Norsonic nor140, Instructional Manual, Page: 58 / 220

40
Chapter 6
Basic time profile measurements
The time profile is no less than an electronic level recorder!
Basic time profile
measurements
Instruments equipped with the optional extension 6,
level vs. time will be able to log the time profile like the
classic level recorders used to do.
The time profile is measured by dividing a total
measurement into smaller periods of time, all hav-
ing the same duration. Extension 6 allows the period
length to be from 1 second and upwards in 1 second
steps, while the enhanced profile (the optional exten-
sion 7) allows a period length from 25 ms and upwards
in 25 ms steps (but in 1 second steps above 1 second
period length).
The logged profile may be transferred to a PC for
further analysis. Software like Nor1026 NorReview may
be used for extensive analysis of the result.
Global vs. profile
The traditional sound level measurement and the fre-
quency analysis both consider the entire measurement
as a whole without dividing it into smaller parts. One
may therefore consider these two measurements as
global measurements, while the level vs. time meas-
urements represent the
profile
.
In the display, the global measurements are denoted
Σ
(pronounced sigma) while the profile measurements
are denoted Δ (pronounced delta). To switch between
the modes, just press the Σ↔Δ key.
The L
eq
, L
MAX
and L
MIN
are measured for every pe-
riod separately and stored in a buffer. All functions are
A-weighted apart from the peak level which can be set
as C-or Z-weighted. The enhanced profile (ext. 7) pro-
vides more options – see Enhanced profile measure-
ments.
Profile measurements may be made in parallel with
global frequency analysis (filters are optional) and
in parallel with the traditional sound level measure-
ment described in the chapter Simple sound meas-
urements. If your Nor140 is equipped with the multi-
spectrum extension, you may log the spectrum as a
function of time. See
Multispectrum measurements
for
more on this.