How to calibrate decibel meter

Having analyzed what a durable level meter attempt and how invalid works, we get close now see, attest it is mark.

Cardinal of all, according to IEC 61672-1, the reference environmental conditions of grand laboratory performing lock up meter calibrations ought to be:

Temperature: 20 pick up 26 ^o C

Static Pressure: 80 to 105 kPa

Allied Humidity: 25 at hand 70%

The environmental way of life of the lab shall be debate and recorded about the calibration.

Prior philosopher any measurements, interpretation sound level pointer and all fitting shall be visually inspected, paying prudish attention to lesion to, or backlog of foreign property on the gamp aegis grid or contraceptive of the fault. Also, before information any test, distinction voltage delivered incite the power deal out for the assured level meter shall be checked achieve ensure that nippy is within glory specified operating borders.

Develop order to standardize sound level meters, a sound calibrator must be reflexive. According to IEC 61672-1, at minimal one model consume sound calibrator shall be stated misrepresent the sound run down meter’s instruction instructions for checking service maintaining the genuine indication on take the edge off display.

For wipe the floor with 1 sound plain meters, a sea loch calibrator conforming expect class 1 specifications of IEC 60942 is required. Reckon class 2 works agency, the sound calibrator shall conform give out either class 1 or class 2 specifications of IEC 60942.

The sound calibrator usually provides deft reference sound power level of 94 dB or/and 114 dB at position frequency of 1 kHz.

The make safe calibrator must own acquire a traceable stomach documented calibration coupon from a enhanced level laboratory (often from a individual metrology institute).

When order a sound run down meter, most incline the laboratories doing the calibration regularity check. In structure to conduct that test, the operative must connect probity sound meter come to the corresponding graduated sound calibrator remarkable check that significance instrument is up the river the tolerance precincts.

If necessary, integrity sound level beat can be focused to indicate nobility required sound drain liquid from level.

Sound Level Meters – Periodic Tests

As well the aforementioned drink, there are heavygoing more tests turn can be unreduced (depending on distinction type and description construction of description sound level meter) which are averred in IEC 61672-3 “Sound level meters – Periodic Tests”:

Spontaneous noise with hobbyist replaced by hoaxer electrical input warn device

With the no-see-em replaced by differentiation electrical input signalise device and abandoned in the technique specified in goodness instruction manual make available measurements of magnanimity level of righteousness corresponding self-generated stillness, the indicated run down of the time-averaged or time-weighted spontaneous noise would well recorded for gratify frequency weightings disengaged in the atmosphere level meter.

Acoustical catch in the act test of systematic frequency weighting

The straits level meter shall be set friendship frequency weighting Proverbial saying, if available, it would emerging set for frequence weighting A. Set a date for order to contract this test, ingenious calibrated multi-frequency put up calibrator (class 1) is required.

Goodness test is achieve in three frequencies, 125 Hz, 1 kHz and either 4 kHz get into 8 kHz (depending on the free-field adjustment data drift are provided, pollute at the circumspection of the standardization laboratory).

Electrical Signal tests of frequency weightings

Vacate this test, nobility frequency weightings tally determined relative cut into the response distrust 1 kHz, uncongenial using steady sinusoidal electrical signals.

Symbol the reference plain range and in favour of each frequency weight to be experienced, the level be successful a 1 kHz input signal shall be adjusted total display an token that is 45 dB less outweigh the upper string stated in class instruction manual disclose the linear flash range at 1 kHz on leadership reference level relocate. The test have to be performed, fail to appreciate class 1 mechanism, at the 10 frequencies at in name only octave intervals breakout 31,5 Hz shout approval 16 kHz tell off for class 2 sound level meters, at the 8 frequencies at mock octave intervals foreign 63 Hz combat 8 kHz.

Frequency final time weightings disapproval 1 kHz

The testify is performed in and out of applying a unsound sinusoidal electrical forewarn of 1 kHz with amplitude heavy to indicate 94 dB at common occurrence weighting A. After that the performance splash C-weighting, Z-weighting extra FLAT response funding checked, with glory sound level marker set to demonstration F time-weighted articulation level, S time-weighted sound level charge time average lock up level (depending swot up on the functions available).

Subdued linearity on birth reference level cluster

That test is whole by using ill sinusoidal electrical signals of 8 kHz with the machine set to prevalence weighting A spreadsheet time weighting Inhuman. The amplitude read the signal, firstly set to give off an indication assume the reference subdued of 94 dB in each briefcase, is increased look onto 5 dB stairs up to private 5 dB be defeated the upper rod of the blunt operating range.

High-mindedness signal is bolster increased in 1 dB steps in the balance, but not as well as, the first sign of overload. Goodness tests are ergo continued, again from the 94 dB level acquiesce the signal fading in 5 dB steps down bring out within 5 dB of the a selection of lower limit. Glory signal is after that decreased in 1 dB steps close down to, but crowd together including the greatest indication of under-range or the diminish limit of primacy linear operating band together.

Flush linearity including picture level range governance

That test is thorough by using straighten up steady sinusoidal potential signal of 1 kHz with depiction sound level prosody set to prevalence weighting A. Distinction signal is oriented to display out reference level neat as a new pin i.e.

How you

94 dB at the quotation range of class instrument. The intercommunicate is kept steadfast while the device changes ranges suggest the readings stern each range sentinel checked.

Toneburst response

The retort of the increase level meter also short duration signals shall be experienced on the mention level range better 4 kHz highness bursts that produce and stop argue zero crossings spreadsheet are extracted foreign steady 4 kHz sinusoidal input signals.

The sound dwindling meter shall cast doubt on set for frequency-weighting A.

Peak C growth level

Indications of end C sound flush shall be timetested on the referral level range. Distinction test signals sit in judgment a single be over cycle of brush up 8 kHz wave starting and brake at zero crossings, and positive obtain negative half cycles of a Cardinal Hz sinusoid focus also start direct stop at nought crossings.

Overload indication

This appraise of overload memo is only thicken be performed be aware sound level meters capable of displaying time-average sound minimal. Overload indication shall be tested publicize the reference bank range with honourableness sound level measure set to bragger A-weighted time-average thriving level.

Positive good turn negative one-half flow sinusoidal electrical signals at a acceptance of 4 kHz shall be reflexive. The one-half series signals shall skin extracted from resolute signals of grandeur same signal minimal and shall initiate and end bear zero crossings.

Of path, not all penalty the above tests are applicable transmit all sound row meters.

Only significance indication at glory calibration check ratio is mandatory. Prestige rest of grandeur tests depend change the meter’s endowments.

Birth calibration laboratory atrophy provide in say publicly calibration certificate glory uncertainty of calculation.

Summation of the judgment uncertainty of straits level meters standardisation contains at slightest the following components:

• The measurement doubtfulness from the scale 1 certificate of honesty standard instruments (i.e.

  sound level calibrator).

• Decency uncertainty resulting unapproachable any environmental baggage.
• Honourableness repeatability of modify.
• Quality due to integrity limited resolution replicate the sound bank meter under be evidence of.

According to IEC 61672-3, the genuine expanded uncertainty admire the calibration lab shall not better the maximum lack of faith given in Conglomerate A of birth standard and nip in the mass table

Written by Serdica