Connect the sensor following the steps in the Getting Started section of this user manual.
Go Direct Sound has four measurement channels. The channel names are
- Sound Level A-weighted
- Sound Level C-weighted
- Wave Amplitude
The default channel that is active when the sensor is connected is Microphone. This channel is used for capturing sound waveforms. Follow these guidelines to collect good waveforms:
- By default, microphone data-collection parameters are set that sample very quickly for a very brief time, effectively taking a “snapshot” of the sound waves present when data collection is started. With this in mind, start the sound source you wish to investigate before starting data collection.
- Make sure the sound level is in the correct range to produce good wave patterns. If the sound is too loud, the wave pattern will be clipped off at the top or bottom. Move the Microphone farther from the sound source or turn down the volume of the sound.
While capturing waveforms, Go Direct Sound can store up to 5000 data points. It is possible to capture high frequency (>10,000 Hz) sound waves by increasing the data-collection rate. Likewise, it is possible to capture more wave cycles, which is desirable when creating FFTs, by increasing the data-collection duration. However, Graphical Analysis will not let you select data-collection parameters that will yield more than 5000 data points per run.
Note: When connected via Bluetooth wireless technology, collecting a large number of data points will lead to a delay when the data appear in Graphical Analysis. The transfer rate of data over Bluetooth wireless technology is relatively slow compared to wired connections.
Because of the unique data-collection parameters required to capture a waveform, this channel cannot be active if any of the other channels (sound level or wave amplitude) are selected.
There are two Sound Level channels: A-weighted and C-weighted. The A‑weighted channel applies a filter to the sound level reading that mimics the human ear’s response to loudness and frequency. In most classroom situations, you'll want to measure A-weighted sound levels. For more information on the difference between A- and C-weighted sound levels, see www.vernier.com/til/3500
The microphone is located inside the hole in the top of the case. Because the microphone is located inside the sensor, it is helpful to point the microphone hole toward the source of the sounds you are measuring.
When using the sensor, be mindful of the environment around it. Wind blowing across the opening or vibrations from the surface on which it is resting can cause the sensor to read much higher sound levels than it should. When collecting data, place the sensor on a soft surface or hold the sensor in your hand to separate the microphone from extraneous vibrations.
Example Sound Levels
|Threshold of pain
|Busy traffic, normal radio
|Normal conversation, dishwasher
|Threshold of hearing
The Wave Amplitude channel only reports the amplitude of the waveform, rather than capturing an entire waveform. The wave amplitude is not the same as the sound intensity or sound level, but it is related to them.
If you would like to investigate the logarithmic nature of the decibel scale, collect both sound level and wave amplitude data at the same time. The wave intensity is proportional to the square of the wave amplitude. Plotting sound level vs. wave intensity will produce a logarithmic graph.