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Flachlautsprecher

Measurement of Loudspeaker Systems and Components

Measured parameters

Measurement objects

Measurement equip-

ment

The proposed services include standardized test methods as well as specialized and

custom designed procedures. For these, we offer highly sophisticated laboratories

and test facilities.

Acoustical: Sound pressure level, frequency response, phase response, group delay, step res-

ponse, impulse response, waterfall diagram, harmonic distortion, intermodulation distortion,

maximum SPL at predefined THD, radiation pattern (isobar, polar, balloon plot)

Electrical: Electrical impedance, Thiele&Small respectively Klippel parameters (LPM/LSI), trans-

mission behavior of loudspeaker controller (frequency response, THD, inherent noise, etc.)

Optical: Vibration displacement, velocity and acceleration of surfaces like membranes or en-

closure walls

Loudspeaker chassis (from micro speakers to public address woofers), loudspeaker systems,

loudspeaker cabinets, loudspeaker arrays, headphones, alarms, loudspeaker electronics,

transducer systems, vibrating surfaces

Anechoic chamber, measurement system Monkey Forest with robot ELF, Klippel R&D System

with Scanning Laser, Polytec PSV 400 Laser Scanning Vibrometer, Soundbook with SAMURAI

software from Sinus Messtechnik, measurement system MLSSA, measurement system EASERA,

Rohde & Schwarz Audio Analyzer UPL and UPD, Cortex MK2 artificial head, Bruel & Kjear

turntable system, cableway for measurement microphones from Norsonic, standard baffle (DIN

45575), measurement microphones from MT Gefell and structure-borne sound sensors from

Metra

Amplitude frequency response

100 1,000 5,00060

65

70

75

80

f/Hz

SPL/ d

B

0◦

15◦

30◦

45◦

Acoustic Measurements in the anechoic chamber

Vibrational behavior of a loudspeaker

Membrane excursion over frequency

100 500-2

-1

0

1

f/Hz

X/ m

m

3.0 V2.2 V1.3 V0.5 V

Force factor over membrane excursion

-2 -1 0 1 20

1

2

X/mm

Bl/

N/A

Bl(X)Bl(-X)

Left: example of radiation pat-

tern at 0°, 15°, 30° and 45° in

the horiz. plane.

Right: example of harmonic

distortion (THD, k2, k3, k5) at

constant input voltage over

frequency.

Left: example of membrane

respectively voice coil excursion

at different input voltages

Right: example of force factor

as a function of membrane res-

pectively voice coil excursion.

Example of mode shapes of a

loudspeaker membrane at dif-

ferent frequencies (left: 400 Hz,

middle: 2.9 kHz, right: 7.8 kHz)

with increasing partial vibration.

Harmonic distortion over frequency

100 1,0000.001

0.01

0.1

1

10

f/Hz

THD/ %

k2k3k5

THD

Harmonic distortion over frequencyAmplitude frequency response

Force factor over membrane excursionMembrane excursion over frequency

Measurement of an electrodynamic loudspeaker driver

Fraunhofer Institute for

Digital Media Technology IDMT

Ehrenbergstr. 31

98693 Ilmenau

Germany

Contact Person

Dr.-Ing. Daniel Beer

Phone +49 3677 467-385

daniel.beer@idmt.fraunhofer.de

www.idmt.fraunhofer.de