Judit Angster - Academia.edu (original) (raw)
Papers by Judit Angster
Der Abgassimulator des Fraunhofer IBP wurde fur die Nachbildung und Messung von Abgasen aus unter... more Der Abgassimulator des Fraunhofer IBP wurde fur die Nachbildung und Messung von Abgasen aus unterschiedlichen industriellen Prozessen im Rahmen eines von der Deutschen Bundesstiftung Umwelt (DBU) geforderten Projekts entwickelt. Diese innovative Einrichtung ist so konzipiert und flexibel konstruiert, dass vielfaltige Prozessuntersuchungen unter bekannten und reproduzierbaren Bedingungen im Dauerbetrieb durchfuhrbar sind. Der Abgassimulator verfugt uber hochgenaue Messeinrichtungen zur Erfassung von staubund gasformigen Komponenten sowie zur Ermittlung der notigen Abgasparameter (Abgasmassenstrom, Abgastemperatur, Abgasdruck, Feuchtegehalt). Dank der innovativen Bauweise wurde der Abgassimulator fur mehrere Anwendungen wie z. B. zur Entwicklung photoakustischer Feinstaub-Sensorik, zur Untersuchung des Verhaltens der Lambdasonde bei unterschiedlichen Konzentrationen unverbrannter Bestandteile im Abgas und zur Untersuchung der Abscheideleistung von Staubabscheidern und Katalysatoren ei...
Sound generated in a flue organ pipe is susceptible to the voicing adjustment. A small change in ... more Sound generated in a flue organ pipe is susceptible to the voicing adjustment. A small change in the configurations of the flue, lower and upper labiums, etc. often results in a great change in the sound. This research aims to assist the voicing process by clarifying the effect of the adjustment on the physical properties of the air jet emerging from the flue and thus on the output sound. To this end, the numerical simulation of the airflow in the flue pipe and the sound synthesis based on the physical modeling are performed. Two specific adjustments are considered in this paper: the height of the lower labium relative to the languid and the inner geometry of the foot hole.
The photoacoustic (PA) effect, the generation of sound by the absorption of pulsed or modulated l... more The photoacoustic (PA) effect, the generation of sound by the absorption of pulsed or modulated light, has been known since the famous experiments of Alexander Graham Bell in 1880. Scientific and practical applications of the photoacoustic technique have been considerably promoted by the invention of laser, which is an ideal light source for photoacoustics. Recently, photoacoustic detectors play an increasing role in trace gas detection and analysis. The sensitivity of a small, simple and cheap photoacoustic detector is only slightly lower than that of a very sophisticated and expensive optical system equipped with a multipass optical absorption cell and a liquid nitrogen cooled infrared detector.
The functioning of the first type, the flue or labial pipe, was already investigated within previ... more The functioning of the first type, the flue or labial pipe, was already investigated within previous extensive research projects. The second pipe type, the reed pipe, is less often installed in pipe organs, and only little research was done in this field so far. This is why this pipe type is now the focus of research of the working group ‚Musical Acoustics ‘ at the Fraunhofer Institute for Building Physics.
Sound generated in a flue organ pipe is susceptible to the voicing adjustment. A small change in ... more Sound generated in a flue organ pipe is susceptible to the voicing adjustment. A small change in the configurations of the flue, lower and upper labiums, etc. often results in a great change in the sound. This research aims to assist the voicing process by clarifying the effect of the adjustment on the physical properties of the air jet emerging from the flue and thus on the output sound. To this end, the numerical simulation of the airflow in the flue pipe and the sound synthesis based on the physical modeling are performed. Two specific adjustments are considered in this paper: the height of the lower labium relative to the languid and the inner geometry of the foot hole.
The Journal of the Acoustical Society of America, 2021
This paper presents the experimental examination of an alternative lingual organ pipe constructio... more This paper presents the experimental examination of an alternative lingual organ pipe construction that uses a free tongue which, in contrast with traditional lingual organ pipes, operates in a blown open manner. A possible advantage of the construction is that it can enable changing the windchest pressure and thus, achieving an extended dynamic range while keeping a constant pitch. Three experimental pipes with diverse resonator shapes are investigated in various setups. The three pipes also demonstrate the variety of timbres obtainable by different configurations of tongues and resonators. The analysis of the measurement results shows that the pipes exhibit a very good stability of the fundamental frequency and can have a dynamic range of 15 dB. At the same time, the timbre of the sound is found to change significantly as the windchest pressure is increased. Experiments performed with damping the resonator reveal the working principle of the tongue-resonator coupling in the alternative construction. Several sound recordings are presented as multimedia file attachments enabling the subjective comparison of the pipe sounds.
