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We carry out acoustic design activities for traditional office buildings, schools, hospitals and housing, as well as for large entertainment venues such as cinemas, theatres, auditoriums and opera houses.
We take care of all aspects of projects, studying the acoustic quality of the spaces, sound insulation between adjacent areas and protection from noise and the vibrations generated by mechanical systems.
We work on all the planning and design phases, from the preliminary studies to the final design, working drawings and specifications and the construction stage. We monitor the work carried out by conducting specialised observations in indoor and outdoor environments, with a view to guaranteeing compliance with the acoustic objectives established.
We provide support to professionals and businesses, because maximising the acoustic quality of a project and its implementation means improving people’s lives.
The acoustic behaviour of a closed space can be described using statistical theory, founded on the hypothesis of a perfectly uniform acoustic field throughout the environment on account of the absolutely random distribution of the propagation directions of the sound waves it is derived from. It will therefore be described by the mean values of the characteristic magnitudes. This method, based on the Sabine equation, can be used to effectively describe the reverberation phenomenon and to conduct a “quantitative” analysis of the materials that can effectively be used to control it.
The acoustic behaviour of a closed space can be described using the geometric method, which simplifies the situation by representing the sound waves using rays, derived from a source, which can propagate through the environment, reflecting off surfaces according to the laws of geometric optics. This is the system used in the acoustic simulation software used for “qualitative” project assessments, which evaluate the position and efficacy of the materials proposed, provided that the larger dimensions of the room studied is much larger than the wavelengths involved. This approach has no sense for smaller rooms with smaller volumes, for which the statistical method approach is sufficient.
To aid the design of acoustic insulation in buildings, the evaluation of passive acoustic requirements (Prime Ministerial Decree of 5/12/1997 and and UNI 12354 standards) and the acoustic classification of buildings according to the UNI 11367 standard, a software modelling tool should be used to take account of all possible structure-borne noise, in addition to the manual calculations of the construction packages.
When sound waves collide with a surface, they generate sound reflection, sound diffusion and sound absorption phenomena, depending on the physical properties of the materials the surface is made of. The acoustic quality of a confined environment will therefore depend directly on how these phenomena are managed and on the choices that must be accompanied by a detailed predictive study using all the methods and technologies available in order to optimise project choices.
Quando le onde sonore impattano contro una superficie, si generano fenomeni di fonoriflessione, fonodiffusione e fonoassorbimento del suono a seconda delle proprietà fisiche intrinseche dei materiali che la costituiscono. La qualità acustica di un ambiente confinato, dunque, dipenderà direttamente dalla gestione di tali fenomeni e dalle scelte che dovranno essere accompagnate da uno studio previsionale dettagliato che utilizzi tutti i metodi e le tecnologie a disposizione al fine di ottimizzare le scelte progettuali.
When a system of sound waves meets an object that is unable to vibrate, the waves reflect with a norm common to all such phenomena, according to which the angle of incidence is equal to the angle of reflection. The intensity and quality of the reflection depends on the characteristics of the reflecting surface. In any case, the part of the energy that is not reflected is absorbed or refracted. To study the contribution made by sound reflecting panels, in order to optimise positioning in section and in plan, a study is carried out of the first reflections and the “sound illumination fields” produced by the sound reflections according to the acoustic theory of ray optics. The calculation of the contribution made by sound reflecting panels to listening quality, and therefore of the different routes travelled by direct sound and reflected sound, and of the range of frequencies of interest the pertinent reflections should be applied to, enable the identification of the positioning in plan and in section and the angulations, as well as the depth, density and thickness of the individual panels.
To optimise sound insulation, the construction packages that make up the vertical and horizontal partitions of a building, as well as the door and window frames, must be designed adequately. For this purpose, there are two physical principles that can boost the sound insulation performance of walls and floors: the “law of mass action”, suitable to assess the performance of monolithic walls, and the principle known as “mass-spring-mass, to be applied to counter-walls or light walls. Choices must be made based on the limits set by the regulations in force and the performance objectives established.
An EVAC system is “an electroacoustic system mainly designed to transmit information to protect people in one or more specified areas during an emergency […]. It is used for the swift, orderly mobilisation of the occupants of an area inside or outside, in an emergency situation”: this is the definition provided in the current CEI EN 50849 Standard “Sound alarm systems of emergency applications”, in force since February 2019. This system is mentioned in the Fire Prevention Code, in paragraph G.1.14 “Active protection”, meaning the antifire measures suitable to reduce the consequences of a fire, requiring either human intervention or the activation of an antifire system.
