The rectifier converts the electrical signal from alternating current (AC) to direct current (DC) to cause the display meter to register the sound pressure level directly in decibels. By surveying each component with a sound intensity meter the sound power for each component can be determined separately. It has a lower cutoff frequency of 3 Hz and an upper cutoff frequency of 20 kHz. The C scale treats all frequencies within the operating range approximately equally.
You need a calibrated Class 2 Integrating Sound Level Meter and you also need a Sound Level Calibrator. 162 0 obj << /Linearized 1 /O 174 /H [ 2061 900 ] /L 1370181 /E 342075 /N 18 /T 1366822 >> endobj xref 162 40 0000000016 00000 n
A sound level meter can be used for measuring sound or noise* for Community Noise Analysis, Building Acoustics, Industrial Noise Control, Machinery Noise Analysis, and further applications. Weighting curves for sound level measurements.
The responsiveness of human hearing changes with age. Computers may be used for noise analysis when connected to dedicated hardware devices.
These frequency weighting schemes were designated by letters of the alphabet, A, B, C, and so forth. Unit 14/22 Hudson Ave, Castle Hill, N.S.W 2154 . 0000001470 00000 n In practice, a basic sound level meter will incorporate weighting networks with either in-built octave filters or provision for connecting an external filter set (Figure 42.6). Sound level meters are graded according to British and international standards, and the most common type used for accurate measurement purposes it known as the Precision Grade or Type 1 meter.
1/1 gives us a single measurement value for each octave (12 semi-tones), 1/3 provides a single value for groups of 4 semi-tones, 1/6 represents 1 semi-tones, while 1/12 is a separate level measurement for every key on the piano. We use cookies to help provide and enhance our service and tailor content and ads. A significant amount of acoustic data is still measured and reported in octave and 1/3-octave filtered measurements, but these measurements are crude compared to those from a spectrum analyser that can perform narrowband analysis. During the testing of another package, the sound power levels from the ventilation fan casing and the fan motor were measured separately.
1.2. The A, B, and C curves can be regarded as very rough approximations to the contours of equal loudness [10] at 40, 70, and 100 phons respectively in order to compensate for the reduced sensitivity of the ear to very low and very high frequencies. Precision Grade for laboratory and field use, Environmental, building acoustics, road vehicle, Noise at work, basic environmental, motor sport. In either case, the environment is totally unsuitable for reliable acoustic tests to be carried out using sound level meters alone. 0000002061 00000 n 0000095702 00000 n The relative weightings in each third-octave band for the A and C filters are set forth in Table 3.1. The needle in- dicator shows the actual sound level as a displacement from the center point. %�쏢
If the A scale has been used the result must be given in dBA. Different kinds of sound level meters. 0000001971 00000 n
Many integrating sound-level meters allow the interruption of the integrating process or the summation of energy in separated periods. 0000087831 00000 n The A scale discriminates against frequencies below 800 Hz.
Leo L. Beranek, Tim J. Mellow, in Acoustics: Sound Fields and Transducers, 2012, The sound level at a point in a sound field is the reading in decibels (dB) of a sound-level meter constructed and operated in accordance with the latest edition of “American National Standard Specification for Sound Level Meters.” [9]. INTRODUCTION This chapter describes the noise measuring instruments most widely used in the practice of occupational hygiene.
0000024481 00000 n ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. URL: https://www.sciencedirect.com/science/article/pii/B9780750683081000322, URL: https://www.sciencedirect.com/science/article/pii/B978075067291750042X, URL: https://www.sciencedirect.com/science/article/pii/B9780750673280500446, URL: https://www.sciencedirect.com/science/article/pii/B9780128126325000136, URL: https://www.sciencedirect.com/science/article/pii/B9780128038062000169, URL: https://www.sciencedirect.com/science/article/pii/B9780123914217000014, URL: https://www.sciencedirect.com/science/article/pii/B9780123982582000039, URL: https://www.sciencedirect.com/science/article/pii/B9780124104617000067, URL: https://www.sciencedirect.com/science/article/pii/B9781845694975500042, Instrumentation Reference Book (Fourth Edition), Reference Data for Engineers (Ninth Edition).
0000001905 00000 n The simplest sound level meter consists of a microphone, an amplifier and a meter of some type.
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