The Journal of the Acoustical Society of America, 2021
This paper presents the experimental examination of an alternative lingual organ pipe constructio... more This paper presents the experimental examination of an alternative lingual organ pipe construction that uses a free tongue which, in contrast with traditional lingual organ pipes, operates in a blown open manner. A possible advantage of the construction is that it can enable changing the windchest pressure and thus, achieving an extended dynamic range while keeping a constant pitch. Three experimental pipes with diverse resonator shapes are investigated in various setups. The three pipes also demonstrate the variety of timbres obtainable by different configurations of tongues and resonators. The analysis of the measurement results shows that the pipes exhibit a very good stability of the fundamental frequency and can have a dynamic range of 15 dB. At the same time, the timbre of the sound is found to change significantly as the windchest pressure is increased. Experiments performed with damping the resonator reveal the working principle of the tongue-resonator coupling in the alternative construction. Several sound recordings are presented as multimedia file attachments enabling the subjective comparison of the pipe sounds.
The Journal of the Acoustical Society of America, 2016
In a traditional pipe organ, the dynamic range of both labial (flue) and lingual (reed) pipe rank... more In a traditional pipe organ, the dynamic range of both labial (flue) and lingual (reed) pipe ranks are strictly limited as each rank is tuned and voiced to a nominal windchest pressure. Changing this pressure not only affects the amplitude of the radiated sound but both the pitch and the timbre of the pipes. A new pipe construction with a blown open free tongue was proposed recently to overcome this limitation. Prototype pipes of the new construction were built and measurements were carried out on them at different blowing pressures. It was found that the new construction provides a pleasing stability of the pitch and a broad range of playable amplitudes; however, the timbre of the pipes changes significantly with the blowing pressure. To improve the design in the latter aspect, a physical model of the pipes needs to be established first. In this contribution the sound generation of the experimental pipes is simulated by time domain computations. The resonator and its interaction with the vibration of the...
The Journal of the Acoustical Society of America, 2016
In a traditional pipe organ, the dynamic range of both labial (flue) and lingual (reed) pipe rank... more In a traditional pipe organ, the dynamic range of both labial (flue) and lingual (reed) pipe ranks are strictly limited as each rank is tuned and voiced to a nominal windchest pressure. Changing this pressure not only affects the amplitude of the radiated sound but both the pitch and the timbre of the pipes. A new pipe construction with a blown open free tongue was proposed recently to overcome this limitation. Prototype pipes of the new construction were built and measurements were carried out on them at different blowing pressures. It was found that the new construction provides a pleasing stability of the pitch and a broad range of playable amplitudes; however, the timbre of the pipes changes significantly with the blowing pressure. To improve the design in the latter aspect, a physical model of the pipes needs to be established first. In this contribution the sound generation of the experimental pipes is simulated by time domain computations. The resonator and its interaction with the vibration of the...
International Journal of Thermophysics, 2015
In this article, a photothermal technique is presented to detect carbon nanoparticles in suspensi... more In this article, a photothermal technique is presented to detect carbon nanoparticles in suspension and to determine their concentration using the photothermal lens effect and the photothermal beam deflection. Both methods are well researched and described in the corresponding literature. The experimental setup consists of an excitation and a probe laser, and optical devices for beam guidance and signal detection. First, an optical setup to generate both effects in a suspension simultaneously is described. To detect the beam deflection and the beam expansion of the probe beam, different optical detectors were applied; moreover, a graphical CMOS-camera-based method was developed. The dependence of the photothermal effect on the absorption of the pump laser beam is discussed, particularly by varying the concentration of carbon nanoparticles in suspension. It is shown that the absorption of the pump beam and thus the photothermal effects can be modified by changing the concentration of carbon nanoparticles. The measurements with this system are showing that, especially with the graphical method, a determination of the concentration in the low ng$$\cdot ·ml$$^{-1}$$-1 range is possible.
The Journal of the Acoustical Society of America, 2021
The Journal of the Acoustical Society of America, 2016
Within the framework of a European research project exciting new results have been achieved recen... more Within the framework of a European research project exciting new results have been achieved recently in the research of lingual organ pipes. The main objectives of the project are to solve practical problems of the dimensioning of reed organ pipes, to develop innovative methods and software for helping the sound design work of organ builder enterprises. A better understanding of the role of the shallot and resonator on the attack and the timbre of reed pipes is necessary for this reason. Visualization of reed motion by high speed camera and measurements of reed velocity, wind pressure in the boot and shallot, and sound pressure in the shallot and at the end of the resonator have revealed interesting details about the very complex process of sound generation of lingual organ pipes. These experiments have been carried out in close cooperation with the participating organ builder firms. As examples, a few results of the measurements of Crumhorn and Vox Humana pipes are presented. These results, combined with...