We design audio video systems for conference rooms, meeting rooms, public entertainment venues, cinemas, theaters and auditoriums according to the latest generation standards and technologies.
Compliance with passive acoustic requirements requires works not only to be designed effectively, but also to be carried out properly. To verify that the requirements established at the design stage have been achieved and that the regulatory limits set out in the Prime Ministerial Decree of 5/12/97 have been complied with, the passive acoustic requirements must be tested on-site. This testing must be conducted by an environmental acoustics technician, using measurements performed in accordance with the procedures indicated in the UNI EN ISO 140 standards, using the appropriate instruments (class 1 sound level metre, dodecahedral source, unidirectional speakers and tapping machine). Once the measurements have been taken, the technician calculates the assessment scores in accordance with UNI EN ISO 717-1/2 and drafts the test report indicating whether the passive acoustic requirements have been complied with.
The first environmental acoustic parameter to be measured was reverberation time, by Sabine, at the end of the 19th century, and this remains the most important descriptor in analysis and in the acoustic design of a confined space. Reverberation time is defined as the time interval between the moment the source of the acoustic signal has been turned off and the moment the energy density is reduced to one millionth of its original intensity. Reverberation time is measured by estimating the decay of the sound produced by the sound excitation, which may occur in three ways: interrupted noise, impulsive source and ‘Sweep-Sine’ exponential sinusoidal sweep. Interrupted noise consists of excitation of the environment using an omnidirectional source driven by a power amplifier that generates a broad-spectrum (from 50 Hz to 10 kHz) white noise, and when the source is interrupted, using a sound level meter, the decay time is measured. The advantage of the impulsive signal is that it can be generated easily by an explosion, which can be obtained, for example, by firing a gun; the impulsive signal is short and thus allows excitation to be distributed simultaneously across a broad frequency band.
The Speech Transmission Index (STI) is an indicator of mean speech intelligibility. STI scores range from 0 (completely unintelligible) to 1 (excellent intelligibility). The STI has been correlated to subjective intelligibility scales. The methods for measuring intelligibility are based on the determination of the modulation transfer function (MTF) in 7 octave bands, and must be carried out using specific instruments. STI measurement is one of the methods applied to test, for example, signalling and alarm systems.
Surveys conducted in living environments measure levels of both environmental and residual noise. Environmental noise level is the A-weighted equivalent continuous noise level, produced by all the sources of noise present in the environment under investigation; therefore, it is made up of residual noise plus the noise produced by the specific disturbing noise sources, with the exclusion of individually identifiable sound events of an exceptional nature, and is the level that is compared with the maximum exposure limits. Residual noise level is detected when the specific disturbing noise source is excluded from the measurement. It must be measured with methods identical to those used for measuring environmental noise.
Prime Ministerial Decree no. 215/99 established the maximum noise levels permissible in entertainment and public performance venues and in public establishments (excluding temporary and mobile activities) equipped with electrical sound transmission and amplification systems. The regulation establishes the maximum sound pressure limits to be complied with in order to limit exposure to noise. It is necessary to verify whether the system is equipped with features able to potentially exceed the limits.
If the system is able to exceed the limits, an acoustics technician will indicate the actions necessary to bring the system back within the limits established in the regulations. Once these actions have been implemented, the technician must test the system and issue a technical report to be attached to the Self Declaration made by the manager of the activity.
We support the design process with regard to all environmental aspects. The evaluations we conduct apply both to the project stage and the subsequent operational stage, and may be supplemented by experimental measures and simulation calculations using dedicated software. Together with the environmental prefeasibility/feasibility studies and environmental impact studies, we also set out the subsequent environmental monitoring plans to control each and every stage of a project.
With regard to predictive simulations, we analyse noise, vibrations, air and electromagnetic fields, using instruments such as SoundPLAN, Caline, Calpuff, WinDimula and Magic. From an experimental point of view, we measure noise levels and vibrations in accordance with current regulations.
We provide support to public entities and businesses with the aim of preserving and improving the environment we live in.
Acoustic studies are carried out using the SoundPLAN simulation software to create horizontal and vertical noise maps and to map noise at façade level at the receptors and to make calculations on sensitive receptors. It is also possible to establish and design a series of noise mitigation measures to resolve any critical issues detected with regard to the regulatory limits established.
