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How To Test And Evaluate Audio Equipment

Acoustic Testing Equipment

One of the essential aspects of sound engineering and sound production is the maintenance of the sound quality and audio performance of all the equipment, instruments, and devices used by the production crew. Most people are familiar with some of this equipment and devices, such as speakers, loudspeakers, amplifiers, and mini speakers. In addition, it also includes things they use almost every day, such as earphones, microphones, headsets, and stereos.

Perhaps most people may not know that these electro-acoustic devices generally undergo a lot of testing and evaluation before allowing them to roll out in manufacturing plants. Sound engineers and their team of audio analysis professionals do a lot of tests to ensure these equipment, instruments, and devices meet the standards and requirements in every industry where they’re going to be used.

You can consult sound engineers to use Audio Precision test equipment for your instruments to have a more accurate gauge of their condition. Furthermore, here’s a brief article on how to test and evaluate audio equipment, including electro-acoustic instruments and devices.

How Audio Analyzers Test Audio Performance 

There are industry-prescribed audio analyzers used to test and evaluate audio equipment. These audio analyzers are meant to check the sound quality and measure the audio performance of electro-acoustic devices. In addition, these are also widely used to assess the condition and performance of various kinds of sound equipment.

Audio analyzers can be used in many different ways to check the sound quality and performance of stereos, speakers, loudspeakers, and microphones. In addition, these can be used to test small things such as mobile phones, headsets, earphones, and other top gadgets people use in their home offices, such as unidirectional microphones and noise-cancellation headsets. Moreover, they have also been used to assess and evaluate audio software applications, as well as voicemail apps.

Audio analyzers test the sound coming from various electro-acoustic devices by measuring the strength and quality of the signals they produce when they make sounds. There are times when these audio equipment analyzers may have to use sound cards or special software applications when they cannot execute the tests without these. However, in some cases, you may not be able to use audio analyzers to measure sound quality and device performances unless you use sound cards or software apps.

In general, here’s how an audio analyzer typically works:

  • The audio analyzer sends a test signal to the device they’re testing. Audio technicians often refer to this as the device under testing or DUT.
  • The DUT then responds by emitting its own signal. It is the DUT’s response to the one sent by the audio equipment analyzer.
  • The operator of the audio equipment analyzer would then compare the original test signal of the audio analyzer with the output signal received from the DUT.
  • It isn’t manually done, though. There’s a special software application installed in the audio equipment analyzer. It is used to analyze the audio quality and performance of the DUT.
  • The software application looks at the test signal and the output signal. It will then search for distinctions and differences between the original test signal and the output signal.
  • The audio analyzer’s special software uses several standardized parameters and operational indicators to evaluate the divergence, if any, between the original test signal and the DUT’s output signal.

Listed below are some of the standardized parameters and evaluation metrics used by audio equipment analyzers to test and evaluate different electro-acoustic devices and electronic audio instruments

  • Gain
  • Signal-to-noise (SNR) ratio
  • Total harmonic distortion plus noise (THD+N)
  • Crosstalk
  • Phase

How Audio Analyzers Measure Audio Performance 

Acoustic Testing Equipment

Audio equipment analyzers can be used in several different ways to test and measure the sound quality and performance of various electro-acoustic devices and electronic audio instruments. Here are just a few of those:

1. Rub & Buzz Detection 

One of the standard tests used to measure the sound quality and performance of electro-acoustic devices is called Rub & Buzz Detection. This test is applied to look for defects in the audio equipment that has something to do with the occurrence of a high peak ratio accompanied by a high crest factor. The Rub & Buzz Detection test uses a chirping stimulus to identify defects and evaluate equipment performance.

The Rub & Buz Detection test can detect if some of the DUT’s suspension elements aren’t fixed to the frame stably and rigidly using adhesive components. The human ear can be highly sensitive to these buzz noises, although they’re difficult to notice and identify using standard detection techniques such as FFT.

