THE ACOUSTIC PRINCIPLES ARE PRESENTED FOR ATTENUATING AUTOMOBILE ENGINE NOISE. THE VARIOUS ASPECTS OF SOUNDPROOFING EXHAUST NOISE ARE DISCUSSED, ALONG WITH THE MEANS FOR LOW PITCH SOUND ABSORPTION. A TERMINAL REFLECTION MUFFLER SYSTEM FOR TOTAL NOISE SUPPRESSION IS DESCRIBED. AN ADMITTANCE TYPE MUFFLER IS ALSO CONSIDERED, AND THE REQUISITE DYNAMIC AND ACOUSTIC CONDITIONS FOR ITS USE ARE DETERMINED. DIFFERENT MATERIALS ARE PROPOSED FOR USE AS SOUND ABSORBERS AND THE CASE OF ACOUSTIC SUPERCHARGING AND OPTIMIZATION IS STUDIED.