Abstract: A sound absorbing muffler used to attenuate noise carried by the exhaust gases of an internal combustion engine includes a straight-through flow tube of constant diameter and cross-section. The muffler utilizes both reactive and dissipative components and includes two annular sound absorbing end chambers, an outer annular resonating chamber, and an inner sound absorbing means. The muffler's configuration produces effective noise attenuation, yet low backpressure.

Abstract: A sound absorbing muffler used to attenuate noise carried by the exhaust gases of an internal combustion engine includes a straight-through flow tube of cross-section having no baffles or flow reversals. The muffler utilizes both reactive and dissipative components and includes an outer annular resonating chamber and an inner sound absorbing chamber. The muffler's configuration produces effective broad band noise attenuation even at lower frequencies, yet low backpressure.

Abstract: This invention relates to sound attenuating mufflers, and more particularly to sound attenuating mufflers for dampening sound waves of various frequencies above a pre-selected cut-off frequency. Specially positioned acoustical insulation is provided to partially attenuate sound waves of a relatively low frequency. The insulation is carried in a chamber having one dimension of sound wave travel on the order of one-tenth the wavelength of a preselected cutoff frequency above which sound attenuation is desired. An adjacent chamber substantially free of insulation has one dimension of sound wave travel on the order of one-quarter wavelength of the cutoff frequency.