Sound reproduction floyd toole pdf download

Between air and electricity traces their quest and sets forward a new theoretical framework, providing historic background on technological and artistic development, and diagrams of concert and performance set-ups. From popular noise musician Merzbow to minimalist classic Alvin Lucier, cult instrument inventor Hugh Davies, or contemporary visual artist Lynn Pook — they all aimed to make audible what was supposed to remain silent. Much time is spent working out how to optimize the acoustics of large rooms, such as auditoria, but the acoustics of small rooms and environments can be just as vital.

The expensive sound equipment of a recording studio or the stereo in a car or living room is likewise rendered useless if the acoustic environment is not right for them. Changes in wa. The Sounds of Early Cinema is devoted exclusively to a little-known, yet absolutely crucial phenomenon: the ubiquitous presence of sound in early cinema.

Whether instrumental, vocal, or mechanical, sound ranged from the improvised to the pre-arranged as in scripts, scores, and cue sheets. The practice of mixing sounds with images differed widely, depending on the venue the nickelodeon in Chicago versus the summer Chautauqua in rural Iowa, the music hall in London or Paris versus the newest palace cinema in New York City as well as on the historical moment a single venue might change radically, and many times, from to Waller, and Rashit M.

Despite the explosion of interest in the "global ," the arts in this period - both popular and avant-garde forms - have too often been neglected. This interdisciplinary volume brings together scholars in history, cultural studies, musicology and other areas to explore the symbiosis of the sonic and the visual in the counterculture of the s. Electric Sounds brings to vivid life an era when innovations in the production, recording, and transmission of sound revolutionized a number of different media, especially the radio, the phonograph, and the cinema.

The s and s marked some of the most important developments in the history of the American mass media: the film industry's conversion to synchronous sound, the rise of radio networks and advertising-supported broadcasting, the establishment of a federal regulatory framework on which U. But what role would this new media play in society?

Celebrants saw an opportunity for educational and cultural uplift; critics feared the degradation of the standards of public taste. Some believed acoustic media would fulfill the promise of participatory democracy by better informing the public, while others saw an opportunity for manipulation.

The innovations of this period prompted not only a restructuring and consolidation of corporate mass media interests and a shift in the conventions and patterns of media consumption but also a renegotiation of the social functions assigned to mass media forms.

Steve J. Wurtzler's impeccably researched history adds a new dimension to the study of sound media, proving that the ultimate form technology takes is never predetermined. The fact case that the perceived spectrum is the result of a central brain 3 Intelligibility of speech as it is influenced by a re- summation of the slightly different spectra at the two ears flection—the essential factor attenuates the potential coloration from lateral reflections 4 Effect of a reflection on the preferred sound quality significantly [34].

If there are many reflections, from of speech—adding an aesthetic touch. All of these disregard certain linear distortions of the ear input signals curves were measured using speech as a signal.

This is the absolute threshold appear to be able to adapt to these situations, and to hear since nothing is perceived for reflections at lower levels. Put differently, it spaciousness [32]. It is evident ness. Throughout listeners reported all of the sound as that we do not yet have all the answers, but it seems clear originating at the location of the loudspeaker reproducing that the human auditory system is well adapted to dealing the first sound; the precedence effect was working. The next higher curve is the level at which listeners reported hearing a change in size or position of the prin- 2.

This was called the image-shift threshold resonances yielded the interesting fact that repetitions of a [32]. In general these changes were subtle, noticeable in A sound lowered the detection thresholds for medium- and versus B comparisons, but in the context of a multiple- low-Q resonances within the sound [7]. This is a quanti- image soundstage one needs to know whether these play- tative confirmation of common experience: live unampli- back effects are likely to be recognized as being distinct fied music sounds better in a room than it does outdoors.

An aesthetic subjective judgment of this attribute a laterally positioned loudspeaker by as much as 10 dB is especially difficult to put a value on, when what was above the direct sound before it is perceived as being as intended by the recording engineer and artists is not loud as the direct sound.

It is important information in the known. In programs such as movies or television, where context of professional audio, but it is irrelevant in the most of the information is presented through the center context of small-room acoustics.

This is not so. It is source or image, simultaneously coexisting with the origi- evident from an inspection of Fig. There is no range of delays or time zone well as spatially separate echo [39], [40]. It is also evident that audible effects begin to be down. Although the original source remains the perceptu- perceived at levels 30 dB or more below the level of the ally louder, spatially dominant source, there is a problem curve that Haas generated, meaning that masking in the because two spatial events are perceived when only one simple sense of rendering other sounds inaudible is not should be heard.

