IEC 61094-1:2000 pdf download

IEC 61094-1:2000 pdf download.Measurement microphones -Part 1:Specifications for laboratory standard microphones.
3.2
laboratory standard microphone
condenser microphone capable of being calibrated to a very high accuracy by a primary method such as the closed coupler reciprocity method, and meeting certain severe requirements on mechanical dimensions and electroacoustical characteristics, especially with respect to stability in time and dependence on environmental conditions
3.3
open-circuit voltage
alternating voltage appearing at the electrical output terminals of a microphone as measured by the insert voltage technique when the microphone is attached to the ground shield configuration specified in 7.2 but is otherwise unloaded
Unit: volt. V
NOTE Oeing to ti, capacitive nature t th. niecrophorie. the voltaQe at the electrical tqiminals depends cm the electrical load presented by the mechanical and e4ectric altachmenl of the microphone to a preamplifier, For tileS reason. preamplihers used for measurinp the open-circuit oltape of a microphone ilouId full dl the requirements of 7.2.
3.4
pressure sensitivity of a microphone
for a sinusoidal signal of given frequency and for given environmental conditions, the quotient of the opon.clrcuit voltage of the microphone by the sound pressure acting over the exposed surface of the diaphragm (I.e. at the acoustical terminals of the microphone), the sound pressure being uniformly applied over the surface of the diaphragm. This quotient Is a complex quantity, but when phase information is of no Interest the pressure sensitivity may denote Its modulus only
Unit: volt per pascal. V/Pa
3.5
pressure sensitivity level of a microphone
logarithm of the ratio of the modulus of the pressure sensitivity I to a reference sensitivity. The pressure sensitivity level in decibels is 20 Ig (l&fI PA.), where the reference sensitivity P1. Is 1 V/Pa
Unit: decibel, dB
3.6
tree-field sensitivity of a microphone
for a sinusoidal plane progressive sound wave of given frequency, for a specified direction of Incidence, and for given environmental conditions, the quotient of the open.circult voltage of the microphone by the sound pressure that would exist at the position of the acoustic centre of the microphone In the absence of the microphone. This quotient Is a complex quantity, but when phase information is of no interest, the freelield sensitivity may denote its moduius Only
Unit: volt per pascal. V/Pa
NOTE 1 At frequencies sufticienily low for the disturbance of the sound field by the microphone to be ne9legibie. the tree-field senSitivity approaches the pressure sensitivity see 6.9 for practical limilations).
NOTE 2 The position of the acoustic cantre is a function of rrequericy.
3.7
free-field sensitivity level of a microphone
logarithm of the ratio of the modulus of the free-field sensilivlty MI 10 a reference sensitivity. The free-field sensitivity level in decibels is 20 Ig (IMI I PA,), where the reference sensitivity PA. is 1 V/Pa
Unit: decibel. dB
3.8
diffuse-field sensitivity of a microphone
for a sinusoidal signal of given frequency in a diffuse sound field and for given environmental conditions, the quotient of the open•circuit voltage of the microphone by the sound pressure that would exist at the position of the acoustic centre of the microphone In the absence of the microphone
Unit: volt per pascal. V1Pa
NOTE I Al frequenciex sufficiently low for the disturbance of the Sound field by the microphone to be n.ligible.
the (SHuts-field sensitivity approaches the piessure sensitivity (see 6.9 los psaclical limilalional.
NOTE 2 The position of the acoustic centre is a (unctiOn 04 frequency.
3.9
diffuse-field sensitivity level of a microphone
logarithm of the ratio of the modulus of the diffuse-field sensitivity to a reference sensitivity. The diffuse-field sensitivity level in decibels is 20 Ig (IAI P4), where the reference sensitivity Mr is 1 V/Pa
Unit: decibel, dB
3.10
electrical impedance of a microphone
for a sinusoidal signal of given frequency, the complex quotient of the voltage applied across the electrical terminals of the microphone by the resulting current through those terminals. The microphone shall be connected to the ground-shield configuration specified in 7.2
Unit: ohm, 1
NOTE This impedance Is a function of the acoustical load on the diaplna9m
3.11
acoustic impedance of a microphone
lot a sinusoidal signal of given trequency, the complex quotient of the sound pressure by the volume velocity at the diaphragm, the Sound pressure being uniformly distributed over the surface of the diaphragm and the electrical terminals being loaded with an infinite Impedance.