International Journal of Thermophysics, 2015
The photoacoustic effect has been studied intensively using light sources emitting in the infrare... more The photoacoustic effect has been studied intensively using light sources emitting in the infrared (IR) region. Corresponding photons lead to excitations of vibrational–rotational energy levels. Subsequent de-excitations by collisions with the surrounding molecules can increase the translational energy of these molecules. Consequently, by irradiating a gas sample with amplitude- or wavelength-modulated light, an acoustic wave can be created and recorded by means of microphones. In the case of light absorption in the ultraviolet (UV) region, however, the photon energy is too large for the before-mentioned transitions. Instead, photon absorption can induce electronic transitions or even molecule dissociation. While experiments reveal that these effects lead to a photoacoustic signal as well (see, e.g. Cvijin et al. in Appl Spectrosc 42:770, 1988; Dóka et al. in Appl Spectrosc 54:1405, 2000; Gondal and Mastromarino in Appl Opt 40:2010, 2001; Böttger et al. in Appl Phys B 113:227, 2013), investigations concerning the reason have been hardly published to date. By means of a 266 nm UV laser and an IR optical parametric oscillator (OPO) setup, photoacoustic measurements were carried out with a synthetic air–acetone gas mixture. In this paper, both measurements are compared with each other and the fundamental processes of photoacoustic signal production in the UV region are discussed.
As a traditional Chinese mouth organ with lingual pipes, Sheng pipes are arranged in a round bund... more As a traditional Chinese mouth organ with lingual pipes, Sheng pipes are arranged in a round bundle. Therefore Sheng has pipe-dependent sound orientation. To get a better understanding on its sound radiation pattern, a B&K source identification system is used to measure the near field hologram of Sheng. Two measurements are presented in this paper. The first one investigates the active intensity distribution of 4 selected pipes as individual, while the second one measures the same pipes but as a component of the entire Sheng. Comparison of the active intensity distribution between the individual Sheng pipes and the labial organ pipes are also presented to explaining the result of the measurements.
Der Abgassimulator des Fraunhofer IBP wurde fur die Nachbildung und Messung von Abgasen aus unter... more Der Abgassimulator des Fraunhofer IBP wurde fur die Nachbildung und Messung von Abgasen aus unterschiedlichen industriellen Prozessen im Rahmen eines von der Deutschen Bundesstiftung Umwelt (DBU) geforderten Projekts entwickelt. Diese innovative Einrichtung ist so konzipiert und flexibel konstruiert, dass vielfaltige Prozessuntersuchungen unter bekannten und reproduzierbaren Bedingungen im Dauerbetrieb durchfuhrbar sind. Der Abgassimulator verfugt uber hochgenaue Messeinrichtungen zur Erfassung von staubund gasformigen Komponenten sowie zur Ermittlung der notigen Abgasparameter (Abgasmassenstrom, Abgastemperatur, Abgasdruck, Feuchtegehalt). Dank der innovativen Bauweise wurde der Abgassimulator fur mehrere Anwendungen wie z. B. zur Entwicklung photoakustischer Feinstaub-Sensorik, zur Untersuchung des Verhaltens der Lambdasonde bei unterschiedlichen Konzentrationen unverbrannter Bestandteile im Abgas und zur Untersuchung der Abscheideleistung von Staubabscheidern und Katalysatoren ei...
Sound generated in a flue organ pipe is susceptible to the voicing adjustment. A small change in ... more Sound generated in a flue organ pipe is susceptible to the voicing adjustment. A small change in the configurations of the flue, lower and upper labiums, etc. often results in a great change in the sound. This research aims to assist the voicing process by clarifying the effect of the adjustment on the physical properties of the air jet emerging from the flue and thus on the output sound. To this end, the numerical simulation of the airflow in the flue pipe and the sound synthesis based on the physical modeling are performed. Two specific adjustments are considered in this paper: the height of the lower labium relative to the languid and the inner geometry of the foot hole.