This tells us that, in a public address situa- Haas data are frequently interpreted as if they applied to tion, it is possible to raise the level of delayed sound from music. The threshold curves for other kinds of sounds, especially transient sounds, are very different, as will be seen. It is quite incorrect to assume that the precedence effect is some sort of masking phenomenon which, by blocking out the later arrivals of the signal, prevents the auditory system from being confused.

Quite to the contrary, those arrivals that come in within a reasonable time after the first one actively contribute to our knowledge of the source. Further- more members of the set that are delayed somewhat too long actually disrupt and confuse our perceptions even when they may not be consciously recognized.

If the arrivals are later yet, they are heard as separate events echoes and are treated as a nuisance. If we take from Fig. The shaded area under that curve can be Fig. Progression of thresholds for different audible effects of considered to be the real-world precedence effect fusion a single lateral reflection, as heard in an anechoic space.

Bottom curve—detection threshold [32]. At this level the common sen- zone for speech, within which any reflected sound will not sation was one of spaciousness; all sound appeared to come from be perceived as a spatially separate localizable event. The the location of the first arrived sound.

Next two level as the direct sound. This is how the classic psycho- curves—levels at which listeners were able to identify a second image, at the location of the reflection, coexisting with the prin- acoustic experiments were conducted, but it is improbable cipal image [39], [40].

Top curve—level at which primary and in normal rooms. For reflections at realistically lower lev- secondary images were judged to be equal in loudness [31]. Individual reflections in normal small rooms are not reduced, although the subjective effect is less than would likely to generate multiple images from speech produced be predicted by a perfect energy summation of direct and by a person or reproduced by a loudspeaker.

The direc- reflected sounds [46]. A gibility of speech [47]. In this study the reflection was at single lateral reflection may cause the sound image to be the same sound level as the direct sound, which makes this slightly larger or slightly displaced from the position it a worst-case test.

The fact that it was done in a quiet would have in an otherwise anechoic space, but it remains anechoic chamber means that the signal-to-noise ratio was to be seen if this is noticeable in a multichannel recording. Within the time interval in which strong early Some evidence suggests that even these small effects reflections are likely to occur in listening and control might be diminished by experience during listening within rooms about 15 ms the effects on intelligibility are neg- a given room [42].

A survey of typical listening rooms 3. While this is an issue in large venues, it is evident that natural reflec- tions in small rooms are too low in amplitude and delay to be problems in this respect. More recent investigations found that intelligibility im- Fig. Levels and delays at which a single reflection causes listeners to be disturbed while listening to speech, according to [44], [43].

Shown for comparison are the first six reflections in a typical listening room [48]. Data from Fig. Shaded area— precedence effect fusion zone, defining levels and delays of re- Fig.

Reflections and direct cating that all are well within the fusion zone. Looking at the overall evidence from these ings. This is in the ligibility, and others improve it, with the improvement region of the first sidewall reflection from the front loud- increasing as the delay is reduced.

Front—back symmetry 3. Overall, It is accepted that a reflective sound field is flattering to sounds arriving from the sides, with substantial front and the sound of music. We like to listen in a reverberant back tolerances, are beneficial.

In concert halls the impor- space, rather than outdoors. The question is at what point tance of these sounds is indicated by a measure of the does this positive attribute begin?

Ando has provided lateral energy fraction LF, which correlates well with a some answers. In both concert halls and listening sound that listeners reported as enhancing the sound of rooms reflected sounds arriving from the front or rear do classical music.

Since the early reflections in real rooms not contribute to a positive impression. Note that are effective at reducing the interaural cross correlation the second-image curve is just avoided, indicating that the and therefore contribute to increased preference [50]. In practical fect fusion zone. The inevitable conclusion is that, in natu- audio systems this suggests that reflecting surfaces very ral listening, room reflections are not problems.

In fact, close to a loudspeaker are least beneficial. Of course, a they will need augmentation by recorded reflections be- lack of positive contribution is not necessarily a negative fore listeners are fully gratified. Yet another topic for investigation and, clearly, Preference in This Context program is a variable. The greater the dif- Working with a single reflection allows for intensely ferences in sounds at the two ears, the greater the sense of analytical investigations but, inevitably, the tests must in- clude others in order to be realistic.

With speech, preferred delay for a single reflection at a direct sound [49]. Results are shown for three sound levels tions in a typical listening room [48].

