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ORIGINAL RESEARCH—ANATOMY/PHYSIOLOGY: Female Sexual Responses Using Signal Processing Techniques


Javad Rafiee, MSc, Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Multidisciplinary Design Lab, Department of Mechanical, Aerospace and Nuclear Engineering, Jonsson Engineering Center, 110 8th Street, Rensselaer Polytechnic Institute, Troy, NY 12180-3590, USA. Tel: 518-276-6883; Fax: 518-276-6025; E-mail:


Introduction.  An automatic algorithm for processing vaginal photoplethysmograph signals could benefit researchers investigating sexual behaviors by standardizing interlaboratory methods. Female sexual response does not co-vary consistently in the self-report and physiological domains, making the advancement of measurements difficult. Automatic processing algorithms would increase analysis efficiency. Vaginal pulse amplitude (VPA) is a method used to measure female sexual responses. However, VPA are problematic because of the movement artifacts that impinge on the signal. This article suggests a real-time approach for automatic artifact detection of VPA signals. The stochastic changes (artifacts) of VPA are characterized mathematically in this research, and a method is presented to automatically extract the frequency of interest from VPA based on the autocorrelation function and wavelet analysis. Additionally, a calculation is presented for the vaginal blood flow change rate (VBFCR) during female sexual arousal using VPA signals.

Aim.  The primary aim is to investigate the experimental VPA measures based on theoretical techniques. Particularly, the goal is to introduce an automatic monitoring system for female sexual behaviors, which may be helpful for experts of female sexuality.

Methods.  The methods in the research are divided into experimental and theoretical parts. The VPA in twenty women was measured by a common vaginal photoplethysmography system in two conditions. Each subject was tested watching a neutral video followed by an erotic video. For theoretical analysis, an approach was applied based on wavelet transform to process the VPA.

Main Outcome Measures.  Introduction of an automatic and real-time monitoring system for female sexual behaviors, automatic movement artifact detection, VBFCR, first application of wavelet transform, and correlogram in VPA analysis.

Results.  The natural and significant frequency information of VPA signals was extracted to automatically detect movement artifacts and to investigate the effects of erotic videos on female sexual responses.

Conclusions.  The computerized automatic systems based on advanced math and statistics have several advantages for human sexuality research such as: savings in time and budget; increase in the accuracy of results; and reduction in human errors for data analysis. Rafiee J, Rafiee MA, and Michaelsen D. Female sexual responses using signal processing techniques. J Sex Med 2009;6:3086–3096.