BRUEL & KJAER HATS 4606, User Manual

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APPENDIX B
Glossary
53
EEP-DRP
The sound pressure measured by the ear simulator is referenced to the ear-drum
reference point (DRP). The transfer function provided on the data disk will be used for
converting data to the ear canal entrance point (EEP), when it is required to compare
results with specifications based on measurements referred to EEP.
Frequency
The number of pressure variations per second. Frequency is measured in hertz (Hz).
The normal hearing for a healthy young person ranges from approximately 20 Hz to
20000 Hz (20 kHz).
Frequency weighting
Our hearing is less sensitive at very low and very high frequencies. In order to account
for this, weighting filters can be applied when measuring sound. The most commonly
used weighting is the ‘A-weighting’, which approximates the human ear’s response
to low – medium noise levels.
A ‘C-weighting’ curve is also used, particularly when evaluating very loud or low-
frequency sounds.
HRP HATS reference point. The point bisecting the line joining the ear canal entrance
points (EEPs).
LFR Listener free-field frequency response. The difference, in dB, between the third-
octave spectrum level of the acoustic pressure at the ear-drum reference point (DRP)
and the third-octave spectrum level of the acoustic pressure at the HATS reference
point (HRP) in a free sound field with the HATS absent (test point).
Lip plane The lip plane on HATS is normally different from the plane of the mouth simulator
orifice. The lip plane is vertically oriented when HATS is in the reference position.
Mouth simulator A device consisting of a loudspeaker mounted in an enclosure and having a directivity
and radiation pattern similar to those of the average human mouth.
000055
Frequency
(Hz)
0
Lp (dB)
10 20 50 100 200 500 1k 2k 5k 10k 20k
–20
–40
–60
A
C