Automating ultrasonic vocalization analyses: The WAAVES program

• Automated program to analyze ultrasonic vocalization (USV) sound files was developed.
• Highly significant correlation between program output and human assessments.
• Program completes analyses in approximately 0.3% of time compared to manual methods.
• USVs shown as useful index for detecting cocaine-associated individual differences.
• Statistical analyses reveal cocaine-associated USVs predictive of cocaine intake.

BackgroundHuman emotion is a crucial component of drug abuse and addiction. Ultrasonic vocalizations (USVs) elicited by rodents are a highly translational animal model of emotion in drug abuse studies. A major roadblock to comprehensive use of USV data is the overwhelming burden to attain accurate USV assessment in a timely manner. One of the most accurate methods of analyzing USVs, human auditory detection with simultaneous spectrogram inspection, requires USV sound files to be played back 4% normal speed.New methodWAAVES (WAV-file Automated Analysis of Vocalizations Environment Specific) is an automated USV assessment program utilizing MATLAB's Signal and Image Processing Toolboxes in conjunction with a series of customized filters to separate USV calls from background noise, and accurately tabulate and categorize USVs as flat or frequency-modulated (FM) calls. In the current report, WAAVES functionality is demonstrated by USV analyses of cocaine self-administration data collected over 10 daily sessions.ResultsWAAVES counts are significantly correlated with human auditory counts (r(48) = 0.9925; p < 0.001). Statistical analyses used WAAVES output to examine individual differences in USV responses to cocaine, cocaine-associated cues and relationships between USVs, cocaine intake and locomotor activity.Comparison with existing methodWAAVES output is highly accurate and provides tabulated data in approximately 0.3% of the time required when using human auditory detection methods.ConclusionsThe development of a customized USV analysis program, such as WAAVES streamlines USV assessment and enhances the ability to utilize USVs as a tool to advance drug abuse research and ultimately develop effective treatments.