Listening aspects in music rooms

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Introduction

Listening aspects in music rooms = Listening aspects related to room acoustical effects on music

A suggested set of five listener aspects with corresponding physical quantities is presented in http://www.akutek.info/concert_hall_acoustics_files/parameters. In this article a more detailed description of listening aspects, their significance to the perception of music in a room acoustical environment, and their possible interrelations are pursued.  By music rooms we understand any room for music performance or practice, from small rehearsal rooms to big concert halls—any room where acoustics play a significant role to the perception of music. Some of the listening aspects, may well be relevant to performers’ perception of music, too, e.g. reverberance.

When we discuss listener aspects in music rooms, we need to keep in mind that room acoustical effects are inseparable from music in general, since music as phenomenon has evolved in reverberant environment. Music performed in anechoic environment is considered to be exceptions. Reverberant sound heard from a musical instrument is in general a combination of reverberant energy created in the instrument and reverberant energy created in the room. In some instruments, the reverberant energy is mainly in the generator, like the air-column in wind instruments and the string in an electric guitar. In other instruments, like bowed strings, the reverberant energy builds up partly in the strings, partly in the body, before it radiates to the room. Basically, a tone is a reverberation phenomenon, since a tone is created by some kind of feedback, mechanically, acoustically or even electronically (like in the electronic circuits in a synthesizer).

Given the above perspective, it is hardly surprising that room acoustical  effects, such as reverberation, are added artificially to music reproduction such as recordings and broadcasting where sound is picked up closer to the instruments than preferred listening positions.

It’s all about reverb

Room acoustic reverberation, what difference does it make to perception of music?

All aspects appears to be related to room acoustical reverberation (hereafter: reverb) somehow, all depending on temporal, spatial and spectral properties of reverb and of the relationship between direct sound and reverb sound.  For example, reverb has a temporal aspect denoted reverberance, and a group of spatial aspect denoted envelopment. Another spatial aspect, related to early lateral reverb sound, is the Apparent Source Width. The total energy of the reverb makes Loudness, and the balance between early and late reverb energy determines Clarity (at least outside the so-called reverberation radius, Rr).

Liveliness, Vivacity or Animation is suggested to describe the subjective effect of fluctuations in time, space and frequency, all emerging from stochastic processes in the acoustics of any room.

What about direct sound?

One must keep in mind that reverb not always makes a positive difference to perception of music: Whenever there is too much reverb, or just too much early reverb, the direct sound may become inseparable from reverb. As a result, the foreground of musical instants becomes inseparable from the reverberant background, the source becomes inseparable from the room (source not localizable), pitch separation becomes difficult, and coloration may arise. Paradoxically, too much (early) reverb results in loss of Reverberance and Envelopment, because the brain would perceive reverb as distorted direct sound instead of as a series of separate listening aspects. Griesinger has reported from extensive studies of the importance of the direct-to-reverb balance, in the paper trilogy Phase Coherence as a Measure of Acoustic (2010). 

Too much or not too much reverb—the heading still holds: It’s all about reverb.

Reverberance, it is

· The temporal aspect of reverb sound

· A monaural effect, it can be heard in mono sound reproduction, e.g. in mono radio broadcasting

· The musical short-term memory of the room

· Provides a sounding background to a foreground of notes

· Provides sonority, horizontal melody converted into vertical harmony, the current tone is heard on a background of  previous tone

· Adds to the soloist or individual instrument an apparent ensemble effect, where each single instrument plays in unison with a large number of image instruments, though somewhat delayed in time

· Emphasizes Ensemble Unity in contrast to instrument individuality, by creating the impression that all the instruments of an ensemble, although separable, are playing in the same space, thus

· Defines the “arrow of time” in music,

· emphasizing the temporal direction of music,

· dividing music events into past, present and future, by placing present in the foreground and past in the background, assigning musical notes and micro-events to a timeline, adding temporal dimension to the dimensionless note

· the reverb tail always points out the direction of time

· since the decay of reverb is associated with increasing distance to the source, musical events in the past appear more distant than those at the present ones

· in radio broadcasting or other reproduction, present notes will tend to appear close in front of the listener, while past notes appear to fade out  in the far front of the listener (In contrast to the live experience where, present notes appear at stage in front of the listener, while the reverb of past notes seem to move towards the back of the listener, fading away behind the listener)

· Converts on/off into grow and fade: A note starts with no reverb, but gradually grows to become reverberant. When the note ends, the reverb of the note starts to fade. Thus reverb increases the perceptive difference between start and end of a note, and it is a part of the role as a time-arrow, described above. It is possible to imagine a small piece of an-echoic recorded music being played backwards without the listener noticing the wrong direction. However, with the slightest bit of reverb, the wrong direction of time would immediately be noticed.

Envelopment

Apparent Source Width

Loudness (Subjective level of sound)

Clarity

Liveliness

Transparency (for discussion—is it a repeatable listening aspect, or is it just some Hi-Fi-world mumbo-jumbo?)

Engagement (maybe not a listening aspect, but rather an overall )

Relevant link: Music Room Acoustics

 

To be continued

First published 04.05.2012, latest change 08.05.2012

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