Category: 3. Noise and Vibration Control in Buildings

Structures such as buildings immersed in a moving fluid experience fluid loading forces. These forces are caused by several physical phenomena. The phenomena may be divided into three main categories: (i) steady incoming flow that impinges on the structure, (ii) unsteady incoming flow, and (iii) eddies (vortices) that form in the fluctuating wake flowing past…

Impact noise is other major sound transmission problem in buildings. Although transmission of airborne sound is probably the major problem, the secondary problem of sound transmission from impacts such as footsteps, doors slamming, hammering and other forms of construction, etc. has concerned acousticians for many years. Footsteps are the main source. There are two main…

When comparing different wall constructions, it is often convenient to use a single‐number rating instead of the complicated transmission loss (or normalized NR) which varies with frequency. Early single‐number ratings were obtained by simply averaging the TL (or normalized NR) in the frequency range of interest. Although such a system may be useful in rating walls, it…

It is difficult to obtain the idealized conditions of random incidence, diffuse sound fields, and absence of flanking transmission in laboratory situations. In real buildings (field conditions), such conditions are impossible to obtain in practice. However, as discussed before, it is sometimes necessary to determine the TL of a partition in the field where flanking transmission is present.…

There are several reasons for making sound transmission measurements, including: (i) to make tests under standardized laboratory conditions which should give repeatable comparisons of the performance of different partition structures and materials, (ii) to conduct laboratory tests in development work on partitions to indicate changes in sound TL which are caused by small design changes, (iii) to decide…

Leaks in a wall frequently occur in practice and are very serious. Unless great care is taken in construction, leaks will occur and the theoretical TL of a wall will not be achieved. This effect is particularly noticeable at high frequency where the TL of a wall would be expected to be high. In this region, a leak can…

Often partitions are composed of several different elements, such as a brick wall having windows and doors. The average transmission loss TLav of this composite structure can be calculated as follows: suppose τ1 is the transmission coefficient of element of area S1, etc. and that a diffuse reverberant sound field of intensity εc/4 (where ε is the energy density in the incident field…

12.4.1 Introduction Statistical Energy Analysis is often abbreviated to SEA. SEA was first used in the early 1960s to predict the vibration response of aerospace structures to acoustical environments and to determine the transmission of acoustical and vibrational energy in such structures [21–26]. Ungar, Eichler, Lyon, Maidanik, Smith, Scharton and Manning were some of the…

In order to achieve high TL with a minimum of weight, multiple panels with air spaces between the panels are usually employed. They are used in applications such as aircraft cabin walls and high‐rise buildings where weight savings are important. Higher TL is possible with a multiple‐panel than with a single‐panel partition (of the same mass per unit area),…

12.2.1 Mass‐Law Transmission Loss We will consider the case of a plane sound wave incident on a partition. For simplicity, we shall assume that the partition is thin (in wavelengths) and infinite in extent. For convenience, we assume that the x‐ and y‐axes are in the plane of the paper (see Figure 12.1) and that the direction of…