The Fast Fourier Transform, or FFT for short, is a vital mathematical method in acoustics and audio measurement. This method works by converting a signal into components that contain frequency information.

2. Air Leak Detection

Some audio equipment analyzers can also be used to identify if the DUT has any existing air leaks and defects. These tools are typically modulated noise measurement devices, which may work by using the air leak defects to come with some sort of weighted white noise. Here’s how it works:

  • A low-frequency stimulus is produced/emitted by the audio equipment analyzer to modulate the weighted white noise.
  • The model created from the weighted white noise has been used to check enclosures in electro-acoustic devices to look for leaks.
  • Some typical causes of air leaks could be traced back to when the device, equipment, or instrument was made. They can also be caused by poor sealing of enclosures, as well as open jacks.
  • A concrete example of when air leaks have to be detected and identified is because they can have a negative impact on the equipment performance and sound quality of loudspeakers.

Air leaks can significantly affect the way that loudspeakers can function and perform. For one, air leaks can produce unwanted noise. Detecting unwanted noise interferences can sometimes be hard to spot, even if the audio equipment analyzer operator employs several standard measurements and testing parameters.

In some instances, air leaks could get buried in the noise floor. When this happens, it may be difficult to distinguish the interference coming off from the air leaks from the rest of the noise.

3. Thiele-Small Measurement  

The Thiele-Small test is a measurement of the complex acoustic impedance of a loudspeaker. This measurement test provides calculated electromechanical parameters which can be used to evaluate critical indicators in a loudspeaker. These parameters are then used to find out if there are occurrences of low-frequency performance in loudspeaker drivers.

Furthermore, the results that the Thiele-Small tests yield can be used to describe the interaction between the enclosure and the loudspeakers. Generally, these are crucial to the subsequent tests that are, in turn, done when the loudspeakers are being designed up until the production stage.

In some cases, the results produced by the Thiele-Small measurement tests can have a measured deviation from what we’re supposed to expect from the Thiele-Small parameters. These measured deviations can be highly useful in finding out and detecting if there are any quality defects in the device parts on the DUT.

Some of the methods used in the Thiele-Small measurements tests include the Known Volume, Known Mass, and Added Mass methods. By applying the Known Mass method, the measurement tests will attempt to come up with accurate Thiel-Small characterizations using a single pass. On the other hand, two-pass measurements are applied in the Known Volumes and Added Mass measurement tests. These two main tests, based on the number of passes, are capable of delivering accurate parameters.

The audio equipment analyzer generally computes the standard parameters of acoustic response when it executes the test. The response of the DUT to the original test signal or test stimulus is measured using the standard parameters.

Here are a few of the various measurements executed by the audio equipment analyzer:

  • Level of the sound or noise
  • Phase
  • Frequency response
  • Group delay
  • Distortion

The acoustic responses of the DUT are typically returned as graph measurements and reported through the audio test drives. The results would then be displayed on the screen of the audio equipment analyzer. Another way of using the measurement tests would be to export the data in table formats.

4. Advanced Equipment Sophistications 

Some of the most advanced equipment used in audio equipment analysis may have very sophisticated features and functions. Creators of this advanced equipment typically integrate instrument-grade amplifiers with microphone power supplies. Sound equipment designers, sound engineers, and production test engineers may prefer testing equipment with advanced features in performing their audio equipment measurement tests.

Sound engineers and other audio professionals are highly-skilled in what they do. They’re often very exacting and meticulous in making choices about the audio testing equipment and measurement devices that they’re going to use.

The Bottomline 

Audio equipment analyzers are essential measurement tools used to ensure that all electro-acoustic instruments and electronic audio devices are safe. Audio equipment analyzers can also be used to guarantee that these electro-acoustic devices would meet industry standards and requirements before they’re allowed to leave their manufacturing hubs. To maintain standards compliance, audio engineers and sound technicians perform different tests on electro-acoustic devices.

Author: Therese Smith

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