Predictive analyses are carried out using the proper instruments, selected based on the sources to be assessed: for linear noise sources, such as roads, the Caline software is used, while for aerial or particular noise sources, we use Calpuff (with a Langrangian model approach) or WinDimula (with a Gaussian model approach). The model produces colour maps of the isoconcentrations for the main pollutants and precise table values of those pollutants as calculated on discrete receptors.
MAGIC (MAGnetic Induction Calculation) software can be used to calculate the colour map of the magnetic induction generated by a series of conductors in which an arbitrary current is applied.
Each phase of a project requires a detailed examination of the related environmental issues. The purpose of environmental pre-feasibility studies (for the preliminary project phase or the technical and economic feasibility project) and feasibility studies (for the final design phase) is to establish the expected impacts, starting out from the existing situation, and to design the pertinent mitigation and compensation systems. The environmental impact studies, necessary for some types of works, provide the key to determining the intervention required and the solution for integrating it into the environmental and territorial fabric it will be interacting with. A multi-disciplinary approach is used to directly and exhaustively determine the pressures regarding noise/vibrations/the air, taking account of the surrounding landscape and nature detailed in the Landscape Report and the Environmental Implications Assessment. Assessments are also conducted regarding the vulnerability and climate risk of the works.
Diapason Ingegneria supports the decision-making framework of Strategic Environmental Assessments, introducing considerations of an environmental nature into plans and development programmes to improve the overall quality of the planning process.
These involve establishing how environmental quality surveys are to be carried out, and the environmental matrices to be examined, as well as the monitoring stations for the aspects examined in the environmental studies and for which it has been possible to estimate an impact and subsequently define mitigation/compensation measures. The aim of the measures is to assess the initial conditions, the modifications expected while the works are being carried out and the situation after they have been completed, verifying the efficacy of the mitigation/compensation actions proposed and the actions for the recovery and restoration of the places compared to the initial conditions. The estimated bill of quantities for the proposed Noise Mitigation Plan is also determined.
Analytical methodologies are studied and designed to assess the environmental footprint of a product or service, taking account of the environmental impacts generated throughout its life cycle (from the raw materials through to production, distribution, use and ultimately disposal).
The AIA applies to the activities in the second part of Annex VIII of Italian Legislative Decree no. 152/2006 as amended, and requires the use of the Best Available Techniques (BAT) to reduce air, water and soil pollution, and waste production, as far as possible. Diapason Ingegneria provides support for the drafting of all the necessary documentation for the submission of the procedure to the regional authorities, or, for particular limits, to the Ministry of the Environment and Energy Security. The industrial categories it applies to include energy, production and processing of metals, mining products, the chemical industry, waste management and other manufacturing activities. The environmental authorisations that form part of the AIA regard emissions, authorisations for the discharge, disposal and recovery of waste, and other aspects of an environmental nature.
Plants not subject to the AIA measures, and specifically the categories of businesses mentioned in article 2 of the Ministerial Decree of 18 April 2005, must initiate a Single Environmental Authorisation procedure. For this procedure, to be submitted to the SUAP (the single business advisory centre), environmental documentation must be drafted regarding discharges, effluents, sound and air emissions, the use of sludge in purification processes and communications regarding waste.
Mobile device used to conduct campaigns for acquiring the main pollutants, to be defined in terms of duration and type of sampling based on the sources and the potential receptors.
We have all the instruments necessary to carry out timely or prolonged monitoring of environmental aspects.
We carry out measurements in indoor areas regarding the acoustic comfort of adjoining spaces, in accordance with the specific uses of the spaces and with safety in the workplace, in observance of Legislative Decree no. 81 of 2008, and in indoor areas regarding the spread of polluting substances in the air.
We operate on civil and infrastructure construction sites, for the purpose of monitoring the pertinent environmental aspects and whether they are in line with the predictive studies conducted, detecting any variations during the construction process so that the necessary corrections can be made in order to achieve the objectives established.
In internal and external environments, technological systems transmit noise through the air and vibrations through structures. To eliminate these undesired effects, a number of mitigation strategies can be adopted, based on separating the machinery from the base it rests on (to prevent the transmission of vibrations) and the application of appropriate silencers to the exhaust fan, soundproof splitters on the filter sections of the machinery, and actual noise barriers to be placed between the source and the receptors that may be disturbed (to prevent the transmission of noise through the air).
