R.E. Halliwell

Design and commissioning of a new floor sound transmission facility

The pair of reverberation room that have been used at National Research Council Canada for about 30 years, are deemed too small by current ASTM standards. A new pair of rooms that incorporate some interesting ideas to satisfy the requirements and recommendations in both ISO and ASTM standards has just been constructed. One vertical cross section through each room is a five‐sided polyhedron. The test specimen is at one of the sides. This design allows the room volumes to be large (about 175 cm3 each), the specimen to be a normal size, and yet to be one complete surface of the room. The niche between the two room is minimal. Both rooms are resiliently supported as is the floor support. The upper room is of a lightweight construction and the lower is of poured concrete. Floors are constructed on wheeled, heavy concrete frames that can be moved in or out of the slot between the rooms. A crane outside the room allows other test frames with floors already constructed to be inserted into the specimen opening. So...

Influence of stud type and spacing, screw spacing, and sound absorbing material on the sound transmission through a double panel wall specimen

The work to be presented is part of a large series of measurements studying sound transmission through double panel walls. The wall surfaces in this work were of 16‐mm gypsum board. Studs of 38‐×89‐mm wood or 90‐mm light steel were used with spacing between stud centerlines varying from 30 to 120 cm. The spacing between screws used to attach the gypsum board was varied with the smallest separation used being 20 cm. Transmission loss was also measured for studless constructions. Transmission loss contours showed prominent dips at frequencies influenced by stud and screw spacing. Sound absorbing material added to the cavity had only a minor effect on these resonances suggesting that they are associated with panel resonances and not with the cavity between the panels. A selection of the data from this work will be presented and discussed.

The effect of stoplights on traffic noise

A study was undertaken to determine how the noise level due to free‐flowing traffic is affected by the insertion of a traffic light. Field measurements were taken at eight different traffic light locations, representing two configurations; that of two intersecting straight roads and tee junctions. A reference level, measured at a point where traffic noise was unaffected by the intersection, was used in conjunction with the NRC traffic noise prediction model to assess the change in noise level in the region about the traffic light.

Flanking sound transmission in wood-framed construction

This paper presents results from the first phase of a project to characterize flanking sound transmission at wall/floor junctions in wood‐framed constructions suitable for multifamily residential buildings. This phase of the study focused on the junction between a wood joist floor and a separating wall with two rows of 38×89‐mm studs. The objective of the study was to identify details that simultaneously provide good noise control and fire resistance. This paper presents the experimental approach and key results from the acoustical measurements. In addition to comparing how five common fire control solutions for the floor/wall junction affect the airborne and impact sound transmission, several generic retrofit modifications to reduce the structural noise transmission were tested. Parameters studied included the floor‐joist orientation (parallel or perpendicular to the separating party wall), and the type of subfloor (plywood or oriented strand board). The study has shown that suitable details can provide ...

Influence of sound absorbing material type and its location on the sound transmission through a double panel wall specimen

Sound absorbing material placed in the cavity of a hollow wall reduces the transmission of sound through the wall. The influence of density of commonly used materials, such as glass fiber, has been the subject of some argument. Also, it is sometimes thought that the position of the sound absorbing material in the cavity is important. The work to be presented is part of a large series of measurements studying sound transmission through double panel walls. Several types of glass fiber and mineral wool were placed in the cavity formed between two sheets of 3‐mm‐thick Lexan. Densities ranged from 10 to 145 kg/m3 and airflow resistivity ranged from 5 to 50 krayl/m. For the materials studied, the influence of material type on sound transmission class (STC) was small: only one or two points. The influence on transmission loss varied with frequency. Largest effects on transmission loss (changes of about 8 dB) were seen at the frequencies around 1000 Hz. The thickness and position of the materials were varied. Highest transmission loss was obtained when the sound absorbing material covered the entire inner surface area of the specimen. The same volume of material filling the cavity width but only partially covering the inner surface area, filling the lower half for example, gave lower transmission loss values.