Low frequency noise and disturbance assessment methods: A brief literature overview and a new proposal
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paper_title: Study and Assessment of Low Frequency Noise in Occupational Settings

paper_content:

Low frequency noise is one of the most harmful factors occurring in human working and living environment. Low frequency noise components from 20 to 250 Hz are often the cause of employee complaints. Noise from power stations is an actual problem for large cities, including Cairo. The noise from equipments of station could be a serious problem for station and for environmental area. The development of power stations in Cairo leads to appearing a wide range of gas turbines which are strong source of noise. Two measurement techniques using C-weighted along side the A-weighted scale are explored. C-weighting is far more sensitive to detect low frequency sound. Spectrum analysis in the low frequency range is done in order to identify a significant tonal component. Field studies were supported by a questionnaire to determine whether sociological or other factors might influence the results by using annoyance rating mean value. Subjects included in the study were 153 (mean = 36.86, SD = 8.49) male employees at the three electrical power stations. The (C-A) level difference is an appropriate metric for indicating a potential low frequency noise problem. A-weighting characteristics seem to be able to predict quite accurately annoyance experienced from LFN at workplaces. The aim of the present study is to find simple and reliable method for assessing low frequency noise in occupational environment to prevent its effects on work performance for the workers. The proposed method has to be compared with European methods.
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paper_title: Options for Assessment and Regulation of Low Frequency Noise

paper_content:

Dutch legal limits for Lden noise levels are different for road traffic, railways, industry and airports. A justification for these differences might be found in the difference between dose-response relationships for noise annoyance. Nevertheless, frequently situations occur where people severely complain of low frequency noise, even when Lden levels amply comply with limits. So far, an effective regulation specifically for low frequency noise is not available. This paper discusses some options for improving the protection for LFN annoyance from Lden legislation. A potential solution might be to penalize Lden levels based on low versus high frequency ratio and tonality. This paper describes how such an approach is applied for a number of LFN cases in the Netherlands and discusses the results.
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paper_title: The Central Role of Interpersonal Conflict in Low Frequency Noise Annoyance

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This paper considers the relationship between the Environmental Health Officer and the Low Frequency Noise complainant (sufferer). It is suggested that the characteristic psychoacoustic properties of Low Frequency Noise may interact with inappropriate assessment protocols to produce a series of interpersonal pressures that play an active part in shaping the overall noise problem. This interaction may be considered as a legitimate and common impact factor within Low Frequency Noise complaints. The confounding role of misperception and miscommunication, between the parties, is explored and models of conflict resolution are considered as a means for providing counter measures to the behavioural consequences of failed assessment procedures and ineffective personal coping strategies.
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paper_title: Danish Guidelines on Environmental Low Frequency Noise, Infrasound and Vibration

paper_content:

In Denmark a set of guidelines for measurement and assessment of environmental low frequency noise, infrasound and vibration was published in 1997 as “Information from the Danish Environmental Protection Agency no. 9/1997” (Miljøstyrelsen2). Recommended measurement methods are specified, and recommended limit values for noise and vibration are given. In this paper a brief description of the measurement methods is given, the recommended limit values are shown, and the background for the measurement and assessment methods is discussed. This paper is an extended summary of “Information from the Danish Environmental Protection Agency No.9/1997” (in Danish)
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paper_title: Annoyance from transportation noise: relationships with exposure metrics DNL and DENL and their confidence intervals.

paper_content:

We present a model of the distribution of noise annoyance with the mean varying as a function of the noise exposure. Day-night level (DNL) and day-evening-night level (DENL) were used as noise descriptors. Because the entire annoyace distribution has been modeled, any annoyance measure that summarizes this distribution can be calculated from the model. We fitted the model to data from noise annoyance studies for aircraft, road traffic, and railways separately. Polynomial approximations of relationships implied by the model for the combinations of the following exposure and annoyance measures are presented: DNL or DENL, and percentage "highly annoyed" (cutoff at 72 on a scale of 0-100), percentage "annoyed" (cutoff at 50 on a scale of 0-100), or percentage (at least) "a little annoyed" (cutoff at 28 on a scale of 0-100). These approximations are very good, and they are easier to use for practical calculations than the model itself, because the model involves a normal distribution. Our results are based on the same data set that was used earlier to establish relationships between DNL and percentage highly annoyed. In this paper we provide better estimates of the confidence intervals due to the improved model of the relationship between annoyance and noise exposure. Moreover, relationships using descriptors other than DNL and percentage highly annoyed, which are presented here, have not been established earlier on the basis of a large dataset.
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paper_title: Assessment criterion for indoor noise disturbance in the presence of low frequency sources

paper_content:

