HT instruments HT157 - Manual (Page 15)

HT155 - HT157
EN - 13
5. CARRYING OUT MEASUREMENTS
The instrument is capable of carrying out different types of analyses of the sound pressure
level of a noise source:
1. Statistic analysis of noise
2. Spectrum analysis of noise with octave-band filter (1/1) (HT157 only)
3. Spectrum analysis of noise with third-octave band filter (1/3) (HT157 only)
For simplicity, the following descriptions are referred to the instrument model HT157
5.1. STATISTIC ANALYSIS OF NOISE
5.1.1. INITIAL OPERATIONS
1. Turn on the instrument by pressing the “ ” key. The screen for the selection of the
analysis type is shown on the display for approximately 5s (see Fig. 10)
Fig. 10: Initial screens of statistic analysis
2. Use the keys “ ” and “ ” the option “Stat.Analyzer (00101)” and confirm with “ ”.
The instrument shows the main menu of the statistic analysis, consisting of 6 icons on
the display
3. Select the relevant icon and press “ ” to enter the specific menu. In detail:
 Statistic  the instrument measures the sound pressure level with weighting “A”,
with time constant Fast and equivalent noise level
 24 Hours  measurement of the sound pressure level in a fixed time period of 24
hours
 Integral  the instrument integrates the sound pressure level in the three frequency
weightings (A, C, Z) and in the three time constants (Slow, Fast, Impulse)
 Data  Section which contains the data of the recordings saved with the instrument
(see chapter 7)
 Setup  allows accessing the instrument’s programming menu (see § 4.6)
 Calibrate  section in which it is possible to calibrate the sensitivity level of the
microphone by using the provided portable calibrator HT151 (see § 6.1.3)
4. The indication next to the icon “ :XXX” in the right-hand top part of the display
indicates the number of the group of the datum which can be saved in the instrument’s
memory