Ricardo San Martin

Using Noise Mapping to Evaluate the Percentage of People Affected by Noise

In noise mapping, the European Directive 2002/49/EC requires an estimation, to the nearest hundred, of the number of people living in dwellings that are exposed to different bands of Lden values in dB 4 m above the ground on the most exposed facade. Even though this methodology always overestimates the effects caused by noise, this estimation is accurate enough for detached or semidetached houses in urban areas. However, for large and tall buildings in urban configuration, this estimation could be confusing and even very vague. In fact, differences regarding the percentage of people affected by noise taken from an exact calculation and from European Directive criterion could be unacceptable. When facade noise map calculation is not possible, either due to being too time consuming or unavailability of software resources, estimating people affected by noise based on the nearest grid point approximation criterion is clearly preferable to the European Directive approach.

Uncertainties caused by source directivity in room-acoustic investigations

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.

People exposed to traffic noise in european agglomerations from noise maps. A critical review

Abstract 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 fromnumerous 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 signifi- cantly 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.

Impulse source versus dodecahedral loudspeaker for measuring parameters derived from the impulse response in room acoustics

This study investigates the performance of dodecahedral and impulse sources when measuring acoustic parameters in enclosures according to ISO 3382-1 [Acoustics-Measurement of room acoustic parameters. Part 1: Performance spaces (International Organization for Standardization, Geneva, Switzerland, 2009)]. In general, methods using speakers as a sound source are limited by their frequency response and directivity. On the other hand, getting impulse responses from impulse sources typically involves a lack of repeatability, and it is usually necessary to average several measurements for each position. Through experiments in different auditoriums that recreate typical situations in which the measurement standard is applied, it is found that using impulse sources leads to greater variation in the results, especially at low frequencies. However, this prevents subsequent dispersions due to variables that this technique does not require, such as the orientation of the emitting source. These dispersions may be relevant at high frequencies exceeding the established tolerance criteria for certain parameters. Finally, a new descriptor for dodecahedral sources reflecting the influence their lack of omnidirectionality produces on measuring acoustic parameters is proposed.

Influence of the source orientation on the measurement of acoustic parameters in a large reverberant cathedral

ISO 3382 standard describes both definitions and measurement procedures of different acoustic parameters derived from the room impulse response. Regarding to sound sources, most of the commercial dodecahedron loudspeakers comply with the maximum allowed directional deviations of the source specified in the standard. However, the influence of its specific orientation may affect the results obtained on some parameters more than their subjective just noticeable difference‐jnd‐ at least in rooms with no high reverberation times. An interesting aim is to study such influence in function of the liveliness of the room. A detailed measurement set is been carrying out in a reverberant place (Cathedral of Tudela, Spain) with the objective to analyze the influence of the sources orientation‐apart from its acoustic characterization. In addition to dodecahedron loudspeakers, pseudo‐impulsive sources are been used in order to compare results from a statistical point of view. Results obtained will be compared with thos...

Uncertainty versus parameter in room acoustics. A case study

An exhaustive characterization of the auditorium of Baranain (Navarre, Spain) has been carried out. All acoustic parameters (both monaural and binaural) in many seats (96 for monaural and 48 for binaural) have been measured for three source positions on the stage. For acoustic characterization, a countless results can be obtained in accordance (in all cases) with the views of the ISO-3382 for the presentation of the results. The spatial dispersion for each source position and combinations thereof will be shown. Accuracy on the acoustic evaluation of the room will be discussed from a statistical point of view.

Accuracy in the acoustical parameters evaluation according to ISO-3382

An exhaustive characterization of the new auditorium of the Navarre Conservatory of Music (Pamplona, Spain) has been carried out. All monaural acoustic parameters in all seats (375) have been measured for three source positions on the stage. For acoustic characterization, countless results can be obtained in accordance (in all cases) with the views of the ISO-3382 for the presentation of the results. The spatial dispersion for each source position and combinations thereof will be shown. Finally, the accuracy on the acoustic evaluation of the room will be discussed from a statistical point of view.

Calculating room acoustic parameters from pseudo‐impulsive acoustic sources

The impulse response function provides complete information to predict the acoustic response of a room to an acoustic input of arbitrary characteristics. At this job study, small explosions of firecrackers are proposed to be used as pseudo‐impulsive acoustics sources to determine some acoustic parameters of a room such as reverberation time, definition, and clarity, comparing these results to those obtained with other techniques. A previous characterization of these sources allows us to state that they can be used for this purpose because they are, in practice, omnidirectional, their temporary pattern is highly repetitive and their spectral power is, as well, repetitive and with enough power in octave bands from 125 Hz to 8 kHz. If the linear time‐invariant system impulse response h(t) is known, output signal s(t) regarding any arbitrary signal s(t) can be obtained. For our pseudo‐impulsive sources, the output signal s(t) has been taken as impulse response h(t). Using the integrated impulse response metho...

Acoustic insulation of recent flat buildings in Pamplona, Spain

The Municipal Government of Pamplona and the Housing Department of the Government of Navarra (Spain) decided to evaluate acoustic insulation of new flat buildings in Pamplona. Such study was ordered to the Acoustic Laboratory of the Public University of Navarra. During the last year, measurements relating to acoustic insulation were carried out in most of the new blocks of flats made in Pamplona. The results obtained show that acoustic insulation is insufficient in most buildings both for airborne sound reduction and for impact sound. The figures required by Spanish legislation do not fulfil in more than 80 percent of the cases. On the other hand, a great correlation between sound reduction figures obtained from index of ISO 140‐4 and from R (in dBA) of the Spanish norm for in situ measurements was carried out. A new Spanish legislation will be approved shortly.