Dual Channel ModeSingle Channel ModeRoom AcousticsPresentation
Presentation
Experience and Approach

Due to our long-term activity in the electro-acoustical domain today we can meet the requirements for nearly any field measurement and analysis application imaginable. Even tough measurements are helpful in selecting the right approach in solving a problem, it’s experience that allows saving time, financial resources and by the end having a problem solved in an elegant and modern way.

Before we set out to make any acoustical measurement, it is always helpful to define objectives clearly. Usually we want to measure the acoustical impulse response in a venue for some reason, but what exactly is this venue? Is it a church? Is it the sound system of an ice ring? Is it a combination of a sound system and its acoustical environment? What do you want to know about the system? What equipment and measurements will be needed to make sure you get the information you need? When approaching our tasks, we focus on the request we receive and search for the most realistic and rational solution. By doing so there may will be venues where measurements may not be necessary and circumstances where it is difficult to reach targets without single or dual channel FFT analysis. Hereafter we represent the areas we feel qualified to intervene, our measurement capabilities and application examples in a short form.

Areas of interest

  • Room acoustics
  • Auditorium, Church and Classroom Acoustical Design
  • Recording Studios and public venues

 Measurement capabilities

  • Time and Frequency Domain Analysis
  • Fourier Transforms (DFT/FFT and IFT) - Single Channel and dual channel
  • RTA Measurements, Real-Time Spectrograph
  • Dual Channel Transfer Function Measurements
  • Impulse Response Measurement

Application Examples 

  • Impulse Response Measurement - An impulse response (IR) can be defined as the time domain (time vs amplitude) response of a system under test to an impulsive stimulus. The impulse response (IR) is the acoustical signature of a system. The IR contains a wealth of information about an acoustical system including arrival times and frequency content of direct sound and discrete reflections, reverberant decay characteristics, signal-to-noise ratio and clues to its ability to reproduce intelligible human speech, even its overall frequency response. The impulse response of a system and its frequency-domain transfer function turn out to be each other’s forward and inverse Fourier transforms. This application requires a one channel mode setup and allows to define the type of sound system to be considered for a specific venue. If the system is for example highly reverberant a high Q system (highly directive) is the best choice.
  • Dual Channel Transfer Function Measurements - The transfer function is a dual-channel measurement technique that determines a system’s frequency response by comparing its input signal (the reference signal) to its output (measurement signal). The result of this measurement is a complex signal that represents the difference between the measurement and reference signals in both magnitude and phase. The measurement results show us the aggregate processing behavior of the system under test as a function of frequency or time. The transfer function allows you to examine the frequency response of components of a sound system, both electrical (EQ’s, mixers, processors) and electro-acoustical (loudspeakers, their drive electronics and their acoustical environment). This type of measurement is very useful in a wide range of applications, including loudspeaker design, equipment evaluation, equalization and sound system optimization.

About Fast Fourier Transformation (FFT)

Fast Fourier Transformation (FFT) is an integral function that has several applications in engineering and physics; in acoustics it is applied to a system’s impulse response and allows to convert signals from time domain to frequency domain. Being the FFT function reversible (IFFT) it is possible to convert frequency data back to time data. There are several measurement systems (hardware or software) that implement FFT algorithms. Increased computational power offers the advantage to analyze multiple channel simultaneously with higher sampling rates. A transfer function, for instance, is obtained by applying an FFT to a segment of the system's impulse response deriving Frequency Response, Phase Response, Group Delay and other relevant data.

 

 

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