The photoacoustic (PA) effect, the generation of sound by the absorption of pulsed or modulated l... more The photoacoustic (PA) effect, the generation of sound by the absorption of pulsed or modulated light, has been known since the famous experiments of Alexander Graham Bell in 1880. Scientific and practical applications of the photoacoustic technique have been considerably promoted by the invention of laser, which is an ideal light source for photoacoustics. Recently, photoacoustic detectors play an increasing role in trace gas detection and analysis. The sensitivity of a small, simple and cheap photoacoustic detector is only slightly lower than that of a very sophisticated and expensive optical system equipped with a multipass optical absorption cell and a liquid nitrogen cooled infrared detector.
The functioning of the first type, the flue or labial pipe, was already investigated within previ... more The functioning of the first type, the flue or labial pipe, was already investigated within previous extensive research projects. The second pipe type, the reed pipe, is less often installed in pipe organs, and only little research was done in this field so far. This is why this pipe type is now the focus of research of the working group ‚Musical Acoustics ‘ at the Fraunhofer Institute for Building Physics.
Sound generated in a flue organ pipe is susceptible to the voicing adjustment. A small change in ... more Sound generated in a flue organ pipe is susceptible to the voicing adjustment. A small change in the configurations of the flue, lower and upper labiums, etc. often results in a great change in the sound. This research aims to assist the voicing process by clarifying the effect of the adjustment on the physical properties of the air jet emerging from the flue and thus on the output sound. To this end, the numerical simulation of the airflow in the flue pipe and the sound synthesis based on the physical modeling are performed. Two specific adjustments are considered in this paper: the height of the lower labium relative to the languid and the inner geometry of the foot hole.
The Journal of the Acoustical Society of America, 2021
This paper presents the experimental examination of an alternative lingual organ pipe constructio... more This paper presents the experimental examination of an alternative lingual organ pipe construction that uses a free tongue which, in contrast with traditional lingual organ pipes, operates in a blown open manner. A possible advantage of the construction is that it can enable changing the windchest pressure and thus, achieving an extended dynamic range while keeping a constant pitch. Three experimental pipes with diverse resonator shapes are investigated in various setups. The three pipes also demonstrate the variety of timbres obtainable by different configurations of tongues and resonators. The analysis of the measurement results shows that the pipes exhibit a very good stability of the fundamental frequency and can have a dynamic range of 15 dB. At the same time, the timbre of the sound is found to change significantly as the windchest pressure is increased. Experiments performed with damping the resonator reveal the working principle of the tongue-resonator coupling in the alternative construction. Several sound recordings are presented as multimedia file attachments enabling the subjective comparison of the pipe sounds.
The Journal of the Acoustical Society of America, 2021
This paper presents the experimental examination of an alternative lingual organ pipe constructio... more This paper presents the experimental examination of an alternative lingual organ pipe construction that uses a free tongue which, in contrast with traditional lingual organ pipes, operates in a blown open manner. A possible advantage of the construction is that it can enable changing the windchest pressure and thus, achieving an extended dynamic range while keeping a constant pitch. Three experimental pipes with diverse resonator shapes are investigated in various setups. The three pipes also demonstrate the variety of timbres obtainable by different configurations of tongues and resonators. The analysis of the measurement results shows that the pipes exhibit a very good stability of the fundamental frequency and can have a dynamic range of 15 dB. At the same time, the timbre of the sound is found to change significantly as the windchest pressure is increased. Experiments performed with damping the resonator reveal the working principle of the tongue-resonator coupling in the alternative construction. Several sound recordings are presented as multimedia file attachments enabling the subjective comparison of the pipe sounds.
The Journal of the Acoustical Society of America, 2016
In a traditional pipe organ, the dynamic range of both labial (flue) and lingual (reed) pipe rank... more In a traditional pipe organ, the dynamic range of both labial (flue) and lingual (reed) pipe ranks are strictly limited as each rank is tuned and voiced to a nominal windchest pressure. Changing this pressure not only affects the amplitude of the radiated sound but both the pitch and the timbre of the pipes. A new pipe construction with a blown open free tongue was proposed recently to overcome this limitation. Prototype pipes of the new construction were built and measurements were carried out on them at different blowing pressures. It was found that the new construction provides a pleasing stability of the pitch and a broad range of playable amplitudes; however, the timbre of the pipes changes significantly with the blowing pressure. To improve the design in the latter aspect, a physical model of the pipes needs to be established first. In this contribution the sound generation of the experimental pipes is simulated by time domain computations. The resonator and its interaction with the vibration of the...
