Open Access
Influence of recording technology on the determination of binaural psychoacoustic indicators in soundscape investigations
(Institute of Noise Control Engineering, 2019) San Martín Murugarren, Ricardo; Arana Burgui, Miguel; Ezcurra Guisasola, María Amaya; Valencia Leoz, Ana; Ciencias; Zientziak
The evaluation of soundscapes is mainly carried out through field surveys, using soundwalking methodologies. Through rating scales and annotation of comments, the experiences and expectations of the participants are collected. Acoustic and psychoacoustic indicators are also reported to achieve a complete description of the acoustic environment. Binaural measurement systems should be used for registration in order to consider the way in which humans perceive the acoustic environment. Artificial heads or in-ear binaural microphones are the usual devices for this purpose. Further recording technology such as sound field microphones or microphone arrays are also used in soundscape investigations. These methods can provide a higher level of immersion in a later reproduction of the recorded soundscape through multi-channel setups. However, in contrast to direct binaural recordings, the determination of binaural psychoacoustic indicators requires to perform binaural synthesis by means of Head-Related Transfer Functions and signal processing. In this communication, the influence of different recording devices on obtaining psychoacoustic indicators such as binaural loudness and sharpness is analysed.
Open Access
Aprendizaje basado en casos en la enseñanza de la Acústica Arquitectónica: acondicionamiento acústico del gimnasio de una escuela para utilizarlo como sala de conferencias
(Sociedade Portuguesa de Acústica, 2024) San Martín Murugarren, Ricardo; Arana Burgui, Miguel; Eguinoa Cabrito, Rubén; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
El Aprendizaje Basado en Casos (Case-Based Learning, CBL) es una de las metodologías activas de aprendizaje cooperativo más empleadas, sobre todo en escuelas de negocios o estudios de derecho, pero también en últimos cursos de ingeniería. Consiste en crear situaciones similares a las que los estudiantes se enfrentarán en su vida profesional al finalizar sus estudios. Esta comunicación presenta una experiencia desarrollada en la asignatura Acústica Arquitectónica del Grado en Ingeniería en Tecnologías de Telecomunicación de la Universidad Pública de Navarra. El caso diseñado recrea una de las actividades profesionales a las que se enfrenta habitualmente un ingeniero acústico: el acondicionamiento de un recinto por deficiencia acústica, reforma o cambio de uso. Se describen aspectos curriculares, planificación, materiales disponibles, método de evaluación y resultados obtenidos, junto con la valoración tanto del profesorado como del alumnado.
Open Access
Experimental evaluation of distortion in amplitude modulation techniques for parametric loudspeakers
(MDPI, 2020) San Martín Murugarren, Ricardo; Tello Santacana, Pablo; Valencia Leoz, Ana; Marzo Pérez, Asier; Institute for Advanced Materials and Mathematics - INAMAT2; Institute of Smart Cities - ISC; Gobierno de Navarra / Nafarroako Gobernua
Parametric loudspeakers can generate a highly directional beam of sound, having applications in targeted audio delivery. Audible sound modulated into an ultrasonic carrier will get self-demodulated along the highly directive beam due to the non-linearity of air. This non-linear demodularization should be compensated to reduce audio distortion, different amplitude modulation techniques have been developed during the last years. However, some studies are only theoretical whereas others do not analyze the audio distortion in depth. Here, we present a detailed experimental evaluation of the frequency response, harmonic distortion and intermodulation distortion for various amplitude modulation techniques applied with different indices of modulation. We used a simple method to measure the audible signal that prevents the saturation of the microphones when the high levels of the ultrasonic carrier are present. This work could be useful for selecting predistortion techniques and indices of modulation for regular parametric arrays.
Open Access
Measurement and analysis of mechanical noise in wind turbines
(Institute of Acoustics, 2016) Arana Burgui, Miguel; Machín Mindán, Jorge; San Martín Murugarren, Ricardo; Ciencias; Zientziak
Open Access
Acoustic and psychoacoustic levels from an internal combustion engine fueled by hydrogen vs. gasoline
(Elsevier, 2022) Arana Burgui, Miguel; San Martín Murugarren, Ricardo; Urroz Unzueta, José Carlos; Diéguez Elizondo, Pedro; Gandía Pascual, Luis; Zientziak; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Ingeniería; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Whereas noise generated by road traffic is an important factor in urban pollution, little attention has been paid to this issue in the field of hydrogen-fueled vehicles. The objective of this study is to analyze the influence of the type of fuel (gasoline or hydrogen) on the sound levels produced by a vehicle with an internal combustion engine. A Volkswagen Polo 1.4 vehicle adapted for its bi-fuel hydrogen-gasoline operation has been used. Tests were carried out with the vehicle when stationary to eliminate rolling and aerodynamic noise. Acoustics and psychoacoustics levels were measured both inside and outside the vehicle. A slight increase in the noise level has only been found outside when using hydrogen as fuel, compared to gasoline. The increase is statistically significant, can be quantified between 1.1 and 1.7 dBA and is mainly due to an intensification of the 500 Hz band. Loudness is also higher outside the vehicle (between 2 and 4 sones) when the fuel is hydrogen. Differences in sharpness and roughness values are lower than the just-noticeable difference (JND) values of the parameters. Higher noise levels produced by hydrogen can be attributed to its higher reactivity compared to gasoline.
