Knowledge Base

General Information

UltraVox XT has been thoroughly tested with the full-spectrum microphone Pettersson M500-384, specifically designed for recording ultrasonic vocalizations. This microphone has a sample rate 384 kHz and can record ultrasound up to 160 kHz.

Connect the Microphone

To connect multiple microphones to the PC, use a multi-port USB 3.0 interface card. See Install the USB 3.0 Interface Card.

Alternatively, use a powered USB 3.0 hub. USB hubs that are not powered do not work with those microphones.

IMPORTANT When using 384-kHz microphones, we recommend to use a Windows 11 computer. These microphones are not recognized in Windows 8.

Notes

The Dodotronic Ultramic 250 is not officially supported. However, short tests carried out with UltraVox XT 4 on Dell 3680 desktop with Windows 11 version 24H2 did not reveal significant issues.

See also: Connect Multiple Microphones with a USB Hub

Connect Microphones to the PC

When using 384-kHz microphones, we recommend to use a multi-port USB 3.0 interface card. See Install the USB 3.0 Interface Card.

Connect the microphones using the USB cables that come with the microphones.

• Type A plug goes to the USB 3 (recommended) port of your PC. USB 3.0 connectors and ports can be recognized by their symbols, and often also by their blue color coding.
• Type Mini-B plug goes to the microphone.

IMPORTANT Always connect the same microphone to the same USB port. If you purchased a PC together with UltraVox XT, microphones and USB ports are labeled. Always make sure that microphones are plugged into the USB ports with the matching labels.

See also: Microphone Position

Connect Multiple Microphones with a USB Hub

When you work with UltraVox XT installed on a laptop, use a powered USB 3 hub.

NOTE A powered, or active, USB hub is powered through a wall outlet to bring each hub port to the same energy level as an on-system port. Non-powered, or passive, USB hubs do not have an external power source and only pull power from the computer's USB port.

Maximum Number of Microphones

The number of microphones that you can use simultaneously depends on your UltraVox XT license. This is specified in the UltraVox XT license.

1. Choose Help > About UltraVox XT.
2. Click License Info.
3. Next to Number of microphones you see how many microphones you can use simultaneously.

See: Activate Your License

Microphone Position

Position the microphone in such a way that it receives sound optimally to minimize the effect of the position of the animal in the test environment. Here we report basic examples from the literature.

Test Setups

• Home cage observation: Microphones are positioned suspended 2 to 20 cm above the cage, pointing downward. Testing cages are generally placed in a sound-attenuating chamber.
• Separation test for rodent pups: Pups are placed into an empty container located inside a sound-attenuating chamber. The microphone is placed through a hole in the middle of the cover of the chamber, about 20 cm above the pup.
• Self-administration chamber: Position the microphone outside the chamber behind a mesh screen, if possible between the response levers at approximately head-level of the animal.
• Male-female interaction (rats): The test cage is divided in two compartments, the lower one for the male, and the upper one for the female. The microphone is attached to the divider, pointing to the lower compartment. Holes are drilled into the dividing panel to allow odor to pass to the male chamber. The diameter of the holes is smaller than the 50-kHz vocalization wavelength to sufficiently attenuate female vocalizations (Ciucci et al., Behav Brain Res. : 284–289, 2007).
• Male-male interaction (rats): In this setup, a male rat is paired with another male and housed throughout the experiment period. Each pair is housed in a polycarbonate cage (26 cm width x 43 cm depth x 20 cm height) in an environmentally controlled rearing system where temperature and humidity are kept constant and external sound and light sources are shut out. The microphones were suspended close to the lid of the cage (Takahashi et al., PLoS ONE (11): e14115, 2010. doi:10.1371/journal.pone.00141152010).

Eliciting Vocalizations for Test Purposes

For optimal gain adjustment, it is important that animals produce vocalizations. To trigger vocalizations:

• For mother-pup interaction: Separate the pups.
• For male-male interactions (mice): Add bedding contaminated with urine of another male in the cage.
• For male-female interactions (mice): Wild-derived male mice increase the number and diversity of courtship vocalizations if they previously interacted with a female (Zala et al 2020). The exposure to a female partner or to the urine induces a clear USV response in adult male mice with previous reproductive experience (Holy and Guo 2005, Maggio et al. 1983; Nyby 2001, Whitney and Nyby 1979).
• For prairie voles: Put two individuals in the cage (e.g. same-sex siblings). The frequency of vocalizations is reduced when the animals are placed in separate, side-by-side cages. For single-individual recordings, optimal distance is about 15 cm (6 in) (Stewart A.M. PhD thesis, University of Illinois at Chicago, 2012).

Relevant Literature

Browse to http://www.noldus.com/search-publications, then under Products click UltraVox.

Animal Care Guidelines

http://www.animalethics.org.au/policies-and-guidelines/animal-care

Adjust the Microphone Gain in UltraVox XT

Aim: With the Gain function you can adjust the amplification of the signal from the microphone.

NOTE If adjusting the microphone gain in the software does not give the expected results, you can also Adjust the Microphone Internal Gain.

Procedure

1. Place the microphones at the top of the cage, pointing down to the middle.
2. Click the name of the microphone you want to adjust, and then click the Settings icon.
3. In the Microphone settings window, click the Start monitoring button.
4. The Amplitude plot (top) and the Spectrogram plot (bottom) show the real-time values.
5. Move the Gain slider in such a way that the peak of the waveforms (almost) never cross the red shaded area of the Amplitude plot.
6. In the spectrogram, the calls should be clearly visible, provided that the subject emits vocalizations. See Eliciting Vocalizations for Test Purposes.
7. When ready, click the Stop monitoring button, then click OK.
8. The current value of gain is shown in the Gain column.

Repeat the steps above for the next microphone.

Source: UltraVox XT 4 - MICS, Noldus Information Technology