Conventional high frequency phase response specifications of audio electronics, although easily acquired with standard available instruments, are misleading. The absolute phase value contains two components, frequency independent delay, and frequency dependent delay. It is only the second component, frequency dependent delay, which alters the shape of the audio waveform thus altering the characteristic sound of the processed signal. To be meaningful, phase data must be presented as two separate values or graphs, deviation from linear phase and group delay. The first is a modified phase graph, where the frequency independent delay is subtracted out, leaving only that part of the phase transfer function which alters the shape of the audio waveform. The group delay graph shows delay vs. frequency for the spectral components of a complex waveform. This is not a new subject or discovery, but one which needs more of our audio industry's attention. RF, microwave, and acoustic phase measurements have routinely incorporated delay corrections, but conventional phase measurements of audio electronic devices have not corrected for frequency independent delay which we propose must be done to make phase specifications meaningful.
https://www.aes.org/e-lib/browse.cfm?elib=5032
Click to purchase paper as a non-member or login as an AES member. If your company or school subscribes to the E-Library then switch to the institutional version. If you are not an AES member and would like to subscribe to the E-Library then Join the AES!
This paper costs $33 for non-members and is free for AES members and E-Library subscribers.
Learn more about the AES E-Library
Start a discussion about this paper!
