Windows are a weakness in building facade sound transmission loss (STL). This coupled with the detrimental effects of excessive noise exposure on human health including: annoyance, sleep deprivation, hearing impairment and heart disease, is the motivation for this investigation of the STL improvements active noise control (ANC) of windows can provide. Window speaker development, ANC window experiments and analytical modelling of ANC windows were investigated. Five different window speaker constructions were characterised then compared with a previously developed window speaker. ANC window testing used three different ANC configurations and was performed in two different environments, one with a reverberant receiving room, and the other with an anechoic receiving room. Optimisation of ANC systems with particular control source locations was the aim of the modelling. This enabled comparison with the ANC window tests and would aid in further development of ANC windows. Window speaker constructions were characterised by sound pressure level (SPL) measurements performed in an anechoic room. These measurements were made in a way that enabled comparison with the previously developed window speaker. Total sound energy reduction calculations were used to determine the relative performance of the tested ANC windows. An STL model, based on a modal panel vibration model, was initially created and verified against published STL data before it was expanded to include ANC control sources. The model was used to simulate the performed anechoic environment tests and an ideal ANC case.

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Air-borne ultrasonic transducers are optimised to achieve a maximal sound pressure in a frequency range around 100 kHz. Moreover, the radiation of a high acoustic power is desired, which requires a large transducer area. Within this dissertation the ultrasonic transducers are, therefore, optimised to operate in the resonance mode. Using this operating point the maximal force is fed into the transducer while it is charged with the lowest loss possible. Many applications of air-borne ultrasound need a sufficient bandwidth in addition to a high sound pressure, that s why the swinging mass of the transducer has to be minimised. For these reasons, air-borne capacitive and piezoelectric film transducers take centre stage of these examinations. New network models of the stripe membrane and the pre-stressed stripe plate are derived to optimise these ultrasonic transducers. Besides its mechanical tension and its bending stiffness, the new network model of the pre-stressed and pressure loaded stripe plate takes also the stiffness caused by the shape of the plate into account. The examined transducers achive a maximal piston velocity around 1 m/s. / Ultraschallwandler für Anwendungen in Luft werden zur Bereitstellung eines maximalen Schalldrucks im Frequenzbereich um 100 kHz optimiert. Sie sollen außerdem die Abstrahlung einer großen Schallleistung zulassen, was eine große Wandlerfläche voraussetzt. Deshalb werden in dieser Arbeit die Ultraschallsender für den Resonanzbetrieb optimiert, wo man die maximale Krafteinspeisung bei minimalen Verlusten einstellt. Viele Anwendungen von Ultraschall in Luft benötigen neben einem hohen Schalldruckpegel auch eine ausreichende Bandbreite, wozu die schwingende Masse der Wandler zu minimieren ist. Deshalb stehen kapazitive und piezoelektrische Folienwandler im Resonanzbetrieb im Vordergrund der Untersuchungen. Zur Optimierung dieser Ultraschallsender werden die Netzwerkmodelle der Streifenmembran und der gespannten Streifenplatte abgeleitet. Neben der mechanischen Spannung und der Biegesteifigkeit berücksichtigt das Netzwerkmodell der gespannten und statisch druckbelasteten Streifenplatte die Formversteifung. Die untersuchten Wandler erreichen eine maximale Kolbenschnelle um 1 m/s.

