Abstract: A process and apparatus for selecting or designing a product, such as a muffler, having a complex, content-free sound output which is less stressful or more pleasing. The process includes the steps of sensing at least one physiological response of a subject (21) while the subject listens to an initial content-free sound output, repeating the sensing step for a new content-free sound output, comparing the physiological responses, and selecting the sound output for use in selecting or designing the product which output produces the physiological response that is the least stressful or most pleasing to the subject. The apparatus includes an audio playback device (15), a sound recording (16) of the initial sound, a sound recording (16) of the new sound, and physiological monitoring apparatus (17) suitable for attachment to and monitoring of the physiological responses of the test subject (21) to the playback of the sound recordings.

Abstract: A process and apparatus for selecting or designing a product, such as a muffler, having a complex, content-free sound output which is less stressful or more pleasing. The process includes the steps of sensing at least one physiological response of a subject (21) while the subject listens to an initial content-free sound output, repeating the sensing step for a new content-free sound output, comparing the physiological responses, and selecting the sound output for use in selecting or designing the product which output produces the physiological response that is the least stressful or most pleasing to the subject. The apparatus includes an audio playback device (15), a sound recording (16) of the initial sound, a sound recording (16) of the new sound, and physiological monitoring apparatus (17) suitable for attachment to and monitoring of the physiological responses of the test subject (21) to the playback of the sound recordings.

Abstract: A process and apparatus for selecting or designing a product, such as a muffler, having a sound output which is less stressful or more pleasing. The process includes the steps of sensing at least one physiological response of a subject (21) while the subject listens to an initial sound output, repeating the sensing step for the new sound output, comparing the physiological responses, and selecting the sound output for use in selecting or designing the product which output produces the physiological response that is the least stressful or most pleasing to the subject. The apparatus includes an audio playback device (15), a sound recording (16) of the initial sound, a sound recording (16) of the new sound, and physiological monitoring apparatus (17) suitable for attachment to and monitoring of the physiological responses of the test subject (21) to the playback of the sound recordings.

Abstract: A process and apparatus for selecting or designing a product, such as a muffler, having a sound output which is less stressful or more pleasing. The process includes the steps of sensing at least one physiological response of a subject (21) while the subject listens to an initial sound output, repeating the sensing step for the new sound output, comparing the physiological responses, and selecting the sound output for use in selecting or designing the product which output produces the physiological response that is the least stressful or most pleasing to the subject. The apparatus includes an audio playback device (15), a sound recording (16) of the initial sound, a sound recording (16) of the new sound, and physiological monitoring apparatus (17) suitable for attachment to and monitoring of the physiological responses of the test subject (21) to the playback of the sound recordings.

Abstract: A muffler (10) having a casing (21), an inlet opening (22) and an outlet opening (26). An initial partition (30) forms an expansion chamber (28). The casing (21) has mounted and formed therein a partition array (34) that includes a divider partition (36), a first intermediate partition (38), and a second intermediate partition (40). Partition array (34) is positioned in a main sound attenuation chamber (46). A collector partition (42) having a collector opening (44) is positioned between array (34) and opening (26). A pre-outlet chamber (48) is formed by collector partition (42) prior to outlet (26).

Abstract: A muffler assembly (10) for use with internal combustion engines discharging hot exhaust gases. The muffler assembly includes an elongated casing (15) having an inlet opening (12) at one end and an outlet opening (13) at an opposite end. A sound attenuating partition assembly including a conically converging, perforated, dispersion shell (33) and a transverse wall (45) are provided inside the muffler casing (15). The dispersion shell (33) tapers inwardly by an amount resulting a cross sectional area (A.sub.3) between the dispersion shell (33) and casing (15) at the transverse wall (45) which is at least equal to the area (A.sub.1) of the inlet opening (.sub.12). The combined area (A.sub.4) of the perforations (46) in the dispersion shell (33) upstream of the transverse wall (45) also is at least about equal to the area (A.sub.1) of the inlet opening (12). A perforated retaining shell (17) is provided positioned internally of the casing radially outwardly of the dispersion shell (33).

Abstract: A compact, high performance exhaust assembly (50) for an internal combustion engine (20) or the like having a balanced chamber (52). Two substantially parallel inlet exhaust pipes (38, 40) are mounted to a first wall (74) of the chamber (52) and are axially aligned with, but independent of, two output exhaust pipes (54, 56) similarly mounted to a opposing second wall (76) of the chamber (52). Exhaust gas is discharged through the inlet pipes (38, 40), preferably in an out-of-phase relationship or alternating from one inlet pipe to the other. The exhaust gas passes a short distance through the chamber (52) and out of aligned outlet pipes (54, 56). The majority of the exhaust gas flows directly through the chamber (52) without significant expansion. The exhaust assembly (50) increases the power output of the engine.

Abstract: A header assembly for an internal combustion engine including a pair of header pipes having discharge ends, a collector mounted on the discharge ends and having a housing directing exhaust gas pulses from both of the pipes to an outlet. The collector is formed to produce the flow of exhaust pulses in a manner fluid coupling out-of-phase exhaust gas pulses in each of the pipes to the others by an amount sufficient to increase horsepower of the engine at substantially all normal operating speeds. The header pipes proximate the inlet to the header collector are formed for discharge of gases along a common interface or boundary of substantial transverse length to effect fluid coupling. Additionally, the collector is free of channeling or protrusions to permit unconstrained transverse expansion of the pulses across the adjacent header pipe. A method of increasing engine horsepower by fluid coupling together header pipes also is described.

Abstract: A compact, sound-attenuating muffler for an internal combustion engine or the like. The muffler has a divergently tapered partition located near the inlet of the muffler for dividing the exhaust gases into two pulse streams with similar sound frequencies to achieve sound attenuation when the streams are converged back together. The diverging partition creates a low-pressure volume or region on the partition's downstream side where unignited fuels may accumulate. The partition is formed with a passageway to provide communication of live fire from the inlet of the muffler to the low-pressure volume for ignition of any unignited fuel. A method of communication of live fire from the inlet of the muffler to the low-pressure volume on the downstream side of the diverging partition in the muffler also is described.

Abstract: A compact, sound-attenuating muffler for an internal combustion engine is disclosed in which the muffler includes a stream dividing partition positioned proximate the inlet of the muffler to divide the incoming exhaust gases into two streams of substantially equal volume. The stream dividing partition directs the streams laterally of the inlet in directions diverging from each other, and the muffler sound-attenuating assembly further includes corridor defining partitions receiving the streams from the stream dividing partition and maintaining the streams in corridors as coherent substantially eddy-free streams. The corridor defining partitions further direct the streams laterally to converge towards each other for discharge of the coherent streams against each other from opposed directions in a common volume inside the muffler casing. Further sound attenuation is accomplished by a common channel receiving the streams after they are intersected or discharged against each other.

Abstract: A compact, sound-attenuating muffler for a high-performance internal combustion engine is disclosed in which the muffler casing has an elongated transverse cross-section with a height dimension of only slightly larger than the height dimension of the inlet exhaust pipe and a width dimension in the range of about 2 to 41/2 times the height dimension. The muffler includes a divergently tapering planar first partition which causes gases to be expanded only in a horizontal plane toward the side walls of the muffler and further includes a second partition formed to contract or converge the gases in a horizontal plane toward a central opening. The first partition has a cup-shaped back surface so that contraction of the gases around the back side of the first partition is highly effective in attenuating sound, and both partitions are sloped in a direction toward the outlet from the muffler so as to minimize the generation of back pressure, which is not substantially greater than the back pressure in a straight pipe.