Open Access
Subjective evaluation of the localization performance of the spherical wavelet format compared to ambisonics
(IEEE, 2021) Eguinoa Cabrito, Rubén; San Martín Murugarren, Ricardo; Arteaga, Daniel; Scaini, Davide; Ciencias; Zientziak
A common goal of most spatial audio techniques is to reproduce the precise location and size of sound sources. Ambisonics is a well-established spatial audio technique that renders sound sources with increasing accuracy as the Ambisonics’ order increases. Recently, a novel spatial audio format that replaces spherical harmonics with a set of functions based on wavelets has been proposed. The Spherical Wavelet Format (SWF) aims to improve Ambisonics localization, especially at low orders. This study investigates the perceptual spatial properties of both techniques by means of a set of MUSHRA tests.
Open Access
Uncertainties caused by source directivity in room-acoustic investigations
(Acoustical Society of America (ASA), 2008) San Martín Murugarren, Ricardo; Arana Burgui, Miguel; Física; Fisika
Although deviations in the measurement of acoustic parameters should be lower than the subjectively perceivable change in the corresponding parameter measured, this study reflects that directionality of sound sources could cause wide audience areas to break away from this criterion at high frequencies, even when using dodecahedron loudspeakers which meet the requirements of the ISO 3382 standard. The directivity of four different acoustic sources was measured and the influence of its accurate orientation spatially quantified in five enclosures for speech and music. By means of simulation software, the number of receivers affected by uncertainties greater than difference limens was established.
Open Access
Localization of sound sources in binaural reproduction of first and third order ambisonics
(Poznan University of Technology, 2022) Sagasti, Amaia; Pietrzak, Agnieszka Paula; San Martín Murugarren, Ricardo; Eguinoa Cabrito, Rubén; Ciencias; Zientziak
The use of higher-order ambisonics in spatial sound recordings makes it possible to increase the accuracy of recording information about the direction from which the sound comes to the listener. However, with binaural ambisonic sound reproduction, the listener's ability to locate the sound source accurately may be limited. This paper presents a comparison of the listener's ability to locate a sound source during binaural listening to recordings made with first and third order ambisonic microphones. The analysis was carried out for two types of signal: pink noise and ringing sound. The analysis of localization errors depending on the ambisonics order, azimuth and elevation angles as well as the type of signal is presented. The obtained data indicate that in binaural reproduction of the ambisonic sound the localization errors in the azimuth plane were smaller for the third order ambisonics, compared to the first order. In the elevation plane both for first and third order the errors were significant.
Open Access
Strategic noise map of a major road carried out with two environmental prediction software packages
(Springer Netherlands, 2010) Arana Burgui, Miguel; San Martín Murugarren, Ricardo; San Martín Erviti, María Luisa; Aramendía Santamaría, Emilio; Física; Fisika
The main objective of this study is to analyze the differences found in the results of noise mapping using two of the most popular software techniques for the prediction of environmental noise. The location selected to conduct the comparative study is an area encompassed by the ring road that surrounds the city of Pamplona and on a grid, with a total of 6 × 105 points, approximately. In fact, and as the Environmental Noise Directive points out, it is a major road designated by a Member State (Spain). Configuration of the calculation parameters (discretization of the sources, ground absorption, reflection order, etc.) was as equivalent as possible as far as programs allow. In spite of that, a great number of differences appear in the findings. Although in 95.5% of the points the difference in the noise level calculated from the two programs was less than 3 dB, this general statistic result concealed some great differences. These are due to the various algorithms that programs implement to evaluate noise levels. Most differences pertain to highly screened receivers or remote ones. In the former, the algorithm of visibility is the main cause of such differences. In the latter, differences are mainly brought about by a different implementation of the propagation under homogeneous and favorable atmospheric conditions from both software systems.
Open Access
Diversos errores y dificultades en la enseñanza-aprendizaje de la acústica física y algunas propuestas de mejora
(Sociedade Portuguesa de Acústica, 2024) Arana Burgui, Miguel; San Martín Murugarren, Ricardo; Eguinoa Cabrito, Rubén; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Tras más de dos décadas de enseñanza de la acústica en primeros cursos universitarios, hemos observado algunas de las principales dificultades que los alumnos muestran en la comprensión del fenómeno acústico, en sus diferentes campos. Las podemos agrupar en tres categorías. En primer lugar, la dificultad de entender el modelo físico al que se aplican las ecuaciones, medio continuo frente a medio discreto, modificando drásticamente el concepto de ‘partícula’ que siempre han utilizado en la mecánica del punto material. En segundo lugar, la dificultad de diseñar e implementar prácticas experimentales que ayuden a ‘visualizar’ y ‘medir’ las magnitudes acústicas involucradas. Finalmente, la asimilación del cambio de la herramienta matemática que se suele utilizar (notación compleja frente a real), a la cual no se le suele dedicar apenas una justificación clara en los libros de texto. En este trabajo se discuten estos aspectos. Mostraremos los principales errores conceptuales detectados en las pruebas de evaluación y se proponen varias sugerencias que, creemos, pueden ayudar a los docentes de esta materia para intentar mitigar las deficiencias detectadas y mejorar el proceso de aprendizaje de la acústica en nuestros grados universitarios.