Simple Interference Experiment

Simple Interference Experiment is intended for students going through a physics course, or people interested in simple demonstrations in physics. This app allows generating up to four different sine wave sounds of a definite, unknown frequency. They can be played one at a time or simultaneously. When any two of the four available sounds are played at the same time beats emerge, indicating that all frequencies are relatively close to each other.
Outside a physics lab, this app could be used in conjunction with a sound frequency generator app installed in a second device in order to find out the four unknown frequencies. Playing a single sound simultaneously on each device and carefully changing the sound's frequency knob in the second device led to beats when both frequencies get close enough. Further adjustments in the direction of a decreasing beats frequency will eventually make beats disappear. At this point, the frequency in both devices is the same.
At the physics lab, in addition to the previous exercise, a faster determination of the unknown frequencies can be performed with the aid of a microphone and the appropriate hardware and software provided by Vernier, PASCO or others. In the particular case of Vernier, the experiment 32 "Sound waves and Beats" from the book Physics with Vernier, (http://www.vernier.com/experiments/pwv/32/sound_waves_and_beats/) could be revisited by using this app as the source of sounds.