The Sound Level Sensor (SLS-BTA) is a lower cost alternative to the Sound Level Meter (SLM-BTA, discontinued). It is a simple, easily-operated sensor to measure and investigate sound levels in typical classroom environments.

The Sound Level Meter offers greater accuracy and a greater range than the Sound Level Sensor, allowing deeper investigation of sound levels in a variety of environments and situations. But, it is considerably more expensive.

The following table may be helpful in determining which sensor fits your needs:

Feature Sound Level Sensor Sound Level Meter
Weighting A A and C
Range Single Range: 55 – 110 dB Two Ranges: Low (35 – 90 dB) and High (75 – 130 dB)
Resolution 0.1 dB 0.1 dB
Accuracy ± 3 dB ± 1.5 dB
Frequency Range 300 – 10,000 Hz 30 – 8,000 Hz
Stand-alone operation (on-device display)
Requires batteries

See also:
What advantages does a Vernier sound level sensor have over a smartphone sound level app?