Mid high frequency volume source - Qmhf
The Qsources mid-high frequency Qmhf source is a general use monopole volume acceleration source with internal volume acceleration sensor. The volume acceleration signal ,from the flush integrated sensor in the nozzle, can be used for frequency response function measurements, or to determine the sound power which is inserted into the sound field. Isolation measurements, acoustic reciprocity, vibro-acoustic transfer sensitivity, experimental modal analysis, transfer path analysis, airborne source quantification, statistical energy analysis, sound field numerical model correlation, etc. etc.
The Qmhf volume source has become a standard in the vehicle industry. Noise or sound engineers in research, development and quality control are using this sound source. These sources are also used by vehicle NVH departments for validation of the high-frequency sound package of a vehicle body. To our knowledge every car/truck development center in the world has one or more Qsources Qmhf sources in use, and many suppliers as well.
But it is not exclusive to automotive applications, the sound source is also used on white goods, air-conditioning units, etc. Engineers appreciate the accuracy and speed with which the (reciprocal) transfer functions can be measured.
The volume acceleration signal provides a signal which is sensor is independent from the acoustic environment. The negligible diffraction makes it an accurate omni-directional sound source. And combined with the high output level, monopole radiation and wide frequency range, this source a versatile measurement device designed to meet the needs of noise and vibration research and development departments.
Features
Provides a high level of sound pressure with high-frequency monopole acoustic excitation
Minimal diffraction effects from the nozzle and tube with good omni-directionality
Supports efficient acoustic- and vibro-acoustic transfer function measurements, using reciprocity if needed
Highly suitable for airborne isolation testing, 150-12500 Hz in vehicles, railway, aircraft, white-good, encapsulations, etc.
Integrated volume accelertion sensors for a source level signal with long-time stable calibration
Modular tubes allow adapted frequency range and level
Measurement techniques
Airborne isolation
Airborne source Quantification or Transfer Path Analysis
Inverse source identification
(Vibro)acoustic Experimental Modal Analysis
Statistical Energy Analysis and equivalent
Numerical model correlation and improvement
Main characteristics
Diameter +- 30 mm, high output level
Real Time volume acceleration signal
Power 109 db Lw white noise
Core frequency range 200-6300 Hz*
Extended frequency range 150-12500 Hz**
Accessibility
The Qmhf 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 pressure levels.
