Now Reading
Audio Musings by Sean Olive: Audio’s Circle of Confusion

Audio Musings by Sean Olive: Audio’s Circle of Confusion

2023-04-13 04:01:10

Audio’s “Circle of Confusion” is a time period coined by Floyd Toole [1] that describes the confusion that exists inside the audio recording and copy chain as a result of lack of a standardized, calibrated monitoring setting. Immediately, the circle of confusion stays the only largest impediment in advancing the standard of audio recording and copy.

The circle of confusion is graphically illustrated in Determine 1. Music recordings are made with (1) microphones which can be chosen, processed, and blended by (2) listening by skilled loudspeakers, that are designed by (3) listening to recordings, that are (1) made with microphones which can be chosen, processed, and blended by (2) listening by skilled screens…… you get the thought. Each the creation of the artwork (the recording) and its copy (the loudspeakers and room) are trapped in an interdependent round relationship the place the standard of 1 depends on the standard of the opposite. Because the playback chain and room by which recordings are monitored usually are not standardized, the standard of recordings stays extremely variable.

Creating Music Recordings By way of An Uncalibrated Instrument

A random sampling of ones personal music library will rapidly verify the variation in sound high quality that exists amongst totally different music recordings. Aside from audible variations in dynamic vary, spatial imagery, and noise and distortion, the spectral stability of recordings can differ dramatically when it comes to their brightness and significantly, the standard and amount of bass. The magnitude of those variations means that one thing aside from variations in creative judgment and good style is on the root reason behind this drawback.

The most probably culprits are the loudspeakers and rooms by which the recording have been made. Whereas there are numerous glorious skilled near-field screens within the market in the present day, there are not any trade pointers or requirements to make sure that they’re used. The lack of meaningful, perceptually relevant loudspeaker specifications makes the superb loudspeakers troublesome to establish and separate from the actually mediocre ones. To make issues worse, some misguided recording engineers monitor and tweak their recordings by low-fidelity loudspeakers considering that this represents what the common shopper will hear. Since loudspeakers might be mediocre in an infinite variety of methods, this follow solely ensures that high quality of the recording will likely be compromised when heard by good loudspeakers [1]. That is very counterproductive if we need to enhance the standard and consistency of audio recording and copy.

One other vital supply of variation within the recording course of stems from acoustical interactions between the loudspeaker and the listening room [1]-[3] Under 300-500 Hz, the location of the loudspeaker-listener could cause >18 dB variations within the in-room response on account of room resonances and inserting the loudspeaker in proximity to a room boundary.

Proof of acoustical interactions has been effectively documented survey of 164 skilled recording studios the place the identical high-quality, manufacturing facility calibrated monitored was put in [4]. Determine 2 exhibits the distribution of in-room responses measured on the main listening location the place the recordings are monitored and blended. The 1/3-octave smoothed curves present a fairly tight ± 2.5 dB variation above 1 kHz. Nevertheless, under 1 kHz, variation within the in-room response will get progressively a lot worse at decrease frequencies. Under 100 Hz, the in-room bass response can differ as a lot 25 dB among the many totally different management rooms! You needn’t look any additional than right here to know why the standard and amount of bass is so variable among the many recordings in your music library.

Evaluating Loudspeakers When the Recording is a Nuisance Variable

Loudspeaker producers are additionally trapped within the circle of confusion since music recordings are utilized by listening panels, audio reviewers, and shoppers to finally choose the sound high quality of the loudspeaker. The issue is that distortions within the recording can’t be simply separated from these produced by the loudspeaker. For instance, a recording that’s too vivid could make a boring loudspeaker sound good, and an correct loudspeaker sound too vivid [5]. A evaluation of the scientific literature on loudspeaker listening assessments signifies that recordings are a critical nuisance variable that have to be rigorously chosen and managed within the experimental design and evaluation of take a look at outcomes.

