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Simulation-Auralization (SIM-AUR)

Features and Benefits

  • Simulate long term thermal behavior
  • Auralization and analysis of arbitrary nonlinear effects
  • Calculates history of electrical, mechanical, acoustical and thermal state variables over time
  • Assess long term performance of the transducer in target applications
  • Exploit the main source of nonlinear distortion in the output signal
  • Evaluate the audible performance of the speaker
  • Simulate transducer behavior using arbitrary stimuli
  • Assess long-term performance of the transducer in target applications
  • Save time and costs in prototyping

The SIM-AUR module performs a numerical simulation of electro-dynamical drivers mounted in common enclosure systems. Unlike other modules, the applied stimulus can be any kind of signal (e.g. test signals, music, …) and arbitrary in length. It uses an extended lumped-parameter model to describe the transfer behavior in the full working range. The electrical, mechanical, acoustical and thermal state variables are calculated and available for extended analysis. Either real or fictitious driver and system data may be used as basis for the simulation. In addition, distinct nonlinear effects can be separated without affecting the simulated transducer system. This separation of the distortion in the acoustical output signal from the linear component is the basis for a new auralization technique where double blind A/B comparisons may be performed and the threshold of audibility is determined systematically. In addition, the separated signals are available for further analysis.

Thermal Operation

Fast simulation of voice coil and magnet temperatures while reproducing 5 h of common music material.

This operation is used to calculate the long-term thermal response of the transducer. A time-lapse feature for fast calculation is available. Using the time-lapse technique, the long test state variables, such as the magnet and pole-tips temperature, are approximately determined and can be used for further operations. The “Thermal”-operation must be the first operation of the SIM-AUR module. Every further operation depends on the transducer model and stimulus defined in this operation.

Time Lapse Technique

To assess the long term performance of the transducer, time consuming measurements or simulations must be performed. The longest time constants occur in the thermal system, which are a result of the slow heating of the magnet structure. The voice coil temperature of the transducer depends directly on the dissipated power. Since the thermal variation is relatively slow compared to the electro-mechanical transducer, a significant increase in simulation speed can be achieved by predicting the dissipated power and effective state variables.

The most important objectives are:

  • Fast thermal estimation of the long-term transducer performance
  • Exploit critical working conditions due strong thermal heating


The linear, nonlinear and thermal parameters identified by the LSI module are exported to the Simulation-Auralization (SIM-AUR) module. Identified parameters may be modified at will. An arbitrary test signal, provided as wave-file, is used as input file and can be virtually amplified (no clipping simulation). With the help of the time lapse technique, interesting sections of the input signal providing high amplitudes and heating can be identified fast.

To investigate the influence of the nonlinear distortion, the SIM-AUR provides a simple scaling window, where you can vary the ratio between linear signal and nonlinear distortion (from motor, suspension nonlinearities, or enclosure). The listener may listen to the output signal by using high-quality headphones or loudspeaker monitor systems. The signals can be exported, and used as basis for listening tests.


The new auralization technique is used to separate distinct nonlinear effects, such as effects due to nonlinear Bl, Le or Rms or other, without affecting the model state. This separation does not affect the speaker model itself. The separated effects can be used to determine the root cause of the nonlinear distortion. Also, the separated signal can be stored as a wave-file, giving the possibility to easily design auditory experiments to evaluate the impact on audible quality.

The most important objectives are:  

  • Separation of nonlinear effects without affecting the modelled speaker
  • Exploit the main source of nonlinear distortion in the output signal
  • Design auditory experiments to evaluate the audible impact of the nonlinear distortion
  • Evaluate the audible performance of the speaker at the target application
  • Find optimal performance-cost ratio
  • Assess distortion ratio in audio signals


Test Hardware

License Dongle (USB)




International Electrotechnical Commission
IEC 60268-13, IEC 62458

International Telecommunication Union
ITU-R Recommendation BS. 1116, ITU-R Recommendation BS. 1534-1


USA: 8,964,996B2

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