Answers.Body: <p>I don't think you will find many objective techniques to assess signal quality, because &quot;signal quality&quot; is a very subjective notion. What one person considers their signal of interest might be undesired noise for someone else, and one signal might be considered severely contaminated and deteriorated for a certain method/analysis but still useable for a different method/analysis.</p>
  <p>For better or worse, you need to have an understanding of your desired method/analysis and its requirements, and only then you can define what you need from your signals.</p>
  <p>Testing your hardware and signal chain in advance is very important. Having a consistent set of tests, and going through them in a controlled environment before heading out to the field should help identify issues such as faulty mics/sensors and cables, improper amplification gains or filter settings, etc, before they become a problem in the field. Once again, these tests will depend on the application, and there are no one-size-fits-all solution. Even simple things like clapping hands or finger snapping ~1m away from the mics, or placing a hydrophone inside a teacup filled with water (not tea!) and flicking the outside of the teacup with your fingers can already give you a rough idea of whether your signal chain is working well or faulty.</p>
  <p>Clipping is one of the few issues that are easy to identify visually: plot the recorded signal in the time domain and look for &quot;flatness&quot; in the top and/or bottom parts of the waveform. See the top two plots on this figure:</p>
  <p>[<img src="https://i.sstatic.net/tuQaE.jpg" alt=" from https://www.math.ucdavis.edu/~strohmer/research/audio/audio.html][2] " /></p>
  
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Body: <p>Some questions already touch on this regarding signal-to-noise ratio (SNR). However, this is only one component of audio quality. Many other issues (such as clipping, signal degradation/mic quality) can cause spurious results if not considered carefully. Yet, many papers simply make statements such as &quot;manually assessed for quality control&quot; or something of the like.</p>
  <p>It can thus be difficult for beginners to understand what criteria to pay attention to when selecting audio clips. Of course, different analytical techniques require different standards, further adding to the uncertainty.  Can someone point to some more objective standards (including published articles) for decision making guidelines on when to include/when to discard audio signals?</p>
  
Tags: <analysis>
Title: How to assess the quality of audio signals?
ThreadText: # How to assess the quality of audio signals?
  
  (Asked by: username_0 on 2022-07-15)
  
  Some questions already touch on this regarding signal-to-noise ratio (SNR). However, this is only one component of audio quality. Many other issues (such as clipping, signal degradation/mic quality) can cause spurious results if not considered carefully. Yet, many papers simply make statements such as "manually assessed for quality control" or something of the like.
  
  It can thus be difficult for beginners to understand what criteria to pay attention to when selecting audio clips. Of course, different analytical techniques require different standards, further adding to the uncertainty. Can someone point to some more objective standards (including published articles) for decision making guidelines on when to include/when to discard audio signals?
  
  **Tags:** analysis
  
  
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  ## 1 answers
  
  ### Answer by username_1 on 2022-07-15. Score: 7
  
  I don't think you will find many objective techniques to assess signal quality, because "signal quality" is a very subjective notion. What one person considers their signal of interest might be undesired noise for someone else, and one signal might be considered severely contaminated and deteriorated for a certain method/analysis but still useable for a different method/analysis.
  
  For better or worse, you need to have an understanding of your desired method/analysis and its requirements, and only then you can define what you need from your signals.
  
  Testing your hardware and signal chain in advance is very important. Having a consistent set of tests, and going through them in a controlled environment before heading out to the field should help identify issues such as faulty mics/sensors and cables, improper amplification gains or filter settings, etc, before they become a problem in the field. Once again, these tests will depend on the application, and there are no one-size-fits-all solution. Even simple things like clapping hands or finger snapping ~1m away from the mics, or placing a hydrophone inside a teacup filled with water (not tea!) and flicking the outside of the teacup with your fingers can already give you a rough idea of whether your signal chain is working well or faulty.
  
  Clipping is one of the few issues that are easy to identify visually: plot the recorded signal in the time domain and look for "flatness" in the top and/or bottom parts of the waveform. See the top two plots on this figure:
  
  [![ from https://www.math.ucdavis.edu/~strohmer/research/audio/audio.html][2] ](https://i.sstatic.net/tuQaE.jpg)
  
  
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