Compact Volume Source - Qmed
The Qsources Qmed compact volume source has been developed to measure acoustic and vibro-acoustic transfer functions in and around vehicles. The unique combination of ring radiator and long stroke piston design allow sufficient level at low frequencies and negligible diffraction makes it an accurate omnidirectional sound source up to 1600 Hz.
This source also allows you to measure typical vibroacoustic body noise transfer functions reciprocally, which is valuable information for vehicle body development. It can excite the passenger and trunk cavity to measure scaled acoustic transfer functions. These frequency response functions (FRFs) can be used to perform acoustic modal analysis. These sources are compatible with the latest standards for acoustic modal analysis, which propose multiple sources in the cavity without the disturbances associated with traditional low-frequency sources.
Aircraft cabin, agricultural tractors, vehicle NVH, applications cover the needs of for accuracy in product development and research. Placed in a car cabin, the acoustic transfer from 5 Hz to 1600 Hz can be measured, or for a vibro-acoustc transfer function 30 to 1600 Hz is realistic. Scaled reciprocity transferfunction measurements and experimental vibro-acoustic modal analysis of cavities/cabins/fuselage is a frequent application.
The reference sensor is integrated in the source and measures the volume displacement. The volume displacement (or volume acceleration) sensor is independent from the acoustic environment in which the source is used, and stable in time requiring re-calibration only once year or once every two years depending on the users requirements.
Features
Compact volume acceleration sound source
Built for scaled acoustic driven frequency response functions
Near to perfect monopole behavior due to patented ring radiator configuration
Drivers and integrated sensors for a source level signal with long-time stable calibration
Large stroke piston drivers for high sound pressure level in smaller spaces, between 5 and 1600 Hz
Highly suitable for reciprocity based vibro-acoustic frequency response function measurements in cars, truck cabins, etc. for the 20 to 1600 Hz range
Built-in thermal and electrical overload protections
Measurement techniques
Transfer Path Analysis
Inverse source or load identification
Vibro-acoustic modal Analysis
Statistical Energy Analysis and equivalent
Numerical model correlation and improvement
Main characteristics
Real time volume acceleration proportional output signal
Diameter +- 68 mm, length 200 mm
Sound power 103 db Lw, non-equalized white noise
Core frequency range 30-1000 Hz*
Extended frequency range 5-1600 Hz**
Availability
The Qmed compact volume source is marketed in cooperation with Siemens under the Simcenter Qsources product line
*What is core frequency range for sound sources?
In the core frequency range a close approximation of omni-directionality and high output can be expected. Or in case of sources for ISO standard regulated requirements, like for building acoustics applications, the source will be well within the ISO requirements.
**What is extended frequency range for sound sources?
In enclosed spaces, a limited low frequency output from a source is not necessarily a limitation for measurement effectiveness or accuracy. Still in an open sound field, or very large enclosed space, the same source level may not generate sufficient sound pressure level at the lowest frequencies. Low frequency extension range is typically for smaller volume spaces like a car cabin, or an aircraft cabin.
The high frequency extended range is typically used when absolute omni-directionality is not needed or not feasible at the required sound pressure levels.