The future demands for building ventilation are likely to have an impact on the susceptibility of buildings to the ingress of external noise. Maximizing building natural ventilation can be an attractive goal but care should be taken to consider such factors as exposure to road noise. Climate projections give information about changes that could occur over the next 90 years, this is a time scale relevant to buildings. It would seem appropriate to quantify the benefits and challenges of noise control strategies in terms of ventilation rates and energy over the life time of a building. In this research whole building ventilation and energy use during the summer months was investigated with building energy modelling. Opening characteristics were adjusted according to noise levels at the façade given by noise mapping. The effect of noise control strategies on ventilation and energy modelled with weather data representing the current day was compared with that representing the future according to the latest climate

This work looks at using coherent averaging to measure transducer responses with high precision without using an anechoic chamber. The use of coherent averaging in building acoustics is familiar to those who use deterministic signals (e.g.. MLS) as the basis for their measurements. The primary concern is to achieve a sufficient signal to noise ratio so that results relate to the system being measured rather than unrelated noises. This technique requires conditions to be unchanging with time but coherent averaging can be used to advantage in situations where conditions are purposefully rendered time-varying. It is possible to select or reject contributions to a measurement by choosing some transmission paths to be time invariant and making others – ones we wish to remove from the measurement - varying. In previous work we have shown that by rotating a loudspeaker-microphone couple in a highly reverberant room we can measure the loudspeaker (or microphone) transfer function with the same accuracy achievable in an anechoic chamber by using this technique to suppress the reverberation in the room. In this more recent work we consider whether any particular deterministic signal – e.g. A log ‘chirp’ – is more advantageous for this application and whether the availability of the new soundfield-type microphones offers an improved way for making such measurements.

In order to obtain reliable estimates 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.

Contrary to common belief, a relatively simple and practical lightweight timber based floor/ceiling can have impact sound insulation superior to that of concrete slab based systems. This paper presents examples of such systems that include vibration isolation/damping features, such as rubber ceiling batten clips, glass fibre wool, and a sand-sawdust mixture layer. We give enough details to reproduce our experiments and build the proposed lightweight systems.

The Lombard Effect continues to breed noisy spaces, and as the current trend towards open plan spaces (particularly offices and classrooms) continues, understanding this effect so we can predict activity noise levels in reverberant spaces becomes all the more crucial. In this paper, we review previous work on experimental testing of the Lombard Effect in children and adults and the resulting prediction model.  We highlight the limitations and unexpected outcomes of that work and investigate a new testing method that will lead us towards more robust real-life Lombard Effect data, which can be used to refine our prediction model.

Echolocation is a genuine human ability that is closely related to localization of reflected sounds. It is part of the scarcely studied and promising field of the percepto-cognitive processes involved in everyday audition of non-verbal sounds. It implies the use of self-generated sounds (original or direct signal) with the specific purpose of obtaining auditory information (reflected signal) to locate and recognize unseen silent objects. This ability turns out to be crucial for the achievement of the independent mobility of the blind person, an aspect that is severely affected by blindness. During the 40’s a rigorous research program was put forward in order to elucidate the sensory basis of echolocation. A series of ingenious tests was designed in which tactile or auditory input was artificially suppressed, one at a time. None of the subjects was able to perceive the object in the last case. Later studies inquired into the discriminatory aspects of echolocation and two auditory fusion phenomena, repetition pitch and the precedence effect, have recently been postulated as possible underlying psycho-acoustic mechanisms. According to the new cognitive and ecological paradigms in perception, it is assumed that the primary function of the auditory system is to determinate (to localize and recognize) the characteristics of the sound source through the sounds emitted by it. Within this context, it has been argued that echolocation is a variant of that general process. Two recently established scientific paradigms have enriched the study of this ability: the sensorimotor contingency theory and the sensory substitution perspective. We present a brief historical revision of the main studies that have been carried out on this particular phenomenon, our own included, with special emphasis in its treatment within the context of embodied cognition theories.

The New Zealand Wind Turbine Standard NZS6808 provides guidance on the methods for the prediction, measurement and assessment of sound emissions from wind turbine generators. This study attempted to quantify the potential variability between measured wind turbine generator sound emissions using the descriptors LAeq and LA90 [specified in the standard], both on the wind farm site [near-field] and at a remote receiver dwelling location [far-field] where people reside. Results of the field study showed that the mean sound level difference between the descriptors, measured at a residential location remote from the wind farm was 2.4 dB compared to 1.4 dB on the wind farm site. Of the 11,150, 10 minute sound pressure level sample pairs recorded over a 12 month period at the remote location, only 39 remained for the analysis after post-filtering to remove samples contaminated by extraneous noise. The study illustrates the difficulty in making robust measurements of wind turbine sound in the far-field.