Abstract Several studies have presented the effects of environmental noise in and around buildings and communities in which people live and work. In particular, the noise introduced into a building is mostly evaluated using the A weighted sound pressure level ( L Aeq ) as the only parameter to determine the perceived disturbance. Nevertheless, if noise is produced by activities or sources characterised by a low frequency contribution, the measurement of L Aeq underestimates the real disturbance, in particular during sleeping time. The international literature suggests methods to evaluate the low-frequency noise contribution to annoyance separately from the A weighted sound pressure level; almost all of the proposed methods are based on exceeding a threshold limit. This paper tests international criteria, by applying them in real-life indoor noise situations, and then analysing, comparing and contrasting results. Based on the result of the procedure above, a new criterion consisting of a single threshold is proposed, which simplifies the procedures in case of low-frequency components, but could be used for any situation.
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paper_title: Sound power level of speaking people

paper_content:

In restaurants and cafes many sound sources are present: music, refrigerant and cooling equipment and people speaking. The smoking prohibition law (in force in Italy since 2005 for instance) did move out people, creating a lot of aggregation areas outdoor, both in summer and in winter time. As a matter of facts many cafes open on the outer part a stallage in order to provide beverages to outside costumers. In this way, the "people speaking" source became a common problem for the neighborhood to deal with and solve. In order to characterize this particular sound source in terms of sound power level of a typical stallage situation full of speaking people, sound pressure power measurements according to ISO 3746 standard [1] were carried out. The results confirm the first investigation achievements provided by Sepulcri et all [2] with a non-direct method.
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paper_title: Low Frequency Hearing Thresholds in Pressure Field and in Free Field

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Thresholds of hearing were determined in pressure field at frequencies fromp 4 Hz to 125 Hz. At the frequencies 4-25 Hz hearing thresholds were found that are in the lower middle of the range already reported by other investigators. At frequencies from 25 Hz to 1 kHz thresholds have already been determined in free field by the same method and using the same subjects. The two investigations overlap at frequencies from 25 Hz to 125 Hz, and in this range the results were almost identical. The differences were below 1 dB, except at 63 Hz where the difference was 2.5 dB. None of the differences was significant in a t-test
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paper_title: Assessment criterion for indoor noise disturbance in the presence of low frequency sources

paper_content:

Abstract Several studies have presented the effects of environmental noise in and around buildings and communities in which people live and work. In particular, the noise introduced into a building is mostly evaluated using the A weighted sound pressure level ( L Aeq ) as the only parameter to determine the perceived disturbance. Nevertheless, if noise is produced by activities or sources characterised by a low frequency contribution, the measurement of L Aeq underestimates the real disturbance, in particular during sleeping time. The international literature suggests methods to evaluate the low-frequency noise contribution to annoyance separately from the A weighted sound pressure level; almost all of the proposed methods are based on exceeding a threshold limit. This paper tests international criteria, by applying them in real-life indoor noise situations, and then analysing, comparing and contrasting results. Based on the result of the procedure above, a new criterion consisting of a single threshold is proposed, which simplifies the procedures in case of low-frequency components, but could be used for any situation.
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paper_title: Cortical Plasticity: Learning from Cortical Reorganisation

paper_content:

Neocortical circuits can undergo dynamic rearrangements, not only in response to injury, but also when new skills are acquired. But although training can lead to functional rewiring of the cortex, we are far from being able to reprogram an animal by manipulating its cortical circuitry directly.
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paper_title: Cortical Plasticity: Learning from Cortical Reorganisation

paper_content:

Neocortical circuits can undergo dynamic rearrangements, not only in response to injury, but also when new skills are acquired. But although training can lead to functional rewiring of the cortex, we are far from being able to reprogram an animal by manipulating its cortical circuitry directly.
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paper_title: Experimental Characterisation of the Low Frequency Noise Annoyance Arising from Industrial Plants

paper_content:

Complaints about low frequency noise annoyance are frequently reported although the sound levels, measured according to usual procedures, do not seem to justify such reactions. In the present paper some experimental data, gathered by the authors, are illustrated. The results are analyzed on the basis of the available methodologies with the aim of giving a useful contribution to the discussion about the necessity of a special methodology for the correct evaluation of the low frequency noise annoyance.
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paper_title: Impact Sound Pressure Level Performances of Basic Beam Floor Structures

paper_content:

In order to obtain reliable estimations of the impact sound insulation between rooms, it is necessary to know the acoustic performance of each element composing the floors. The contribution of the flanking transmissions, the attenuation of floating floors and the weighted normalized impact sound pressure level of the basic structure need to be determined in order to apply the simplified calculation method according to the EN ISO 12354-2 standard. With the aim of verifying the range of validity of the calculation method proposed by the EN ISO 12354-2 standard for typical basic beam floor structures, a research based on on-site measurements was conducted. This paper provides an analysis in terms of spectrum trend, predicted average weighted normalized impact sound pressure level and reduction of impact sound pressure level obtainable with a generic floating floor typology. The study can represent a starting point for a correct estimation of the impact sound insulation in new buildings and renovation plans.
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paper_title: Impulse response method for defect detection in polymers: Description of the method and preliminary results

paper_content:

The major problem encountered in the application of polymer industrial products is the difficulty of effectively modelling and predicting material performance and service life according to applied loads and operating environmental conditions. Furthermore, the presence of defects such as voids or inclusions created during manufacturing may affect the final performance. ::: ::: The aim of this study is to present and investigate the development of an innovative acoustic non-destructive technique (patent pending), able to verify defects into composite laminates. ::: ::: The analysis was carried out in two steps: the first aims to verify if distinct phases can be recognized within a material, while the second has the purpose of testing the proposed method on defective materials ad hoc prepared.
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paper_title: Assessment criterion for indoor noise disturbance in the presence of low frequency sources

paper_content:

Abstract Several studies have presented the effects of environmental noise in and around buildings and communities in which people live and work. In particular, the noise introduced into a building is mostly evaluated using the A weighted sound pressure level ( L Aeq ) as the only parameter to determine the perceived disturbance. Nevertheless, if noise is produced by activities or sources characterised by a low frequency contribution, the measurement of L Aeq underestimates the real disturbance, in particular during sleeping time. The international literature suggests methods to evaluate the low-frequency noise contribution to annoyance separately from the A weighted sound pressure level; almost all of the proposed methods are based on exceeding a threshold limit. This paper tests international criteria, by applying them in real-life indoor noise situations, and then analysing, comparing and contrasting results. Based on the result of the procedure above, a new criterion consisting of a single threshold is proposed, which simplifies the procedures in case of low-frequency components, but could be used for any situation.
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Title: Low Frequency Noise and Disturbance Assessment Methods: A Brief Literature Overview and a New Proposal

Section 1: INTRODUCTION
Description 1: Introduce the topic of low frequency noise (LFN), its impacts, and the limitations of existing assessment methods. 

Section 2: FREQUENCY RANGE AND THRESHOLDS
Description 2: Discuss various frequency ranges used in LFN assessment and the importance of thresholds in evaluation criteria.

Section 3: LOW FREQUENCY VS. INFRASOUND
Description 3: Clarify the distinction between low frequency noise and infrasound, and highlight different viewpoints on their classification.

Section 4: HEARING THRESHOLDS
Description 4: Explain how hearing sensitivity varies with age and the implications for LFN perception.

Section 5: HEARING VS. ANNOYANCE
Description 5: Examine the relationship between the perception of LFN and the annoyance it causes, including psychological factors.

Section 6: THE USE OF dB(A)
Description 6: Critique the use of the A-weighted sound pressure level as a measure of LFN disturbance and consider alternative metrics.

Section 7: DISCUSSION AND NEW PROPOSAL
Description 7: Present a discussion on the need for improved LFN assessment methods and introduce a new objective proposal based on robust measurement criteria.

Section 8: FINAL REMARKS
Description 8: Conclude with the significance of addressing LFN in noise assessments and the potential impact of the proposed method on future standards and legislation.