The Journal of the Acoustical Society of America, 2016
In a traditional pipe organ, the dynamic range of both labial (flue) and lingual (reed) pipe rank... more In a traditional pipe organ, the dynamic range of both labial (flue) and lingual (reed) pipe ranks are strictly limited as each rank is tuned and voiced to a nominal windchest pressure. Changing this pressure not only affects the amplitude of the radiated sound but both the pitch and the timbre of the pipes. A new pipe construction with a blown open free tongue was proposed recently to overcome this limitation. Prototype pipes of the new construction were built and measurements were carried out on them at different blowing pressures. It was found that the new construction provides a pleasing stability of the pitch and a broad range of playable amplitudes; however, the timbre of the pipes changes significantly with the blowing pressure. To improve the design in the latter aspect, a physical model of the pipes needs to be established first. In this contribution the sound generation of the experimental pipes is simulated by time domain computations. The resonator and its interaction with the vibration of the...
International Journal of Thermophysics, 2015
In this article, a photothermal technique is presented to detect carbon nanoparticles in suspensi... more In this article, a photothermal technique is presented to detect carbon nanoparticles in suspension and to determine their concentration using the photothermal lens effect and the photothermal beam deflection. Both methods are well researched and described in the corresponding literature. The experimental setup consists of an excitation and a probe laser, and optical devices for beam guidance and signal detection. First, an optical setup to generate both effects in a suspension simultaneously is described. To detect the beam deflection and the beam expansion of the probe beam, different optical detectors were applied; moreover, a graphical CMOS-camera-based method was developed. The dependence of the photothermal effect on the absorption of the pump laser beam is discussed, particularly by varying the concentration of carbon nanoparticles in suspension. It is shown that the absorption of the pump beam and thus the photothermal effects can be modified by changing the concentration of carbon nanoparticles. The measurements with this system are showing that, especially with the graphical method, a determination of the concentration in the low ng$$\cdot ·ml$$^{-1}$$-1 range is possible.
The Journal of the Acoustical Society of America, 2021
The Journal of the Acoustical Society of America, 2016
Within the framework of a European research project exciting new results have been achieved recen... more Within the framework of a European research project exciting new results have been achieved recently in the research of lingual organ pipes. The main objectives of the project are to solve practical problems of the dimensioning of reed organ pipes, to develop innovative methods and software for helping the sound design work of organ builder enterprises. A better understanding of the role of the shallot and resonator on the attack and the timbre of reed pipes is necessary for this reason. Visualization of reed motion by high speed camera and measurements of reed velocity, wind pressure in the boot and shallot, and sound pressure in the shallot and at the end of the resonator have revealed interesting details about the very complex process of sound generation of lingual organ pipes. These experiments have been carried out in close cooperation with the participating organ builder firms. As examples, a few results of the measurements of Crumhorn and Vox Humana pipes are presented. These results, combined with...
International Journal of Thermophysics, 2015
The photoacoustic effect has been studied intensively using light sources emitting in the infrare... more The photoacoustic effect has been studied intensively using light sources emitting in the infrared (IR) region. Corresponding photons lead to excitations of vibrational–rotational energy levels. Subsequent de-excitations by collisions with the surrounding molecules can increase the translational energy of these molecules. Consequently, by irradiating a gas sample with amplitude- or wavelength-modulated light, an acoustic wave can be created and recorded by means of microphones. In the case of light absorption in the ultraviolet (UV) region, however, the photon energy is too large for the before-mentioned transitions. Instead, photon absorption can induce electronic transitions or even molecule dissociation. While experiments reveal that these effects lead to a photoacoustic signal as well (see, e.g. Cvijin et al. in Appl Spectrosc 42:770, 1988; Dóka et al. in Appl Spectrosc 54:1405, 2000; Gondal and Mastromarino in Appl Opt 40:2010, 2001; Böttger et al. in Appl Phys B 113:227, 2013), investigations concerning the reason have been hardly published to date. By means of a 266 nm UV laser and an IR optical parametric oscillator (OPO) setup, photoacoustic measurements were carried out with a synthetic air–acetone gas mixture. In this paper, both measurements are compared with each other and the fundamental processes of photoacoustic signal production in the UV region are discussed.
As a traditional Chinese mouth organ with lingual pipes, Sheng pipes are arranged in a round bund... more As a traditional Chinese mouth organ with lingual pipes, Sheng pipes are arranged in a round bundle. Therefore Sheng has pipe-dependent sound orientation. To get a better understanding on its sound radiation pattern, a B&K source identification system is used to measure the near field hologram of Sheng. Two measurements are presented in this paper. The first one investigates the active intensity distribution of 4 selected pipes as individual, while the second one measures the same pipes but as a component of the entire Sheng. Comparison of the active intensity distribution between the individual Sheng pipes and the labial organ pipes are also presented to explaining the result of the measurements.