Numerical simulation is widely used in product design for different purposes ranging from structural modelling, FEM analysis, vibroacoustics to multi-objective design optimisation. Unfortunately, its application to Sound Quality is still extremely limited. This paper describes the use of a multi-objective optimisation code aimed at identifying noise control solutions which can improve the sound quality at the operator station of earth moving machinery during real working conditions. In a previous study the case of stationary noise signals was analysed and a multi-objective genetic algorithm was used to find the modifications in the input spectrum which led to the minimization of the time-averaged values of loudness and sharpness. In this paper the optimisation algorithm was modified to be applied to time-variant noise signals, characteristic of real working conditions. New input variables were identified to describe the time variant characteristics of the input signals and a numerical code was developed according to the DIN-45631/A1 procedure in order to properly calculate the loudness parameter of time-variant sounds. The new multi-objective genetic algorithm was finally applied to different noise signals recorded at the operator position of loaders in working conditions, with the purpose to find the modifications in the input system which minimised the percentile values of loudness and sharpness parameters. The results confirm the significant link between sound quality condition and frequency content of the noise signals, making it possible to evaluate the spectral variations needed to obtain psychoacoustic improvements.

Numerical simulation is widely used in product design for different purposes ranging from structural modelling, FEM analysis, vibroacoustics to multi-objective design optimisation. Unfortunately, its application to Sound Quality is still extremely limited. This paper describes the use of a multi-objective optimisation code aimed at identifying noise control solutions which can improve the sound quality at the operator station of earth moving machinery during real working conditions. In a previous study the case of stationary noise signals was analysed and a multi-objective genetic algorithm was used to find the modifications in the input spectrum which led to the minimization of the time-averaged values of loudness and sharpness. In this paper the optimisation algorithm was modified to be applied to time-variant noise signals, characteristic of real working conditions. New input variables were identified to describe the time variant characteristics of the input signals and a numerical code was developed according to the DIN-45631/A1 procedure in order to properly calculate the loudness parameter of time-variant sounds. The new multi-objective genetic algorithm was finally applied to different noise signals recorded at the operator position of loaders in working conditions, with the purpose to find the modifications in the input system which minimised the percentile values of loudness and sharpness parameters. The results confirm the significant link between sound quality condition and frequency content of the noise signals, making it possible to evaluate the spectral variations needed to obtain psychoacoustic improvements.

The relationship between noise and affective response is not well understood, and there have been calls for further physiological investigation. To investigate subjective responses to noise, an attempt is made here to analyze the auto-correlation function of alpha activity during the presentation of annoying sounds. Twelve real-world sounds (e.g. baby’s cry, snoring) were presented to a small sample (n = 16), who listened while having their scalp potentials recorded. Noise sensitivity questionnaires were used to assess participants’ sensitivity to noise in general. Findings indicate that those who are noise sensitive appear easily aroused by noise regardless of the magnitude of annoyance. In contrast, participants who classified as noise resistant are typically aroused only when the most annoying sounds are presented. Theses result suggests a difference in processing between the noise sensitive and the noise resistant individuals. The current investigation may provide a basis for future studies to evaluate the underlying neural processes associated with noise annoyance.

It is useful to have an efficient method to determine the sound field in a room produced by a source that is not omnidirectional. A method is thus developed for simulating a “higher order” source with an arbitrary directional pattern in a reverberant room. Several types of directional sources are subsumed by the higher order source, including an arbitrarily vibrating cylinder and an array of vertical line sources arranged on a cylinder. The sound field is calculated by extending the image-source method. For simplicity the sound is modelled in 2-D where sources are either tall or have an infinite vertical extent. A modal expansion of the sound field is used, which reduces the computation of calculating the sound field over a large number of points. The method is particularly suited to array signal processing where the sound field is sampled at multiple points. Efficient algorithms are presented for simulating both circularly-shaped regions absent of sound sources and the entire room.

Historically timber-framed floor system designs have sometimes included some sort of granular material infill in order to reduce sound transmission between tenancies. Often this material is readily available and low cost material (e.g. ash, scoria, and sand). Recent research has been conducted into timber-framed floor toppings which contain a granular material infill in the form of a sand and sawdust mixture. The sand and sawdust infill increases the mass of the floor, which improves the low frequency impact insulation performance. This sand and sawdust infill also greatly increases the vibration damping in the upper part of the floor, improving the mid to high frequency sound insulation performance, while also making the system robust to construction defects. This paper presents results of isolated element impact insulation and flanking transmission measurements of timber-framed floors which have a sand and sawdust infill in the floor topping.