USB Audio Option

60.00 $ USD

The USB Audio Option is only applicable to the NSRT_mk3 and NSRTW_mk3.

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Product Description

The USB Audio Option for the NSRT_mk3 and NSRTW_mk3 allows either instrument to be recognized by the host computer as a USB Microphone.

The USB Audio Option is only applicable to the NSRT_mk3 and NSRTW_mk3.


That option is useful to users who want to:

  • Use the NSRT_mk3 or NSRTW_mk3 with off-the-shelf audio analysis and processing software that can work from a USB Microphone.
  • Develop their own acoustics analysis or monitoring application on any platform that recognizes a standard USB microphone.

The USB-Microphone interface of the NSRT_mk3 and NSRTW_mk3 streams a mono audio signal, like any standard USB microphone, except the pressure signal is calibrated in Pa and weighted by the selected weighting function (A, C or Z).



  • Windows (Tested on Windows 7 and 10)
  • Mac-OS (Tested on OS-X El Captain)
  • Linux (Tested on Rasberry Pi 3b on Raspbian Buster)


There are two cases:

  • If the option is purchased together with the instrument, the instrument will be delivered already configured with the option activated.
  • If the option is purchased to install on an existing instrument, follow the procedure below to activate it:
    1. Email with the serial number of the target instrument and the invoice number for the purchase of the USB Audio Option. That serial number must be copied from the SN field in Instrument Manager and pasted in the email. This way there is no risk of typo when creating the activation key.
    2. We will email back with an activation key (a small file), and a link to the installer for activation application. The activation application only works on Windows.
    3. Download and install the activation application. Unzip the activation key, if it has been compressed for the purpose of emailing it.
    4. Connect the instrument to the PC. Make sure that ONLY the target instrument, and no other NSRT_mk3 or NSRTW_mk3 is connected to the PC. Make sure the PC has recognized the instrument and its operation LED is blinking.
    5. Run the activation application. When asked, point to the activation key that was emailed for that instrument. Make sure the activation application recognizes the type of instrument and properly indicates that it will be converted to the same instrument with the Audio option (see Figure 1).
    6. Click the Activate button (see Figure 1)
    7. After working for a few seconds, the right-side panel will indicate “Waiting for Driver Reload” (see Figure 2). That step can last for a few minutes. The PC is looking for the appropriate driver for the instrument with the Audio option. Do not interrupt that step or disconnect the instrument.
    8. After reloading the driver, the new firmware will be installed. That step takes a few seconds.
    9. In the end, a completion message will appear. At that time make sure the PC has loaded the generic audio driver for the Audio interface. The NSRTW_mk3_Audio should appear in the recording devices. It is possible that the PC will still be trying to find and load a generic driver for the Audio interface. If so, wait until the PC has finished loading the Audio driver and recognized the instrument as a recording device. Do not disconnect the instrument until the PC has loaded the Audio driver. That step can take a few minutes.


Figure 1

Figure 2





PCM 16-bit integer, IEEE 32-bit float

Sampling rates

32 kHz, 48 kHz

Volume and Mute

Volume and mute can be adjusted through the audio interface. The volume has no effect when the IEEE float format is chosen. In that case the sample values represent the sound pressure, scaled in Pa, irrespective of the value of the Volume control.