Adapted from [50] Fig. Consequently embodied in several stan- ings, therefore, seem to be remarkably well preserved in dards, and published designs, are schemes to deflect, diffuse, the reflective sound fields of ordinary rooms. There may or absorb at least the first reflections from a loudspeaker. In a continuation of the experiments discussed earlier Section 3. The large changes in the level of reflected sound had only a modest 1—5-dB effect on the absolute threshold or the image- shift threshold of an additional lateral reflection occurring within about 30 ms of the direct sound.

At longer delays the threshold shifts were up to about 20 dB, a clear re- sponse to higher level late-reflected sounds in the increas- ingly live rooms. One of his results is directly comparable with these data. The similarity of the results is remarkable, consider- [50]. Preference scores for two musical motifs as a function of horizontal angle of single reflection, with corresponding measured interaural cross correlation IACC [50].

Remarkably, even attenu- tions and a reverberant decay for several different rooms ating the direct sound had little effect on intelligibility in [53]. The smallest was similar in size to a very large home a sound field with sufficient early reflections.

The findings theater or a screening room m3, 13 ft3. The authors go on to point out word recognition scores [54]. In fact, the effects range from neutral to positive. No single reflection has been shown to be a problem for speech reproduction in small rooms see Table 1. Multiple early reflections con- tribute even more to intelligibility. The differen- Table 1. Reflections in small rooms and perception of speech: report card. Detection and image-shift thresholds as a function of delay for single lateral reflection anechoic chamber; — — — listening room in which all first reflections have been attenuated with 2-inch mm fiberglass board RRF listening room ; same IEC listening room in highly reflective configuration [32].

Image-shift thresholds as a function of delay for single Fig. Absolute detection thresholds for single lateral reflection lateral reflection for two listeners in reflective IEC listening in anechoic chamber for sounds of four different temporal struc- room FT data from [32] and for three listeners averaged in tures: relatively continuous Mozart , mixture of transient and simulation of an IEC room using multiple loudspeakers in large continuous speech , transients with reverberation castanets in anechoic chamber [52].

In speakers inhibit our ability to be persuaded that we are in terms of the precedence effect fusion interval, it is clear the environment incorporated into a recording? At the crete center-channel signals we may invoke plausibility to other extreme, for isolated transient sounds it can be only modify the precedence effect and localize to the moving a few milliseconds.

Mixtures of transient and sustained lips on the screen, sometimes referred to as the ventrilo- sounds, such as speech or castanets with reverberation, are quism effect. We may use naturally occurring early room in between [32]. All is well. Some casual tests suggest that the shapes of the those distance cues. By what rules and measures is it pos- threshold curves are continued in such families of curves sible to achieve both of these conflicting illusions?

We as image shift or second image, as shown in Fig. How- know from experience that it can work, but could it work ever, only a direct investigation of this would provide proof. In the end, we need new measures. One of these would 5. In small listening rooms it seems to be important to All of the analyses of rooms thus far have focused on have guidance about the optimal amplitude or energy re- the effects that rooms have on sounds created within them, lationships between direct and collections of early re- without confronting the essential factor unique to sound flected sounds.

In multichannel systems it is reasonable to reproduction. It is necessary to distinguish between the think that this may differ by channel, depending on the factors related to the perceptions of timbre, direction, dis- primary function, such as front channels versus surround tance, and space generated by real sources of sound in channels, and the application, movies versus music.

When we take to both music and speech sounds, and those occurring photographs under fluorescent or incandescent lighting or naturally in small rooms are, if anything, too low in level outdoors in the shade or direct sunshine, we immediately to have an optimal effect.

This could be interpreted as are aware of color balance shifts—greenish, orangish, blu- providing justification for multichannel audio, to add more ish, and so on. Yet in daily life we automatically adjust for reflections, and implying that natural room reflections are these and see each other and the things around us as if not likely to detract from reproduced sounds incorporating under constant illumination.

We adapt to low and high reflections. There are limits—very col- Indeed, numerous early reflections have a positive cu- ored lighting gets our attention, we cannot look into the mulative effect on speech intelligibility. In terms of image sun, or see in the dark, but over a range of typical circum- localization, the precedence effect appears to hold in the stances we do remarkably well at maintaining a comfort- presence of many reflections, and our distance perception able normalcy.