The design of a noise barrier is composed of two stages: first, a predictive study is conducted for the acoustic characterisation of the post-operam scenario, and therefore the efficacy of the work. This is followed by the executive project, which describes the work in full, with all its construction components.
A municipal acoustic classification (acoustic zoning) plan is a technical and political action that consists of dividing municipalities into acoustically uniform areas, following a careful urban planning analysis of the territory that involves studying the technical report of the Local Strategic Plan (PRG) and the pertinent implementation regulations. The aim of the classification is to prevent the deterioration of zones not affected by noise pollution, and to provide an indispensable planning tool for the development of urban planning, business, craftsmanship and industry.
For new constructions, a study must be carried out to predict noise impact. This study must certify that the new construction/infrastructure will be located in an acoustic setting consistent with the acoustic classification for the pertinent area (acoustic zoning). For this reason, an adequate noise level measurement campaign must be carried out in the area concerned, in order to determine the emission and immission levels in the two reference periods (day and night) and to verify compliance with the statutory limits in force. At the study stage, it is also necessary to consider the impact the new construction may have in terms of noise due to its technological systems or to substantial changes to the surface traffic system. If the limits are likely to be exceeded, noise control measures must be envisaged.
Class 1 sound level metres are used to carry out spot noise level measurements, with or without specific sampling techniques (for example MAOG for road-type sources), and short or long continuous noise level measurements (24h or weekly/biweekly). The company is equipped with adequate instruments for external stationing and for the acquisition of meteorological data. For road sources, noise level measurements can be completed with continuous measurements of road traffic, with automatic sampling stations and flow acquisition systems. For the purpose of acoustic studies, contextual or targeted campaigns are also conducted for the identification of receptors that may be affected by a project or an activity, with planimetric classifications and data sheets of the structures identified.
Spot vibration measurements conducted in buildings to assess disturbance according to the UNI 9614:2017 technical regulation, using a triaxial accelerometer.
Class 1 sound level metres are used to carry out spot noise level measurements, with or without specific sampling techniques (for example MAOG for road-type sources), and short or long continuous noise level measurements (24h or weekly/biweekly). The company is equipped with adequate instruments for external stationing and for the acquisition of meteorological data. For road sources, noise level measurements can be completed with continuous measurements of road traffic, with automatic sampling stations and flow acquisition systems. For the purpose of acoustic studies, contextual or targeted campaigns are also conducted for the identification of receptors that may be affected by a project or an activity, with planimetric classifications and data sheets of the structures identified.
Spot vibration measurements conducted in buildings to assess disturbance according to the UNI 9614:2017 technical regulation, using a triaxial accelerometer.
Surveys conducted in living environments measure levels of both environmental and residual noise. Environmental noise level is the A-weighted equivalent continuous noise level, produced by all the sources of noise present in the environment under investigation; therefore, it is made up of residual noise plus the noise produced by the specific disturbing noise sources, with the exclusion of individually identifiable sound events of an exceptional nature, and is the level that is compared with the maximum exposure limits. Residual noise level is detected when the specific disturbing noise source is excluded from the measurement. It must be measured with methods identical to those used for measuring environmental noise.
Noise risk assessments and assessments of the level of exposure to noise in the workplace were made mandatory by Italian Legislative Decree no. 81/08. Measurements for the assessment of exposure to noise are carried out using group 1 IEC 651 or IEC 804 (CEI EN 60651 and CEI EN 60804) instruments. The duration of the surveys depends on the variability of the noise over time, and lasts in any case until the instrument has substantially stabilised; the measurements are carried out by placing the sound level meter at a distance of 15 centimetres from the ear of the operator in their usual position at work, although they are also followed in their activities in the vicinity of the machinery and the workstations.
Annex C of the Decree of 16 March 1998 established how railway noise is to be measured. Measurements must be conducted in normal railway traffic conditions, and without rain, fog and/or snow; wind speed must be no higher than 5 m/s. The microphone must be covered with a windsock, and it must be facing the noise source and positioned at a distance of 1 m from the façade of the receptors analysed and at a height of 4 m from the ground. The acquisition of sound pressure levels must be set with a fast time constant, and must be able to determine the start time, the sound exposure level LAE and the temporal profile LAF(t) of the individual passages of the convoys. Measurement time TM must be no less than 24h. The Ministerial Decree of 31 October 1997 defined the methodology for measuring airport noise. Airport noise can be measured using an assisted system, for measurements carried out using mobile instruments able to measure at least the sound exposure level of aeronautical aircraft movements, and a non-assisted system, specifically for fixed monitoring measurements, which is able to automatically identify overflight profiles and to attribute the corresponding SEL value to each one of them.
