This information pertains to LabQuest 2 and LabQuest 3.

If you have an original LabQuest, see this article.

The combination of an older version of Microphone (MCA-BTA) (shipped before August 2013), and LabQuest 2 (LABQ2) or LabQuest 3 (LABQ3), will result in waveforms that exhibit excessive high-frequency noise. If an FFT is performed, the noise peaks above 3000 Hz. The noise is only visible when viewing low-amplitude waveforms, such as from a tuning fork.

Unfortunately, there is no workaround. If you have both Microphones made before August 29, 2013 and LabQuest 2 or LabQuest 3 interfaces that show excessive noise, Vernier will replace the older Microphones with newer versions that are resistant to the interaction with these LabQuest units. Contact Vernier technical support to request an exchange.

We have also had reports of the same effect showing up when these Microphones are used with the TI-Nspire Lab Cradle TI-Nspire Lab Cradle (TI-NSLABC)

Older Microphones all work well with LabPro (LABPRO), regardless of labeling or age. The noise is created by an interaction between the Microphone and LabQuest 2 or LabQuest 3.

Microphones made after Sept 2011 work well with the original LabQuest. See:
LabQuest (original) and LabQuest Mini: Readings from my Vernier Microphone are very noisy.

How can I generate a clean sine wave sound output from a LabQuest?
What is the best procedure to get a clean sine wave when using a tuning fork with the microphone?