Ajit Kolla

Publication Date


Document Type


First Advisor

Liu, Lichuan, 1945-

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Electrical Engineering


Incubators (Pediatrics); Active noise and vibration control; Signal processing--Digital techniques


Noise problems have become more and more severe with an increase in use of medical equipment such as ventilators, oximeters, alarms, etc in Neonatal Intensive Care Unit (NICU). These have a severe impact on the physiological and behavioral state of the infants. The concept of a feedforward active noise control (ANC) system using the filtered-x least mean square (FxLMS) algorithm is applied to reduce the noise levels in NICU. In this thesis, various key variables related to the ANC sysrem for infant incubator are assessed in order to evaluate their effect on the performance of the system. The size of quiet zone generated inside the incubator based on the best combination of key variables is discussed. For this purpose, a three-dimensional (3-D) test fixture that enables uniformly spaced test points is used to measure the amount of noise attenuation in real-time. While the infant is present in the incubator, it is deprived of the parent's attachment. Also it is known to create increased stress and trauma for the mother when she is not able to bond with the newborn. Another main contribution of this thesis is to establish a two way communication between the parent and the baby while the ANC is in operation. It is to be noted that there is some amount of residual noise still present even after the ANC is implemented. The infant sound together with this background noise is transmitted and received by the parent thereby creating difficulty for the parent to interpret the baby sound. This thesis also mentions speech enhancement (SE) techniques that can be implemented to enhance the infant's sound. Computer simulations are performed using two SE techniques and their performance is compared.


Advisors: Lichuan Liu.||Committee members: Martin Kocanda; Mansour Tahernezhadi.||Includes bibliographical references.||Includes illustrations.


ix, 100 pages




Northern Illinois University

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