Hz through 880 Hz, you change the pitch of the tone. The lower frequencies is better for perceiving small differences such as a shift in volume or timbre, whereas the high ones show the comb filtering effects more clearly.
Visualize phase relationships. The main knob in the middle is where you can see the relationship between your two phase-shifted signal. By dragging the pointer around the circle, you’re rotating the phase of signal B against signal A. The amber line depicts the copy that’s been shifted; it follow along behind the violet line (the reference signal). Below the dial, a readout tells what the current angle is and explains if it’s reinforcing or opposing.
When it’s at zero degrees, your waves will be in perfect alignment, resulting in constructive interference, which increase the volume about six decibels. The Micro-delay slider provide millisecond-precise offsets for adjusting delays. When combined with the phase rotation, it shows how a physical delay correspond to phase angle across frequencies. Below the waveforms is a read-out of the effective overall delay (and resulting amplitude ratio). You can watch as the total sum waveform (in bold black) expand and contract according to the interference patterning in real-time.
With the Flip B polarity button, the second signal’s phase is inverted by exactly one hundred and eighty degrees. This is like flicking a phase switch on an input on your mixing console. It allows you to get a feel for where a hard polarity inversion is different than a pure phase rotation. When the levels are matched perfectly, you will be able to hear silence by setting the Park at the null button to automatically set the phase to a point of maximum cancellation.
Without having to reach for your mouse, there are also keyboard shortcuts that allow you to quickly use the simulator. When pressed, the space bar acts as a power switch turning the audio on/off. Pressing the letter N will park the system at the null point, which cancels any signal immediately. And the letter O engages a smooth turn of the phase angle in three seconds, allowing you to listen as it continue the transition through all phase states.
To keep your ears safe when experimenting, there’s a Master level slider that controls total output volume. If you click on the phase dial and want to get more precise with its control, use the arrow keys to adjust it. To make big jumps (fifteen degree increments) around the dial, press Shift along with your arrow key. The Fullscreen button takes the interface out of the way so you have plenty of space to view the visualizations without distraction.
A good place to start is on a low value for the frequency such as 100 Hz and then drag your phase dial from zero to one hundred and eighty degrees at a slow pace. You should of notice that the volume drops as the waves begin to oppose each other. Gradually raise the frequency and do it again until you hear how more high-pitched sounds is more sensitive to small amounts of phase error. Switch the polarity to compare a hard inversion against a smooth phase rotation. Listen for what happens to the sum waveform in both situations.
The beauty of this simulator is that it connects the dots between what we know from wave theory to what we hear. There’s no chance of damaging anything or going into clip territory while using it. Playing with the buttons and sliders gives you a naturaly understanding about the relationship between polarity, timing, and the end result.
Go ahead and turn the dial for yourself and observe what happens as these signals interact.