Interview | Mario Mattia

We spoke to Prof. Mario Mattia, who has been an acoustics specialist since 1972 and has a MA and has attended specialisation courses at Brüel & Kjær A/S in Denmark. Lecturer in Acoustics at the University of Tor Vergata (Rome) and Roma Tre (Rome). Founder and President of EuroAcustici, an association which, since 2001, has aimed to improve scientific knowledge on technical, environmental, ergonomic and cybernetic problems related to the quality of life, with a particular focus on acoustic problems induced by noise and vibrations in the sphere of communication, work and society.

The conversation began with a reflection on the common neurosensory terrain of olfactory and acoustic perceptions: smells and sounds are both linked to survival and both processed in the limbic area.

Mario Mattia: The limbic area has a key function in emotional reactions and in the process of memory and smell. Everything we perceive is stored in our memories and this record can be permanent. In other words, if we perceive a noise that alarms us, and with which we associate danger, this fear stays with us so that whenever we are in a stressful situation we can experience auditory and physical problems associated with that fear. Many idiopathic disorders have the same origin: stress and the stored fear associated with it can generate tinnitus, phobias and eating disorders, such as bulimia and anorexia.

Acoustics are totally underestimated both at the level of workers and the general public’s perception, and also at the legal level.

Elena Giulia Abbiatici: In this respect, how have the regulations been updated over time and how has the attitude of institutions changed with regard to this issue?

Mario Mattia: There are private rules (Civil Code Article 844) and administrative rules (Framework Law on Noise Pollution 447/95) that have completely different implications.

The former concerns the exceeding of the measure of normal tolerability for the protection of property. Article 844 of the Civil Code states: “The owner of a property cannot prevent the input of (…) noise, movement and similar transmissions originating from neighbouring property, on condition that they do not exceed normal tolerability, while also taking into account the actual condition of the premises.”

From a metrological point of view, the starting point for noise is the background level (statistical minimum LAF95%) – a level that is not absolute but relative to the environmental situation. This level cannot be increased by more than twice its energy: for noise and vibrations, this increase corresponds to a maximum increase of three decibels, an apparently low value that, in any case, depends on the subjectivity of the individual. Let us clarify the meaning of the three decibels: if the noise level of a machine is 60 decibels, I turn on a second machine nearby that emits the same 60 decibels, but the sum of the two machine levels is not 120 decibels but only 63 dB. If I hear my neighbour’s piano in the house, the screams of the newborn baby next door, the dog barking, the sound of bells, disco music, the neighbour’s air conditioner, footsteps at night from the floor above… if these perceptions are insistent and repeated, they can create a situation of stress and alarm. Very often, a situation that is “not tolerable” for an individual, i.e. excessively disturbing, is considered “acceptable” under administrative law. The administrative rules are based on Law 447/1995, the framework law on noise pollution, which does not protect health, but is used by a local council to issue a noise impact clearance authorisation when a permit is required to open an activity. The permit is only issued by acoustically competent technicians (qualified by LEGISLATIVE DECREE no. 42 of 17 February 2017) as an administrative certificate.

It is an offence for a person to exercise a profession without being registered as part of a professional registry or directory.

The administrative assessment for the public administration is not linked to the private assessment of the tolerability of the disturbance. There are different aspects which may create a legal conflict: the private standard is based on the Civil and Criminal Code, while the administrative standard is based on the framework law that legitimises the acceptability of noisy activities.

In fact, as I was reading Framework Law 447, I noticed that it only relates to the administrative management that the State, Regions and Local Councils take on when regulating authorisations and limiting noise pollution in cities. In short, keep as far away as possible from individual issues…