Italian Law no. 447/95 “Framework law on noise pollution” was formulated to protect outdoor and living environments from noise pollution. A sound source should not cause noise in the outdoor or living environment that is loud enough to be unpleasant or disturb rest and human activity, pose a danger to human health, or is intense enough to interfere with the legitimate right to use said environments. For this reason, the public administration requires (Prime Ministerial Decree of 14/11/1997) that before a new business begins operating, a NOISE IMPACT ASSESSMENT (DPCM 14/11/97) must be conducted by an Environmental Acoustics Technician regularly enrolled on the dedicated National Register, in order to verify whether the systems pertaining to the new business are compliant with the limits established by the regulations in force regarding acoustics, and that they will not, therefore, disturb third parties.
Permanent or temporary public entertainment activities must undergo a noise impact assessment. Issue of permits is therefore conditional upon an assessment conducted by an Environmental Acoustics Technician regularly enrolled on the pertinent National Register, who must ascertain compliance with the limits set by the regulations in force regarding acoustics.
With regard to temporary public entertainment activities, if the Technician entrusted with conducting the assessment considers that the regulatory limits are likely to be exceeded, authorisation may nonetheless be requested in exemption of the acoustic limits. The noise impact study and the exemption request must be submitted to the public administration, which will send the documentation to the Regional Environmental Protection Agency (ARPA) for their opinion before issuing the permit.
Temporary construction site activities must undergo a noise impact assessment. Issue of permits is therefore conditional upon an assessment conducted by an Environmental Acoustics Technician regularly enrolled on the pertinent National Register, who must ascertain that the noisy activities envisaged on the construction schedule are compliant with the limits set by the regulations in force regarding acoustics.
If the Technician entrusted with conducting the assessment considers that the regulatory limits are likely to be exceeded, an exemption may be requested that takes account only of the immission limit at the receptor at which the greatest disturbance is likely to be caused. The noise impact study and the exemption request must be submitted to the public administration, which will send the documentation to the Regional Environmental Protection Agency (ARPA) for their opinion before issuing the permit.
Italian Law no. 447/95 “Framework law on noise pollution” was formulated to protect outdoor and living environments from noise pollution. A sound source should not cause noise in the outdoor or living environment that is loud enough to be unpleasant or disturb rest and human activity, pose a danger to human health, or be intense enough to interfere with the legitimate right to use said environments.
Although it is mandatory for businesses to have a noise assessment conducted, immissions may nonetheless occur in living environments close by that exceed the differential limit (5 dBA during the day and 3 dBA at night). Cases such as this may be reported to the municipal council, which will instruct the Regional Environmental Protection Agency (ARPA) to carry out all the noise level measurements necessary to verify compliance with the regulatory limits. If these have been exceeded, the business must appoint an Environmental Acoustics Technician regularly enrolled on the dedicated National Register to draft an acoustic remediation plan to bring noise emissions/immissions back within the statutory limits. The report to the council may be accompanied by an expert report by a qualified technician. This is the administrative procedure governing the relations between businesses and private citizens (public law criterion).
Relations between private citizens are governed by art. 844, which defines “normal tolerability”, i.e. the maximum limit of immissions (including noise immissions) possible within the property of others.
The normal tolerability limit established by case law has been identified as 3 dB between the immission level and the background noise level (i.e. the level measured without the source causing the disturbance). In the case of relations between private citizens, the first step for the case to be taken to court is of course a survey carried out by an Environmental Acoustics Technician regularly enrolled on the dedicated National Register, and a report certifying that the legally established limits have been exceeded.
The legal criterion that requires the verification of compliance with the normal tolerability limit is also applicable to relations between private citizens and businesses; however, this criterion is not subject to verification in the noise impact report drafted by the qualified technician.
We carry out educational and teaching activities on architectural and environmental acoustics for public and private entities, providing training courses and professional further training courses for Environmental Acoustics Technicians.
