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Audio analyzers: What they are and what they do

When you need to determine the output capability and quality of an audio device, you can use an audio analyzer as your go-to tool.

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Image: Blue Microphones

An audio analyzer is an instrument used to measure the quality of sound made by various other musical or electro-musical instruments. Note that when talking about audio quality, various metrics come into play such as noise, level, harmonics, gain, and frequency response.

When using an audio analyzer, a baseline from the instrument that is being tested will be used to compare any sound that is derived from the instrument. This baseline sound is called the characteristic while the output sound (also called signal) is known as the response.

The signal may be produced by the audio analyzer or can be produced externally by a different source such as a recording.

Since audio analyzers are used to test other devices, it is essential that they produce a higher quality sound compared to the other devices being tested. This means that the best quality audio analyzers should be able to provide high-quality sound with less distortion, less noise, and less interference. Moreover, to be deemed viable and usable, audio analyzers should be able to consistently produce high-quality output.

Audio analyzers are used in the development of other products. For instance, a design engineer will use an audio analyzer to test the sound quality of a product such as a microphone, a megaphone, a mobile phone, or a headset.

How Audio Analyzers Work

Image: Blue Microphones

At the heart of every audio analyzer is a generator that is responsible for creating a stimulus for the device being tested.

These generators also have input stages and can take both analog and digital signals from the device being tested. The audio analyzer will then convert these signals into digital or analog formats for testing.

Other features include:

  • An output filter for the response
  • An output that allows the user to interpret the information.

Issues with Electroacoustic Devices

The use of an audio analyzer to test electroacoustic devices present certain challenges. Because such devices receive and transmit audio signals through the air, there is a need for additional equipment including: a loudspeaker, a power amplifier for the loudspeaker, a microphone, and a microphone pre-amplifier.

To allow the tester to subtract such contributions from the extra devices and remain only with the results of the device under test, the signal contributions of these devices need to be characterized beforehand.

When searching for an audio analyzer, it is recommended that you choose a more modern model as this will have measurement sequences that simplify the process just described.

A Closer Look at the Audio Generator

When shopping for an audio analyzer, a highly crucial component is the audio generator. The key factors that you will need to consider include the capacity to generate different types of waveforms such as sine, sweep and multitone as well as:

  • Large amplitude range
  • Very low distortion and amplitude tests
  • Accurate source impedance
  • Good frequency range
  • High amplitude accuracy
  • AC/DC coupling
  • Different output options – balanced and unbalanced

Understanding the Signal Analyzer

The earlier versions of audio analyzers were designed with separate audio generators and single analyzers. However, more modern models are integrated and feature signal analyzers. This is the part that handles the actual signal analysis. You can find out more about the most reliable audio analyzers for audio precision on Linkedin, such as when you are testing loudspeakers.

A high-quality audio analyzer needs to have a highly accurate engine that is capable of precision measurements. To make sure, you can check for features such as: 

  • A frequency counter
  • A notch filter and bandpass
  • An AC/DC voltmeter
  • Weight filters for high pass and for low pass.

Different Parameters Measured By Audio Analyzers

Wholesalers, retailers, and buyers in the know are aware that you can use an audio analyzer to test the quality of devices such as DVD players, speakers, audio power amplifiers, and home theater systems, to mention a few.

  • Frequency response – This is the output of a device being tested. This output is expressed as a function of the frequency. When dealing with audio equipment, the measure of frequency response aims at reproducing the input signal while removing all minimal distortions. 
  • Crosstalk – This is a signal appearing in an audio channel. This is an unwanted signal that sounds as it does in the device being tested. Think of it as the ratio of the unwanted signal in one audio channel compared to another audio channel. The factors that can cause crosstalk include inductive or capacitive coupling that runs from one circuit to another. It is easier to achieve good crosstalk in modern digital stereo systems compared to the bygone days of FM radios and vinyl recordings.
  • Signal-to-Noise Ratio – This refers to the ratio of the ideal signal to the unwanted noise produced by the device being tested. In other words, it is the ratio of signal power compared to noise power.
  • Intermodulation distortion (IMD) – When two or more signals mix in a nonlinear fashion, this mix causes intermodulation distortion. Since all forms of audio equipment will come with a certain level of non-linearity, they will therefore have IMDs. Some, however, will have such low levels that the human ear cannot pick up these IMDs.
  • Level – This is the size or magnitude of the signal. It may be expressed in Watts, Volts, dBU or dBV (decibels as referenced to voltage).
  • Gain – This refers to the ratio of output signal compared to the input signal of the device that is being tested.
  • Phase – Expressed in degrees, this is the time relationship between two signals of similar frequency.
  • Total Harmonic Distortion Plus Frequency – The THD is expressed as multiples of stimulus frequency. Noise, on the other hand, is the energy that is not related to the input signal.
  • Time Domain Display – This is a display that shows instant amplitude changes versus time.

Takeaways

When you need to determine the output capability and quality of an audio device, you can use an audio analyzer as your go-to tool. This instrument allows you to measure various metrics related to audio quality such as gain, phase, signal-to-noise ratio, intermodulation distortion, and frequency response. When choosing an audio analyzer, make sure and choose only the best quality equipment that has the lowest levels of distortion, noise, and interference.

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