九游棋牌

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Micro-speakers and Headphone Drivers

Examples

 

 

Low-frequency drive unit
  • Micro-speaker
  • Transducers for headphones
  • Analogue and digital telephones
  • Handsets and headsets

Application

 

 

  • Telecommunication
  • Consumer and convenience applications including wireless and mobile communication devices


Particularities

Microspeakers and transducers for headphones are transducers reproducing not only speech signals but more and more full band audio signals. Some of the transducers are also used below the resonance frequency ranging from 100 Hz – 2 kHz. Most high frequency drive units use moving coil technology dispensing with a separate spider and surround. The moving coil assembly is prone to rocking modes, to irregular vibration modes of the wire and the rim zone and to hard limiting at maximal excursion causing Rub & Buzz and other impulsive distortion. 
The electrical, mechanical and thermal behavior of the drive unit at fundamental resonance frequencies can be described by the equivalent network comprising lumped elements with linear and nonlinear parameters. Distributed parameters are required to describe the vibration and radiation behavior at higher frequencies where the radiator (diaphragm) does not vibrate as a rigid body and bending and longitudinal waves propagate in circumferential and radial direction. 


The linear parameters comprise the Thiele-Small parameters and visco-elastic parameters (creep factor). The inductance and the losses due to eddy currents are negligible. The dominant nonlinearities are the force factor Bl(x), stiffness Kms(x) or compliance Cms(x) and the nonlinear damping Rms(v) versus velocity v. The nonlinear variations of the inductance L(i) and L(x) versus input current i and x are usually negligible. Direct mechanical measurements of the mechanical vibration by optical sensors (e.g. laser scanning techniques) are required to measure the mechanical parameters (T/S) including the effective radiation area Sd reliably. 
九游棋牌Perturbation techniques are difficult to apply because an added mass cannot be attached to the diaphragm, and a precise value of Sd is not available for the enclosure technique. Thermal parameters describe the heating of the coil, the heat transfer to the pole tips, the magnet and the ambience.


Critical Issues

  • Rocking modes and other irregular vibration modes
  • Rub & Buzz, air leakage noise and other impulsive distortion
  • Heating of the coil and thermal power handling
  • Asymmetry of the stiffness nonlinearity Kms(x) of mechanical suspension
  • Nonlinear mechanical resistance Rms(v) dominates total damping
  • Asymmetry of the B field and voice coil rest position


Standards

American National Standards Institute
ANSI S3.7 Method for Coupler Calibration of Earphones
ANSI S3.22 Specification of Hearing Aid Characteristics 
ANSI S3.25 Standard for an Occluded Ear Simulator

International Electrotechnical Commission
IEC 60268-5 Sound System Equipment, Part 5: Loudspeakers
IEC 62458 Sound System Equipment – Electroacoustic Transducers - Measurement of Large Signal Parameters

Institute of Electrical and Electronics Engineers
IEEE 269 Standard Methods for Measuring Transmission Performance of Analog and Digital Telephone Sets, Handsets, and Headsets
九游棋牌IEEE 1329 Standard Method for Measuring Transmission Performance of Handsfree Telephone Sets

International Telecommunication Union
九游棋牌ITU-R Recommendation BS. 775-2 Multi-channel Stereophonic Sound System with and without Accompanying Picture


most relevant measurements 

modules of r&d system

九游棋牌modules of qc system

Linear lumped parameters
(resonance frequency, Q-factors, Thiele/Small, creep, inductance)

Linear Parameter Measurement (LPM)
Multipoint Measurement Tool (MMT)

Impedance Task (IMP)
T/S Parameter Laser Fitting (TSX)

九游棋牌effective radiation area sd

Scanning Vibrometer System (SCN)

 

Loudspeaker nonlinearities
九游棋牌(Bl(x), Kms(x), L(x) , Rms(v))

Large Signal Identification (LSI Tweeter)

 

Single-valued nonlinear parameters
(Xmax , XBl , XC , Voice coil offset Xoffset , Suspension asymmetry AKms)

Large Signal Identification (LSI Tweeter)

Motor + Suspension Check (MSC)

Thermal parameters (resistances, time constant, capacities, air convection
cooling)

Large Signal Identification (LSI Tweeter)
Power Testing (PWT)

 

Irregular loudspeaker defects
九游棋牌(Rub & Buzz, loose particles, wire beat, bottoming, air leakage noise)

Transfer Function Measurement (TRF PRO)

