Large vehicles, such as sport utility vehicles (SUVs) and minivans, exhibit body boom phenomena during multiple source excitation events including rough road/impact and power-train induced events. The main cause of the boom is the low-frequency acoustic/vibroacoustic standing waves (modes) of the cabin cavity being excited via the high acoustic transfer functions at multiple paths, due […]
Read MoreAn active boom noise control solution which can be viewed as a low-frequency ‘active tuned acoustic damper’ is developed to add acoustic damping to the low-frequency standing waves inside the cabin of a large SUV to quiet its tonal persistent boom noise. The existing stock 8 inch subwoofer as well as one of the […]
Read MoreProblem: Most rooms/cabins have dimensions that favor standing waves (resonant modes) which are in the range of vibration frequencies of the propulsion engines, gensets, or other machinery on board watercraft. undesirable and unfortunate coupling of the room acoustic modes with the machinery vibration frequencies results in boom/rumble in the room. such low-frequency noise, which is […]
Read MoreIn four stroke engines, including diesel engines driving generators, each cylinder fires every other revolution. This causes the engine vibration to occur at ½ the engine RPM, called the ½ order vibration, and its higher order harmonics namely 1 order, 1½ order, 2 order. In the case of a diesel generator, in addition to the […]
Read MoreTuned mass dampers (TMD) are highly effective and tunable passive vibration damping treatments. These devices are damped 2nd order systems appended to a vibrating structure; see Figure 1. Proper selection of the parameters (mass, stiffness, and damping) of a tuned mass damper, tunes the TMD to one of the natural frequencies of the underdamped flexible […]
Read MoreLarge vehicles, such as SUVs (Sport Utility Vehicle) and minivans, exhibit body boom phenomena during multiple source excitation events including rough road/impact and powertrain induced events. The main cause of the boom is the low-frequency acoustic/vibro-acoustic modes of the cavity being excited via the high acoustic transfer functions at multiple paths, due to an inherently […]
Read MoreReactive absorbers, such as Helmholtz resonators (HR) or quarter-wave tubes, are commonly used as the most effective solution for abating the low-frequency tonal noise in many applications including the quieting of air intake induction system noise in internal combustion engines. The problem with these low-frequency absorbers is their large size. In addition, reactive absorbers can […]
Read More