sound sensor & microphone

sound sensor

Sound sensors tend to find their use as stand alone noise meters but this misses some interesting uses where sound level changes over time. Just using it as a class noise meter is one option to try. It finds its main use as a marker sensor when recording over time. For example, it might provide a clue that people were causing a room to warm up. Other uses such as testing the loudness of sounds or comparing sound insulators will work if you can reduce the background noise. Note that the sound sensor usually measures over a range that starts above zero. In common with noise meters, they are ‘A-weighted’ – meaning that their response has been adjusted to match that of the human ear. 

Possible uses

• Sound travel through materials.
• Attack and decay characteristics of musical instruments and sounds.
• Comparing loudness of sounds. Using a data logger the sound sensor can be taken away from the computer to monitor traffic noise and the dawn chorus of birds.
• Sound insulating materials.
• Amplitude of sound with distance.
• Comparing waveforms of high and low sounds (e.g. tuning forks) using an oscilloscope or fast data logger or see below

microphone sensor

Some ranges feature a microphone as distinct from an ‘A-weighted’ sound sensor that measures noise levels in dB. The microphone may have a sufficiently fast response to allow you to measure the speed of sound and capture waveforms and this is impressive. On many systems, and there are a few exceptions, you may need to first capture the sound on a fast data logger and then transfer it to the computer. The sensor may even offer a way of switching between these functions. It is worth also seeing what you can do with an ordinary microphone connected to the sound card of the computer. Software is available to do some impressive waveform analysis.

sound switch

Used to measure the speed of sound. Two hardware approaches to this: you set a pair of microphones a certain distance apart, make a sound and then read the interval between two peaks from a graph. In another you strike two pieces of metal together and the metal closes a switch and starts the timing. Software shows the time it takes for the sound to reach a microphone. Can also be used to show how temperature affects the speed of sound or even for timing how fast an object takes to fall and hit the floor. 

I’ve rated these sensors but your assessment will be different. I give a score, out of five, for the sensor’s intrigue, interest, and learning potential. I also give a score for how often a science department might use it.