Control of Vibration at Work Regulations

Action and Limit Values for Hand Arm and Whole Body Vibration.

The Noise at Work Directive 2003/10/EC defines the following limit and action values:

LCpeak is the maximum value of the C-weighted, instantaneous noise pressure.

see also Daily Personal Noise Exposure LEP,d

If the Leq is measured over 8 hours then Leq and LEP,d and LEX,8h would all be the same.

The European Directive recommends LEX,8h is adopted from 2006 onward.

see also Leq - Equivalent Continuous Sound Level

The action of frictional or dissipative forces on a dynamic system causing the system to lose energy and reduce the amplitude of movement.

Removal of echoes and reverberation by the use of sound absorbing material.

see also Reverberation Time.

Day-evening-night Noise Indicator : Lden

Day-night Noise Indicator : Ldn

**dB : **decibel

♦ Note 1 : the kind of level is indicated by use of a compound term such as Sound Power Level or Sound Pressure Level.

♦ Note 2 : the value of the reference quantity remains unchanged, whether the chosen quantity is Peak, the RMS, or otherwise.

♦ Note 3 : the base of the logarithm is indicated by use of a unit of level associated with that base.

**dB SIL : **Sound Intensity Level

**dB SWL : **Sound Power Level

L in dB = 20 · lg (V/Vo)

see also : AC Coupling.

♦ Note 1 : The decibel is more often used than the bel as a unit of level.

♦ Note 2 : The decibel can be defined as a unit of level of a power-like quantity when the base of the logarithm is the tenth root of ten. Also, the decibel is the unit of level of a field quantity when the base of the logarithm is the 20th root of ten.

**decibel scale** a linear numbering scale used to define a
Logarithmic amplitude scale, thereby compressing a wide range of amplitude values to a small set of numbers.

Vibration Levels | Sound Levels | |||

Acceleration : La | Velocity : Lv | Particle Velocity : Lv | Pressure : Lp | |

dB | m/s^{2} | m/s | m/s | Pa : N/m^{2} |

0 dB | 1 x 10^{-5} | 1 x 10^{-9} | 5 x 10^{-8} | 2 x 10^{-5} |

20 dB | 1 x 10^{-4} | 1 x 10^{-8} | 5 x 10^{-7} | 2 x 10^{-4} |

40 dB | 1 x 10^{-3} | 1 x 10^{-7} | 5 x 10^{-6} | 2 x 10^{-3} |

60 dB | 1 x 10^{-2} | 1 x 10^{-6} | 5 x 10^{-5} | 2 x 10^{-2} |

80 dB | 0.1 | 1 x 10^{-5} | 5 x 10^{-4} | 0.2 |

100 dB | 1.0 | 1 x 10^{-4} | 5 x 10^{-3} | 2.0 |

Table Notes :

0 dB is the reference level for each parameter.

The parameters above use the 20 Lg formulae for example 20 Log10 (P/Po) dB for Sound Pressure Levels.

Sound | Power Level : LW | Intensity Level : LI | Energy Density Level : LE |

dB | Watts | Watts/m^{2} | Joules/m^{3} |

0 dB | 1 x 10^{-12} | 1 x 10^{-12} | 1 x 10^{-12} |

20 dB | 1 x 10^{-10} | 1 x 10^{-10} | 1 x 10^{-10} |

40 dB | 1 x 10^{-8} | 1 x 10^{-8} | 1 x 10^{-8} |

see also Reference Quantities Table

Although in common use, the degree is not part of the International System of Units (SI) the derived unit is the Radian.

see also Angles

SI units: kilogram per cubic metre, kg/m^{3}

At sea level and at 20 °C, air has a density of approximately 1.2 kg/m

At sea level and at 0 °C, air has a density of approximately 1.3 kg/m

Stationary Signals.

Transients may also be deterministic.

Diffraction

Diffraction Factor

Place the source on the ground next to a wall so the radiation is concentrated into a 1/4 of the sphere, then Q=4.

If the source is placed on the floor in a corner, the sound energy is further concentrated into 1/8th of a sphere so Q = 8.

see also Tonal Assessment.

Displacement ξ = v/ω = a/ω^{2}, where v =
Velocity, a =
Acceleration and ω = 2·π·f = angular frequency.

Velocity v = a/ω

Displacement s = v/ω

So it follows that 10 m/s^{2} = 0.01 m/s = 10 μm at 159 Hz

This works for all frequencies, we just chose 159 Hz to keep the numbers simple. We also have a Vibration Nomogram for downloading.

see also :
Angular Displacement

Particle Acceleration

Particle Displacement used in acoustic wave theory

Particle Velocity

Standard Reference Levels table.

**Distance** change in position of an object in metres -

see also Displacement above.

♦ Note : Distortion may result from:

a) non-linear relation between input and output;

b) non-uniform transmission at different frequencies;

c) phase shift not proportional to frequency.

♦ Note : Divergence Loss exists, for example, for spherical waves emitted by a point source.

**Dn : **Normalized Level Difference

**DnT : **Standardized Level Difference

**DnT,w : **Weighted Standardized Level Difference

**DnT,w + Ctr : **Weighted Standardized Level Difference with Spectrum Adaption Term Ctr

**DOD** Department of Defence : USA.

**Dose related subjects : **

DOHR

Dose - Noise

Dose %

Dose Badge

Dose per Hour

Dose - Vibration

Dosimeter

**DSP : **Digital Signal Processing

**Dual Input Room Acoustics Calculator** DIRAC

**Dw : **Weighted Level Difference

1 dyne = 1 g·cm/s^{2} = 10^{-5} kg·m/s^{2} = 10 μN