How Maximum Sound Pressure Level Is Used in DAQmx AI Microphone Task

Updated Aug 9, 2019

Reported In

Hardware

  • Multifunction I/O Device

Driver

  • NI-DAQmx

Issue Details

DAQmx Create Channel (AI-Sound Pressure-Microphone).vi has maximum sound pressure level input terminal. What is this input terminal used for?

Solution

It is used to determine appropriate voltage range and gain for DAQmx device in executing the task so that it can maximize performance of ADC.

The value specified in maximum sound pressure level input terminal is in unit of decibels (dB), and you can convert it to maximum sound pressure in unit of Pascals (Pa) from the equation described in here.
Additionally, maximum sound pressure in Pa is related to the maximum voltage level with the following equation, which can be used to determine what voltage range will be selected for specified maximum sound pressure levelĀ and microphone sensitivity in your task.

Maximum Sound Pressure [Pa] = Maximum Voltage Level [V] / (Microphone Sensitivity [mV/Pa] / 1000)

Please refer to the specification sheet of your DAQmx device for what voltage range can be selected.