IEEE Std 656:2018 pdf download.IEEE Standard for the Measurement of Audible Noise from Overhead Transmission Lines.
IEEE Std 656 describes manual and automated procedures for measuring audible noise from overhead power transmission lines.
1.2 Purpose
The purpose of this standard is to establish uniform procedures for the measurement of audible noise from overhead transmission lines, using instrumentation that conforms to ANSI S1.4 or IEC 61672-1 [B2] standards.2 A uniform procedure is a prerequisite to valid evaluation and comparisons of the audible-noise performance of various overhead power transmission lines.
2. Normative references
The following referenced documents are indispensable for the application of this document (i.e., they must be understood and used, so each referenced document is cited in text and its relationship to this document is explained). For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments or corrigenda) applies.
ANSI S1.4,American National Standard Specification for Sound Level Meters.
ANSI S1.6, American National Standard Preferred Frequencies, Frequency Levels, and Band Numbers for Acoustical Measurements.
ANSI S1.1l, American National Standard Specifications for Octave, Half Octave, and Third Octave Band Filter Sets.
3. Definitions
For the purposes of this document, the following terms and definitions apply. The IEEE Standards Dictionary Online should be consulted for terms not defined in this clause.4 Additionally, IEEE Std 539 [B6] contains definitions related to corona and field effects aspects.
day-night sound level (Ldfl): The Ldn rating is the average A-weighted sound level, in decibels, integrated over a 24 h period. A 10 dBApenalty is applied to all sound occurring at night time, typically between 10 p.m. and 7a.m.
NOTE 1— L is intended to improve upon the L rating by adding a correction for nighttime noise intrusions because people are more sensitive to such intwsions.
NOTE 2—The L can be derived from daytime and nighttime L values as follows:
NOTE 3—The purpose of Ldr is to provide a single-number measure of time-varying noise for a specific time period (24 h). NOTE 4—If a different number of hours are considered daytime versus nighttime, the corresponding 15 h
and 9 h in the constants above must be adjusted accordingly.
energy-equivalent sound level (L): The average of the sound energy level (usually A-weighted) of a varying sound over a specified period of time.
NOTE 1—The simplest and most popular method for rating intermittent or fluctuating noise intrusions is to rely upon some measure of the average sound-level magnitude over time. The most common such average is the equivalent sound level, L, expressed in decibels.
NOTE 2—The term “equivalent” signifies that a steady sound having the same level as the L would have the same
sound energy as the fluctuating sound. The term "energy” is used because the sound amplitude is averaged on an rmspressure- squared basis, and the square of the pressure is proportional to energy. For example, two sounds, one of which contains 24 times as much energy as the other but lasts for 1 h instead of 24 h, would have the same energy-equivalent sound level.
NOTE 3—Mathematically, the equivalent sound level is defined as.IEEE Std 656 pdf download.