Air Leak Detection (ALD)
Equalization & Alignment (EQA)
Hi-2 Weighted Harmonic Distortion (Hi-2)
Meta Hearing Technology (MHT)
Sound Pressure Task (SPL)
Sound Pressure and Impedance Task (SPL-IMP)
Spectrogram 3D Limits (3DL)

Air leakage noise localization
(position of modulated noise source)

 

Air Leak Stethoscope (ALS)

Amplitude response
(sensitivity, mean SPL, polarity)

3D-Distortion Measurement (DIS)
Linear Simulation (LSIM)
Multi-Tone Measurement (MTON)
Simulation (SIM)
Simulation-Auralization (SIM-AUR)
Transfer Function Measurement (TRF)

Equalization & Alignment (EQA)
Spectrum Analysis (SAN)
Sound Pressure Task (SPL) 
Sound Pressure and Impedance Task (SPL-IMP)
Multi-Tone Distortion Task (MTD)

Nonlinear harmonic distortion
九游棋牌(THD, components)

3D-Distortion Measurement (DIS)
Transfer Function Measurement (TRF)

Equalization & Alignment (EQA)
Hi-2 Weighted Harmonic Distortion (Hi-2) 
Spectrum Analysis (SAN)
Sound Pressure Task (SPL) 
Sound Pressure and Impedance Task (SPL-IMP)

九游棋牌intermodulation distortion (imd)

3D-Distortion Measurement (DIS)

 

Amplitude intermodulation distortion (AMD)
九游棋牌(modulation of the fundamental)

3D-Distortion Measurement (DIS Pro)

ear

Thermal and nonlinear compression
(fundamental, harmonics, dc displacement)

3D-Distortion Measurement (DIS)

Multi-Tone Measurement (MTON)

Multi-Tone Distortion Task (MTD)

Peak displacement
DC displacement

3D-Distortion Measurement (DIS)
Live Audio Analyzer (LAA)
Large Signal Identification (LSI)
Large Signal Identification (LSI3)
Multi-Tone Measurement (MTON)
Transfer Function Measurement (TRF)

Dynamic Excursion Check and Control (DCX)
Motor + Suspension Check (MSC)
T/S Parameter Laser Fitting (TSX)
Multi-Tone Distortion Task (MTD)

九游棋牌multi-tone distortion

Linear Parameter Measurement (LPM)
Multi-Tone Measurement (MTON)

Multi-Tone Distortion Task (MTD)

九游棋牌phase response

Transfer Function Measurement (TRF)

Equalization & Alignment (EQA) 
Spectrum Analysis (SAN)
Sound Pressure Task (SPL)
Sound Pressure and Impedance Task (SPL-IMP)

九游棋牌minimal-phase, excess-phase, group delay

Transfer Function Measurement (TRF)

Equalization & Alignment (EQA) 
Spectrum Analysis (SAN) 
Sound Pressure Task (SPL) 
Sound Pressure and Impedance Task (SPL-IMP)

time-frequency analysis (wigner, cumulative decay spectrum, sonagraph, wavelet, …)

Time Frequency Analysis (TFA)
Transfer Function Measurement (TRF)

Spectrogram 3D Limits (3DL)

Accelerated life test, power test
九游棋牌(durability, parameter variation)

Live Audio Analyzer (LAA)
Large Signal Identification (LSI)
Power Testing (PWT)

 

九游棋牌coil temperature

3D-Distortion Measurement (DIS)
Live Audio Analyzer (LAA)
Large Signal Identification (LSI)
Power Testing (PWT)

 

Distortion generated by dominant nonlinearities
九游棋牌Bl(x), Cms(x), Le(x), Rms(v) in reproduced audio signal

Large Signal Identification (LSI)
Power Testing (PWT)
Simulation-Auralization (SIM-AUR)

 

accumulated acceleration level (aal)

Scanning Vibrometer System (SCN)

 

Decomposition into radial and circumferential mode
(indicating rocking mode)

Scanning Vibrometer System(SCN)

 

九游棋牌polar radiation response analysis (far field spl response at spatial resolution), directivity index, sound power

Near Field Scanner (NFS)
Scanning Vibrometer System (SCN)

 

modal analysis (natural frequencies, shape of natural modes, modal loss factor)

Higher Mode Analysis (HMA)
Rocking Mode Analysis (RMA)
Scanning Vibrometer System (SCN)

 

auralization

Simulation-Auralization (SIM-AUR)

Sound Pressure Task (SPL)
Sound Pressure and Impedance Task (SPL-IMP)

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