Yes, the framework law is limited, intended to create minimum control over the environment and not to protect citizens’ rights or their psycho-physical health. It has to be said that many administrative regulations, such as the passive acoustic effects of buildings, are often disregarded: noisy activities and builders do not respect legal limits. Builders would have to carry out an assessment every time to evaluate the passive acoustic performance of each flat (soundproofing between residential units, insulation from the noise of footsteps, noise from installations and neighbourhood drains, etc. – technical assessments required by law and costing over €1,000 per flat); in fact, builders would rather send the PPAA (local authority) computer-aided assessments (where everything is in accordance with the law so the local authority accepts it) thus risking not meeting the minimum legal requirements. The builder or seller simply hopes that the citizen who buys a flat will not sue. In practice, when the new flat owner hears the voices of neighbours and footsteps from upstairs, they order a technical report to be carried out by an acoustics expert and find that the legal limits have not been respected. They can then sue and the civil court, finding a lack of soundproofing, penalises the person who sold the flat by refunding 20-30% of the purchase price. The measurement methodology is precisely and unambiguously stipulated by the D.P.C.M. 5/12/97 “Determination of buildings’ passive acoustic requirements”, which sets numerical values for sound insulation of wall structures and noise levels of apartment blocks or neighbouring buildings. Expert opinions and lawsuits mainly occur in Northern and Central Italy, but they are spreading all over the country due to the certainty of the outcome.

This is a real and frequent problem in cities where many old houses are being renovated… Apart from noise insulation in flats, how do private and administrative regulations deal with noise generated by construction sites?

The owner of the building site must apply to the local council for a temporary special permit so that the limits are suspended. The authorisation procedure must be issued stating hours of work, duration of the work and noise barriers to reduce neighbourhood disturbance.

How can citizens deal with excessive sources of noise? How can they protect their rights and their health?

You have to find a serious acoustic consultant who can document, using phonometric analyses, whether the noise exceeds “normal tolerance” levels. If the consultant confirms the pollution situation with an objective report, there is no need to call the police or ASL, etc. The only public body responsible for local noise pollution is ARPA, which must be activated through a complaint to the “acoustic impact” office of the local council (or by the mayor). This is necessary to avoid any confusion between the comparative criterion of the assessment of “normal tolerability”, which is derived from case law, and the differential criterion of “acceptability”, which is derived from administrative or public anti-pollution provisions.

What new architectural designs can be used in our cities to contain noise, and also in our schools? What are the best sound insulators in buildings and urban locations?

Enclosed spaces are protected from internal noise by sound-absorbing materials, whereas buildings are shielded from external noise by sound-insulating materials.

In all these years of work, have you seen regulations updated or changed?

The passive acoustic requirements standard includes an update introducing a similar criterion to that used for thermal insulation. Window insulation and other insulation between flats are passive acoustic requirements. A draft standard exists, but it has never been approved. I am now in contact with the Ministry of the Environment, which is in charge of the matter, but as far as construction is concerned, everything is at a standstill. Nowadays, unfortunately, building work is often not done very well and you can hear your neighbour talking, even if he is speaking normally, because there is no soundproofing…

What about other European countries?

They are much stricter.

Where can a virtuous model be found?

In central and northern European countries. The further north you go, the more careful they are.

There is indeed a different cultural attitude. People talk quietly, the noisy Mediterranean approach is quite evident… How is the issue also dealt with from a medical and forensic point of view?

We have occupational doctors who do a series of checks on potential acoustic hazards in the working environment; then we have ENT specialists who study the response of the auditory system, to assess any hearing loss in either low or high frequencies.

When acoustic stress is high, hair cells can break down and there is permanent cochlear damage. We are talking about long term (years) exposure to high noise levels leading to permanent deafness (PTS); for short term exposure we can have a temporary lowering of the hearing threshold where hearing loss can be quickly recuperated (TTS). If the hair cells break, they can no longer be rebuilt causing sensorineural damage.

Can you name some types of hearing disorders?

Noise-induced deafness (PTS), hearing fatigue (TTS), sudden sensorineural hearing loss and tinnitus. Noise also interferes with the endocrine system, the central nervous system, the psyche and behaviour, the cardiovascular system, the gastrointestinal system and the respiratory system. It can cause neurovegetative dystonias and stress, and also worsen physiological dysfunctions already present in a latent or evident form. Acoustics is the science of elastic vibrations and sounds are waves travelling through the air.

(ed. See the figures published in the following report: https://www.inquinamentoacustico.it/dowload/Linee_guida_rumore_ambientale-who_europa_2018.pdf

In fact, noise has always been used by libertarian regimes as an instrument of torture, to generate stress and negatively affect various parts of the body. Is tinnitus very frequent or does it seem to be a rather incidental problem? Are there any valid remedies?