At Harman Worldwide, we attempt to decrease loudspeaker-program interactions in our loudspeaker listening assessments by utilizing well-recorded packages which can be equally delicate to distortions present in loudspeakers. Listeners turn into intimately accustomed to the sonic idiosyncrasies of the totally different packages by intensive listener training and participation in formal assessments. In every trial of a loudspeaker take a look at, the listener can swap between totally different loudspeakers utilizing the identical program, which permits them to raised separate the distortions in this system (that are fixed), from the distortions within the loudspeaker.

By way of 25+ years of well-controlled loudspeaker listening assessments, scientists have recognized the essential loudspeaker parameters associated to good sound, which might be quantified in a set of acoustical measurements [6],[7] By making use of some statistics to those measurements, listeners’ loudspeaker preferences might be predicted [8]. The bass efficiency of the loudspeaker alone accounts for 30% the listener’s general desire ranking. Good bass is important to our enjoyment of music, which sadly is a frequency vary the place loudspeakers and rooms are most variable (see Determine 2). Controlling the habits of loudspeakers and rooms at low frequencies is important to attaining a extra constant high quality of audio recording and copy. Fortuitously, there are know-how options in the present day that present efficient management of acoustical interactions between the loudspeaker and rooms.

Breaking the Circle of Circle of Confusion

As Toole factors out in [1], the important thing in breaking the circle of confusion lies within the palms of the skilled audio trade the place the artwork is created. A significant customary that outlined the standard and calibration of the loudspeaker and room would enhance the standard and consistency of recordings. The identical customary might then be utilized to the playback of the recording within the shopper’s dwelling or car. Lastly, shoppers would have the ability to hear the music because the artist supposed.


[1] Floyd E. Toole, Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms, Focal press (July 2008).

[2] Floyd Toole, “Loudspeakers and Rooms: A Scientific Evaluate,” J. Audio Eng. Soc., Vol. 54, No. 6, (2006 June). A free copy of this paper might be downloaded here

See Also

[3] Sean E. Olive and William Martens “Interaction Between Loudspeakers and Room Acoustics Influences Loudspeaker Preferences in Multichannel Audio Reproduction,” offered on the 123rd Conference of the AES, preprint 7196 (October 2007).

[4] Aki V. Mäkivirta and Christophe Anet, “The Quality of Professional Surround Audio Reproduction, A Survey Study,”nineteenth Worldwide AES Convention: Encompass Sound – Methods, Expertise, and Notion (June 2001).

[3] Todd Welti and Allan Devantier, “Low-frequency Optimization Utilizing A number of Subwoofers,” Audio Eng. Soc., Vol. 54, No. 5, (Could 2006). A free copy of this paper might be downloaded here

[4] Sean E. Olive, John Jackson, Allan Devantier, David Hunt, and Sean Hess, “The Subjective and Objective Evaluation of Room Correction Products,” offered on the 127th AES Conference, New York, preprint 7960 (October 2009).

[5] Sean E. Olive,”The Preservation of Timbre: Microphones, Loudspeakers, Sound Sources and Acoustical Spaces,”eighth Worldwide AES Convention: The Sound of Audio (Could 1990)

[6] Floyd E. Toole, “Loudspeaker Measurements and Their Relationship to Listener Preferences: Half 1,” J. Audio Eng. Soc., Vol. 34,No.4, pp.227-235, (April 1986). A free copy of this paper might be downloaded here

[7] Floyd E. Toole, “Loudspeaker Measurements and Their Relationship to Listener Preferences: Half 2,” J. Audio Eng. Soc., Vol. 34, No.5, pp. 323-348, (Could 1986). A free copy of this paper might be downloaded here

[8] Sean E. Olive, “A Multiple Regression Model for Predicting Loudspeaker Preference Using Objective Measurements: Part II – Development of the Model,” offered on the 117th Conference of the AES, preprint 6190 (October 2004).

Source Link

What's Your Reaction?
In Love
Not Sure
View Comments (0)

Leave a Reply

Your email address will not be published.

2022 Blinking Robots.
WordPress by Doejo

Scroll To Top