Simulator Background Properties: To open the Sound Lab simulator background Properties Box, depress Select. Then double-click or control-click in a clear area of the simulation window.

In the Properties Box, you can set uniform begin times and end times for the tape recorder and all Smart Sound Rooms, including those not yet placed. You can set a uniform frames per second rate for animation in all Smart Rooms. Finally, you can either allow (default) or not allow all measurement tools to work in Stop mode. These properties are discussed below for both Waves & Sound simulators.

• Begin time. The begin time is the time after sources start producing waves (time zero) that the simulation starts. A begin time that is identically zero allows you to watch or listen to the transient initial state. In a Ripple Tank, you can watch waves initially spread out from a point or line source. On the Tape Recorder, you can listen to musical instruments that do not send out sustained signals. In the Smart Sound Room, you can watch the wave packet generated by a piano key reflect off a wall. Or you can watch a wave pattern follow a moving point source--and listen to the Doppler-shifted sound waves coming from the Tape Recorder.
  
  A begin time much greater than zero places the simulation during the steady state. In Ripple Tanks, you can watch the steady flow of waves away from sources, around baffles, and into the walls of the tank. On Tape Recorders, you can listen to beating sound waves coming from two signal generators with signal frequencies that differ by a few Hertz. In Smart Rooms, you can watch the cyclic propagation of the same beats in different media.
  
• End time. The difference between the end time and the begin time is the duration of the simulation run. As a general rule, a simulation of an initial state should last about as long as the initial state. In Ripple Lab, a simulation of a steady state rarely needs to last longer than 1 second if the simulation loops. In Sound Lab, a steady state simulation should last long enough for an observer to grasp the physics. Usually a simulation of a few seconds, coupled with frequent replays of the simulation, will suffice.
  
  Remember: Shorter runs require less calculation time and fewer computer resources! Keep them as short as possible without sacrificing the educational value of the simulation! For Smart Rooms, refrain from animating wave patterns at all unless you are simulating transient initial states (Doppler effect, echoes) or periodic phenomena with frequencies of a few Hertz or less (like beats).
  
• Frames per Second. The animation frame rate for Ripple Tanks and Smart Sound Rooms. High frame rates provide better resolution in time. Lower frame rates require less computation time. For non-periodic phenomena like Doppler effects and echoes, choosing lower frame rates will save computation time and resources without sacrificing much resolution. For periodic phenomena like rippling waves and steady beats, you need at least two, and preferably three or four, frames per period for good resolution.

• Allow measurement tools to work in Stop mode. By default, this box is checked, meaning that measurement tools (oscilloscopes, Fourier analyzers, frequency meters, sound level meters) in Sound Lab work in Stop mode as well as Run mode. This means that, in addition to the audio feedback you get from striking most sound sources with the Hammer tool, you can get immediate feedback on frequencies, volumes, wave spectra, and the shapes and amplitudes of generated waves. You don 't need to wait for calculations to finish.
  
  If this box is not checked, measurement tools only work during Run mode. This option effectively "turns off" physics during Stop mode, except for the audio produced by the hammer.