TRT (Tinnitus Retraining Therapy), if conducted by specialised rehabilitation staff, is one of the crucial elements in tinnitus treatment programmes, on which the success of the entire treatment programme may depend. A protocol exists that is only applied in cases where the disorder is idiopathic (not clinically diagnosable). It acts on the memory mechanism so that the recording in our memory of the fear of whistling (tinnitus) is disconnected from the sensation of danger. This consists of meditation practices and listening to non-masking low-level sounds. Tinnitus Retraining Therapy has been developed over the last ten years. It is autogenous and does not involve the use drugs, meaning that doctors are not interested in recommending it.

Can you tell us about the relationship between hearing and the cardiovascular, gastrointestinal, respiratory, endocrine and central nervous systems?

A state of stress affects the limbic area and a number of physiological phenomena ensue, which do not have a clinical basis. In other words, tests do not reveal anything, but the acoustic stress unbalances the whole body. It always goes back to the memory game. Living beings are electromagnetic machines. Everything we perceive generates an electrical impulse that reaches the limbic area, where it is analysed, filtered, decoded and then transmitted to the cerebral cortex for mnemonic perception. Everything we see is not always real, but it is what is generated by memory control. If a person loses an arm in an accident, their memory will continue to make the presence of the arm felt.

Ah, of course, the acoustic phantoms… I read in Oliver Sacks’ book Musicophilia that completely hearing-impaired people can experience auditory hallucinations to compensate for total silence.

Even the absence of noise is scary because we have to perceive our surroundings to feel secure. Man records everything that happens in life and we do not have the ability to consciously relive certain events except through hypnosis, or through other techniques that make subjects reexperience deep stress. Many years later, in stressful and dangerous situations, forgotten stressful experiences can re-emerge. There are idiopathic disorders, e.g. tinnitus, which have no clinical cause and, according to doctors, no remedies. This is not true, because the human brain is plastic and has an incredible capacity to regenerate itself. It was once said that neurons do not renew themselves, but this theory has been disproved. There are even people who have had half of their brain removed and after a certain amount of time they can talk, run, etc. again. The remaining hemisphere acquires the information of the removed hemisphere. The auditory system also functions in a coma, i.e. there is brain activity even during a coma.

Are there alternative devices to cochlear implants? Again, in Musicophilia, I read that acoustic perception not only becomes mechanical but is also extremely reduced in terms of nuance, pitch, voice and sound colours.

Of course, this is an extreme technique in cases where the subject still has a functioning auditory nerve. There are approximately 20,000 hair cells, while the electrical cord of the cochlear implant has approximately 8-10 pulses, so the perception of sound is unnatural. It is an extreme technique that otologists apply, but it can create serious problems for patients because it is very invasive.

Two points are recorded in audiometry: low-medium frequencies and high frequencies. Where the former is damaged, often due to otosclerosis (welding of the “stirrup”, the middle ear’s ossicle, to the mastoid bone), microsurgery is used to replace the stirrup with an artificial bar. Where there is high frequency damage, this cannot be remedied. Research is ongoing, but at the moment there is no effective or decisive technique available; there is a sound amplifier, which compensates for the loss. The maximum amplification must also be set gradually to allow our brain to progressively adapt. Let us not forget that presbyacusis, the decline in hearing with age, is also caused by drugs – antibiotics, anti-inflammatory drugs, antimalarials, antifungals – most of which are ototoxic. (https://euroacustici.org/FARMACI_OTOTOSSICI_MM.pdf).

There are people living in forests who do not experience deafness because they use only natural medicines, are not in contact with urban noise and eat unpolluted food. Nutrition is crucial because it modifies the immune system and probiotics in the gut, which are responsible for the proper functioning of the whole body.

In the near future, will brain implant devices be developed to transmit acoustic information directly to the cerebral cortex?

Biocybernetic research is working on how to transmit bio-electrical information to the brain without passing through the auditory organs. At the moment this is still a distant goal and would apply to all the senses; smell and hearing are certainly the senses most related to survival, functioning even in a coma, so they are potentially the first in which such research could be successful.