HP StreamSmart Sound Probe

The sound probe contains a microphone with variable capacitor. One of the capacitor’s plates is actually a sound-sensitive membrane, moving back and forth as sound waves resonate through it. This capacitor is connected serial to a resistor. When the capacitor is charged, and sound waves move the membrane, which is one of the capacitor plates, the distance between the plates change, the capacity of the capacitor changes and the voltage on the capacitor and on the resistance changes. This voltage is then adjusted to a range of 0-5 V, accepted by the Analog-Digital converter of the data logger, and transformed to a value between +/-2.5 V. The proper result is then recorded and stored in the data Box’s memory. The probe has a frequency range of between 35 Hz to 10,000 Hz with a Maximum Sample Rate 20,000 samples per second.

Typical Experiments that uses the Sound Probe:

• Measuring the speed of sound.
• Measuring sound beats.
• Comparing the wave forms from various musical instruments or animals.
• Investigating how the wave pattern changes when the amplitude and the frequency are changed.

Data can be easily be cropped and export to the Statistics Aplet.