Low-Mid frequency volume acceleration sound source

Volume acceleration sound sources are sophisticated acoustic excitation devices, capable of producing high levels of sound or noise as well as an accurate real time signal the acoustic output. Our low-mid frequency source, the E-LMFVVS, covers the 20 to 800 Hz frequency band, although a special version for 25 to 1000 Hz can be made on request.

This source is typically used for cabin vibro-acoustic modal analysis, TPA analysis of structure borne or airborne contributions, Frequency Based Sub-structuring, etc.

If you think this sound source looks like a dummy, you are right. The E-LMFVVS was deliberately made to imitate the acoustic properties of a person at low frequencies. And because most applications are for seat positions, the device is optimized for quick positioning on a seat with the active center at ear location.

The unique properties of this low-mid frequency source include compact, human body diffraction simulation, omni-directional, time stable calibration, high noise levels. These features make this device extremely accurate and efficient for the analysis of transport vehicles like cars, vans, trucks, busses, trains and aircraft.

General Functionality:

Point source for accurate acoustic excitation
Real-time volume acceleration output signal
Output volume acceleration sensor integrated and environment and time stable
High volume displacement level at compact size
High acoustic impedance
Human body diffraction simulation (50% male)
Sound field excitation from the left or the right ear location
Useful frequency range 20 to 800 Hz nearly constant noise spectrum
Constant sensitivity value of the output signal
Omni-directional point source at ear location
Human body diffraction simulation
Easy to position on a seat

Technical specifications

Size, maximum external dimensions: 0.245*0.380*0.790 m
Size, shipping dimensions: 0.245*0.380*0.545 m
Weight excluding cable: 17 Kg
Effective frequency range: 10 to 800 Hz
Constant real-time output signal freq. Range: 10 to 800 Hz, +-2 dB
Output volume acceleration sensitivity: 22 m3/s2V nominal
Output signal conditioning requirement: ICP
Free field omnidirectionality freq. Range: 10 to 150 Hz, +-3 dB
Omnidirectionality with diffraction**: 10 to 800 Hz, +-3 dB
Source input impedance: 18 Ohm nominal
Required signal output impedance: 10 KOhm
Maximum input current: limited by a F1A fuse
Minimal power amplifier requirement: 150 Watt and 36Volt (RMS)
Maximum volume displacement ***: 0.0022 m3 (RMS)
Maximum sound pressure level in semi free field***: 96 dB SPL at 1m

Note: Performance and dimensions of the device, as stated above, are an indication only. The actual values of the delivered product can deviate from the given specification. However, in most of such cases the specifications will exceed the given ones above, because of improvements in the used materials and design.
** Omnidirectionality relative to an omni-directional point source at ear location on a human body.

*** When using continuous broadband random noise 20 to 800 Hz, of low crest factor.

Applications

Vibro-acoustic modal analysis
Mostly used in cabins of cars, trucks, train, and aircraft, but sometimes in other locations like the engine compartment, or the space underneath a vehicle. Typical instrumentation for modal analysis includes Scadas III : 16 channels or more, two E-LMFVVS on two seats, several microphones in the cabin space and several accelerometers on the body panels and structure. The software includes F-mon, acoustic modal, and modal design.With this method you get scaled modal models, a level very fast instrumentation, and can attain a high excitation.

Vibro-acoustic Transfer Path Analysis
Mostly used on suspension systems of cars and trucks, but sometimes on aircraft, trains, stationary machinery, etc. Typical instrumentation includes Scadas III : 16 channels or more, two E-LMFVVS on two seats and a large number of accelerometers at the suspension supports. The software used is F-mon, TPA and RMA.

Apart from fast instrumentation, you can expect more then sufficient excitation, efficient parallel measurements and a large number of vibro-acoustic FRF.

ASQ, panel contribution analysis
Used mostly on cabins of cars and trucks, sometimes on trains, aircraft, machinery, and defense material. Typical instrumentation includes Scadas III; 16 channels or more, two E-LMFVVS on two seats and a large number of accelerometers on all cabin panels. Typical software used for panel contribution analysis is F-mon, TPA, and RMA.

Advantages include more than sufficient excitation, fast instrumentation, efficient parallel measurement of a large number of acoustic FRF.

ASQ, source contribution analysis
Mostly used on drive-lines and power-trains of cars and trucks, but sometimes used on exhaust systems, intake systems, tyres/tires, etc. Typical instrumentation includes Scadas III: 16 channels or more, two E-LMFVVS on two seats, and a large number of microphones on all potential sources. Typical software includes F-mon, TPA, and RMA.

Advantages include more than sufficient excitation, fast instrumentation, efficient parallel measurement of a large number of acoustic FRF.