Abstract: In order to provide a sound absorbing material superior in acid resistance, alkali resistance and sound absorbing quality and a sound absorbing layer using this sound absorbing material, multiple pieces of basalt yarn obtained by dissolving basalt to be continuous fibers are bundled by a fiber bundling agent to acquire a bundled material, and the bundled material is fibrillated to obtain a bulky sound absorbing material. Moreover, the sound absorbing material is arranged on the outer periphery of a perforated pipe constituting a muffler to form a sound absorbing layer.

Abstract: A muffler includes an outer box fitted over and attached to an exhaust pipe. The muffler also has a connecting member of a noncircular cross section fixed to said exhaust pipe and interposed between the exhaust pipe and the outer box.

Abstract: An exhaust muffler for use with an internal combustion engine has at least one internal suppression chamber, at least one inlet pipe for receiving exhaust gases from the internal combustion engine, and at least one outlet pipe vented to atmosphere. The exhaust muffler comprises a plurailty of component units connected in series with each other and each having the internal suppression chamber. Each of the component units has a casing having an inner layer of a sound-absorbing material which defines the internal suppression chamber, and a connector pipe connected to and extending through the casing, the connector pipe having upstream and downstream ends projecting out of the casing, the connector pipe having at least one opening which opens into the internal suppression chamber.

Abstract: A glass-wool mat is produced from a sheet of glass fibers by heating the surfaces of the sheet to a temperature close to the melting point of glass so that the glass fibers in the surface area have rounded ends and are shrunk so that they are firmly entangled together. Thus, non-irritating surfaces are provided on the mat.