Tailpipe and Inlet Noise Simulator (TINS)
The Tailpipe and Intake Noise Simulator (TINS) has been developed to allow the noise transfer functions to be measured reliably from the tailpipe and inlet orifices to both vehicle interior and exterior microphones.
Unlike the ISVR omni-directional sources, the TINS attempts to reproduce the directivity pattern of sound radiating from the end of a pipe. By using representative pipe orifice geometry and dimensions, an approximation of the directivity pattern of the real exhaust outlet or intake orifice may be achieved. Typically the low frequencies are omni-directional whereas the higher frequencies exhibit the local directivity patterns seen with the real systems.
By adopting standard microphone locations for the orifice source strengths as well as the vehicle interior and exterior noise, Pressure to Pressure (P/P) transfer functions may be easily and reliably measured without any complex calibration of the TINS. Typically the source microphone locations are at 100 mm from the intake orifice and 500 mm from the exhaust tailpipe outlet; while interior noise is measured at the driver’s or passenger’s head position and exterior noise is measured at the standard 7.5 metre drive-by distance.
The output from the TINS is very dependent upon the test configuration, as the adopted pipe work has considerable influence upon the sound level and spectrum character.
The graph on the right shows the output from the TINS without any pipe work as measured at 1 metre on axis when driven at nominally 6 dB below its maximum.
The TINS may be driven by the ISVR universal noise generator/amplifier
or by an appropriate signal generator and amplifier.