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
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
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
Proyecto JAULAB, más allá del aula
(Sociedad Española de Acústica, 2022) San Martín Murugarren, Ricardo; Eguinoa Cabrito, Rubén; Beunza, A.; Arana Burgui, Miguel; Ciencias; Zientziak; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
El proyecto JAULAB surge desde el grupo de Acústica de la UPNA con el objetivo de, a través del arte, acercar el trabajo realizado en el Laboratorio de Acústica a espacios menos habituados al lenguaje científico y tecnológico. Para ello, se propuso a artistas de diferentes disciplinas la creación de una instalación sonora para experimentar con escenas sonoras en 3D. Se contactó con el Departamento de Escultura de la Escuela de Arte y Superior de Diseño de Pamplona, que se hizo cargo del diseño de la estructura principal. La estructura se construyó en la Fundación Elkarte, un centro que tiene como objetivo formar a colectivos de reinserción social en el ámbito de la soldadura. Asimismo, con la colaboración del grupo UpnaLab que fomenta la cultura Maker, se diseñaron e imprimieron los altavoces para la instalación. Los usuarios finales de la instalación pueden introducirse en una esfera de 3 metros de diámetro y son rodeados por 24 altavoces independientes que generan audio en forma de contenido sonoro personalizado, escalable, inmersivo e interactivo.
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.
Open Access
People exposed to traffic noise in european agglomerations from noise maps: a critical review
(De Gruyter, 2014) Arana Burgui, Miguel; San Martín Murugarren, Ricardo; Salinas Hilburg, Juan Carlos; Física; Fisika
Two of the main objectives of the European Directive on environmental noise are, firstly, to unify acoustic indices for assessing environmental noise and, secondly, to standardize assessment methodologies. The ultimate goal is to objectively and comparably manage the impact and evolution of environmental noise caused both by urban agglomerations and by traffic infrastructures (roads, rails and airports). The use of common indices and methodologies (together with five-year plan assessment required by the authorities in charge) should show how noise pollution levels are evolving plus the effectiveness of corrective measures implemented in the action plans. In this paper, available results from numerous European agglomerations (with particular emphasis on Spanish agglomerations) are compared and analysed. The impact and its evolution are based on the percentage of people exposed to noise. More specifically, it demonstrates the impact caused by road traffic, which proves to be the main noise source in all agglomerations. In many cases, the results are extremely remarkable. In some case, the results are illogical. For such cases, it can be concluded that either assessment methodologies have been significantly amended or the input variables to the calculation programs have been remarkably changed. The uncertainty associated with the results is such that, in our opinion, no conclusions can be drawn concerning the effectiveness of remedial measures designed within the action plans after the Directive’s first implementation Phase.
Open Access
Localization errors in binaural reproduction of first and third-order ambisonic recordings
(Convention of the European Acoustics Association, 2023-11-03) Pietrzak, A. P.; Sagasti, Amaia; Eguinoa Cabrito, Rubén; San Martín Murugarren, Ricardo; Ciencias; Zientziak; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza
It may be expected that high spatial resolution of a sound image obtained in higher order ambisonics should lead to smaller localization errors compared to first order. However, with binaural reproduction of ambisonic sound, the listener's ability to precisely localize the sound source may be reduced by the inaccuracies and spatial distortions made by the binaural decoders. This study compares the localization errors that occur when listening to pink noise bursts recorded with the use of first and third-order ambisonic microphones and presented binaurally through the earphones. It is discussed how in such a case localization errors vary depending on the ambisonics order and the type of the binaural renderer used. Localization errors were measured separately in azimuth and elevation. The median azimuth error was 25° for first-order and 20° for third-order recordings, with the front-back confusions excluded from the analysis. In elevation the median error for first-order was 65° and for third-order it was 100°, but it should be noted that in this plane front-back and up-down confusions were not omitted. Obtained results indicate no statistically significant differences between the four binaural decoders used.
Open Access
An efficient algorithm for the evaluation of tonality and the determination of the tonal frequency according to IEC 61400-11
(Institute of Noise Control Engineering, 2019) Arana Burgui, Miguel; San Martín Murugarren, Ricardo; Ezcurra Guisasola, María Amaya; Valencia Leoz, Ana; Llorente, Elena; Ciencias; Zientziak
The terms of tonality and tonal audibility of the noise emitted by wind turbines are defined and described in the standard IEC 61400-11. The procedure for tonality assessment at different wind speeds based on the narrowband analysis is explained in section 9.5 of the standard. After sorting spectra into wind speed bins, the overall tonal audibility is determined if at least six of ten of the narrowband spectra have an identified tone with the same origin. The standard describes a procedure for tonality assessment by means of a flowchart. Tones of the same origin are treated and reported as one tone. However, the standard does not specify the final value of the frequency of the tone. An efficient algorithm has been developed to evaluate the tonality of the noise emitted by wind turbines. Likewise, different alternatives to specify the final frequency of the tone are discussed, based either on their frequency of appearance in the total of the number of measurements or on the tone levels produced by such frequency.
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
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.