The growth of sensors and sensing technologies have made significant impact in our day-to-day life. The five principle sensory organs of our body should perform effectively, so that we can lead a good healthy life. Apart from these natural sensors, there are man-made sensors that helps us to cope with diseases, organ failure etc. and enable us to lead a normal life. In recent years, with the prevalence of new kind of diseases, the need for new type of biomedical sensors is becoming very important. As a result, sensors used for biomedical applications have become an emerging technology and rapidly growing field of research. The aim of the present thesis work is to use the piezoelectric property of Polyvinylidene Fluoride (PVDF) film for the development of biomedical sensor and studying its application for human respiration/breathing related abnormalities. PVDF nasal sensor was designed in cantilever configuration and detailed theoretical analysis of the same was performed. Based on theoretical and experimental results, the PVDF nasal sensor dimensions were optimized. Suitable signal conditioning circuitry was designed and a measurement system for biomedical application was developed. The developed PVDF nasal sensor was calibrated using MEMS low-pressure sensor. The PVDF nasal sensor system has been applied in different biomedical applications namely, (i) to monitor human respiration pattern, (ii) to identify different Respiration Rates (RR), (iii) to evaluate Deviated Nasal Septum (DNS) in comparison with other objective method and, (vi) to clinically investigate nasal obstruction in comparison with subjective method. The thesis is divided into seven chapters. Chapter 1 This chapter gives a general introduction about biomedical sensors, piezoelectric sensing principle and PVDF polymer films along with the relevant literature survey. The brief introduction as well as literature survey of techniques used to monitor human respiration and to measure nasal obstruction is also included in this chapter. Chapter 2 This chapter gives details about the design of the PVDF nasal sensor in the cantilever configuration for sensing nasal airflow along with the relevant theoretical equations. Also, the details on the optimization of the PVDF nasal sensor dimensions based on the theoretical and experimental analysis are presented. Chapter 3 This chapter reports the designing of the necessary signal conditioning hardware along with the data acquisition unit for the PVDF nasal sensor. The signal conditioning hardware unit made consists of charge amplifier, low-pass filter and an amplifier. Besides, a complete measurement system for biomedical application was developed using PVDF nasal sensor and its merits and demerits were discussed. Chapter 4 In this chapter, an experimental set-up for measuring human respiration/breathing pressure using water U-tube manometer has been described. Also, the calibration procedure followed for the developed PVDF nasal sensor using a Micro Electro Mechanical Systems(MEMS) low pressure sensor is reported. Apart from these, the details on the measurement of deflection of the PVDF cantilever sensing element using laser displacement setup are provided. In addition, the PVDF nasal sensor was also calibrated for various air flow rates. At the end, a study has been reported on optimizing the position the PVDF nasal sensor with respect to human nose. Chapter 5 This chapter is divided into two sections, Section 5.1: This section describes the applicability of the PVDF nasal sensor using its piezoelectric property to monitor the human respiration pattern of each nostril simultaneously. The results of the PVDF nasal sensor have also been evaluated by comparing with Respiratory Inductive Plethysmograph(RIP) technique in normal subjects. Section 5.2: In this section, PVDF nasal sensor, RIP and Nasal Prongs (NP) techniques were used to measure the RR of healthy adults. The aim here was to evaluate the presently developed PVDF nasal sensor for identifying different RR compared to „Gold standard‟ RIP and NP methods. Chapter 6 This chapter is divided into two sections. Section 6.1: This section reports about the utilization of the developed PVDF nasal sensor for clinical application on the patient population. For this purpose, the performance of the PVDF nasal sensor measurements has been compared with the Peak Nasal Inspiratory Flow(PNIF) objective technique and visual analog scale (VAS). Section 6.2: This section describes about the use of PVDF nasal sensor system to measure nasal obstruction caused due to DNS objectively. Further, the results of the PVDF nasal sensor were compared with subjective techniques namely, VAS and clinician scale in patients and control group. Chapter 7 This chapter is composed of two sections. Section 7.1: This section summarizes the salient features of the work presented in this thesis. Section 7.2: This section reports a scope for carrying out further work.

Air-borne ultrasonic transducers are optimised to achieve a maximal sound pressure in a frequency range around 100 kHz. Moreover, the radiation of a high acoustic power is desired, which requires a large transducer area. Within this dissertation the ultrasonic transducers are, therefore, optimised to operate in the resonance mode. Using this operating point the maximal force is fed into the transducer while it is charged with the lowest loss possible. Many applications of air-borne ultrasound need a sufficient bandwidth in addition to a high sound pressure, that s why the swinging mass of the transducer has to be minimised. For these reasons, air-borne capacitive and piezoelectric film transducers take centre stage of these examinations. New network models of the stripe membrane and the pre-stressed stripe plate are derived to optimise these ultrasonic transducers. Besides its mechanical tension and its bending stiffness, the new network model of the pre-stressed and pressure loaded stripe plate takes also the stiffness caused by the shape of the plate into account. The examined transducers achive a maximal piston velocity around 1 m/s. / Ultraschallwandler für Anwendungen in Luft werden zur Bereitstellung eines maximalen Schalldrucks im Frequenzbereich um 100 kHz optimiert. Sie sollen außerdem die Abstrahlung einer großen Schallleistung zulassen, was eine große Wandlerfläche voraussetzt. Deshalb werden in dieser Arbeit die Ultraschallsender für den Resonanzbetrieb optimiert, wo man die maximale Krafteinspeisung bei minimalen Verlusten einstellt. Viele Anwendungen von Ultraschall in Luft benötigen neben einem hohen Schalldruckpegel auch eine ausreichende Bandbreite, wozu die schwingende Masse der Wandler zu minimieren ist. Deshalb stehen kapazitive und piezoelektrische Folienwandler im Resonanzbetrieb im Vordergrund der Untersuchungen. Zur Optimierung dieser Ultraschallsender werden die Netzwerkmodelle der Streifenmembran und der gespannten Streifenplatte abgeleitet. Neben der mechanischen Spannung und der Biegesteifigkeit berücksichtigt das Netzwerkmodell der gespannten und statisch druckbelasteten Streifenplatte die Formversteifung. Die untersuchten Wandler erreichen eine maximale Kolbenschnelle um 1 m/s.