How to compare two audio files quality wise?

February 28, 2009 by
Filed under: Voice and Sound Quality Testing Software 

In order to compare two audio signals we introduce the analytical module, which compares separately combined pairs of fragments of active and inactive phase signal that allows getting more accurate estimation.

For each fragment we determine integral spectrum by using discrete cosine transformation (DCT). Spectrum integration is calculated according to the proprietary formula. In the spectrum calculation the interpenetration of windows comes to N/2 samples, and the Hamming or Blackmann-Harris window function is applied to every window. Levels of spectrum energy on bands are determined for all sets of bands. Groups of critical bands, determined by different authors resulting from different models of sound perception and speech production.

Band boundaries (initial and terminal indices) as well as band energy values we determine by a set of proprietary formulas. The initial quality estimation value is taken as 100%, which decreases proportionally to distinction of energies on bands. The most interesting fact is that we can scale down our percentage of signals similarity to the well-known Mean Opinion Score (MOS) values, which correspond in tests to Cisco MOS or ITU P.862 as precise as 97%. More interesting facts to follow – stay in touch!

Share

Tags: , , , , , , , , , , , , , , , , , , , , , , ,

Comments

2 Comments on How to compare two audio files quality wise?

  1. Rob McKeown on Wed, 23rd Mar 2011 02:27

    2. Hi there,

    While I do not fully understand the methods used here (if at all), I’d love to know

    if this could be used to analyze the differences between two recordings

    of a sample played in two different points of a room

    and then recorded by a mic in a fixed position

    i.e. the mic records once with the sound coming from point A

    then records the same sound coming from point B

    could this analyze the acoustic differences?

    Thanks so much, I hope some one still replies to these!

    Rob

  2. admin on Fri, 15th Apr 2011 11:12

    3. Hi,

    Thank you for the question! In your example the “weak point” is that audio is recorded by a microphone, which will introduce additional degradation and may introduce addtional data (noise). However, if we think of an ideal situation when the microphone is of a high quality and there are no side noises in the room, then yes, AQuA will be able to detect the difference between how the audio sounds (“was heard”) from one point of the room and how it sounded (“was heard”) when played from another point.

    A similar case may be when you have a large room or building and have a wireless LAN installed to serve as VoIP carrier, then by tweaking f.e. our Asterisk VQM solution one can analyze in what part of the building the reception of wireless access point is enough and what gives bad quality.

    You are always welcome to contact us direclty via http://ww.sevana.fi web site and we bring you in touch with a relevant person.

    Best Regards,
    Sevana Oy

Tell me what you're thinking...
and oh, if you want a pic to show with your comment, go get a gravatar!