Most adaptation occurs on a moment-by- improves. Distortions of image size and position appear to moment basis, and is a matter of comfort—bringing our be borderline issues. From the perspective of sound qual- perception of the environment to a more acceptable con- ity, multiple reflections reduce the effects of comb filter- dition.

In the extreme, adaptation, habituation, or acclima- ing good and enhance our perception of resonances tization, whatever we call it, can be a matter of survival good for the music, and bad only if the resonances are in and a factor in evolution. If managed properly, room reflections Earlier, in the contexts of precedence effect angular could contribute to our impressions of spaciousness. The localization , distance perception, and spectral compensa- audibility of an individual early reflection in a recording is tion timbre , it was stated that humans can track complex not greatly influenced by collections of early reflections in reflective patterns in rooms and adjust their processes to a room, but we have no data on whether that recorded compensate for much that might otherwise be disruptive in reflection, and others that accompany it, are perceived as our perceptions of where sounds come from, and of the contributing to the impressions of distance, for example, true timbral signature of sound sources.

This appears to be intended by the recording. We need to know the circumstances under ing notions of what is or is not plausible. At what point does sound quality, comes from experiments in which three J. In the first experiment listeners completed the the room to a considerable extent. If residual effects of the evaluation of the three loudspeakers in one room before room are predominantly at low frequencies, these differ- moving to the next one.

All tests were double the room [56]. In each room, three loudspeakers were evaluated in There are everyday parallels to this. We carry on con- three locations for each of three programs. The whole versations in a vast range of acoustical environments, from process was repeated, resulting in 54 ratings for each of cavelike to the near anechoic, and while we are certainly the 20 listeners.

The result from a statistical perspective aware of the changes in acoustical ambience, the intrinsic was that: timbral signatures of our voices remain amazingly stable.

Clearly we have a paradox to resolve miliar with—adapted to—the room they were in and, this as we look for the features of the musical sound that give done, were able to judge the relative merits of the loud- it sufficient robustness to survive its strenuous voyage to speakers accurately.

Since they were given the opportunity its listeners, and as we seek the features of the transmis- to adapt to each of the four rooms, they were able to arrive sion process itself that permit a cleverly designed auditory at four very similar ratings of the relative qualities of the system to deduce the nature of the source that produced loudspeakers.

Then, using the same binaural recordings that so faith- So we humans manage to compensate for many of the fully replicated the results of the live listening tests, an- temporal and timbral variations contributed by rooms, and other experiment was conducted. Because adap- cated in each of the loudspeaker positions in each of the tation takes time, even a little, there is the caveat to ac- four rooms.

Thus in this experiment the sound of the room ousticians not to pay too much attention to what they hear was combined with the sound of the loudspeakers in ran- while moving around—stop, or sit down and listen.

What do we have the option of changing, and It appears therefore that we can acclimatize to our lis- what should we simply leave alone? It is as if we can separate the to compare, listeners sat down in four different rooms and sound of a spectrum that is changing the sounds from the reliably rated three loudspeakers in terms of sound quality.

If that and loudspeaker locations within it. This appears to be is possible, it suggests that by building those properties related to the spectral compensation effect noted by Wat- into a loudspeaker, one may have ensured that it will kins [36]—[38]. There were, and almost all Fig. This listening location for a loudspeaker in three different po- thought-provoking observation has powerful implications sitions in a small room [58].

Below about Hz the on how we conduct listening tests, especially when direct frequency response is dominated by loudspeaker position, comparisons are involved—are we listening to differences whereas at higher frequencies the measurements follow a before or after adaptation?

Are the differences being re- similar pattern. The acoustical explanation is the domi- vealed in the listening test the same qualities of sound that nance of room modes and standing waves at low frequen- would be perceived by us in a normal listening situation?

In between is a It seems safe to take away from this a message that transition zone, the middle of which, in large rooms such listeners in comparative evaluations of loudspeakers in a as concert halls and auditoriums, would be defined as the J. Calculation of the Schroeder in Section 6—that our judgments of sound quality are frequency assumes meaningful reverberation times and a somewhat independent of the complications of room re- strongly diffuse sound field.

As we know, in small rooms flections—is challenging. We will look closely at this, these are mismatched concepts, so the calculations are because the consequences are profound. However, the transition region Let us begin by attempting to understand the nature of is real, and it is necessary to take different approaches to the sounds arriving at the ears of listeners in rooms.

In position in a room, calculated from many anechoic mea- concert halls it is at the bottom of the useful frequency surements made on horizontal and vertical orbits around a range, and low-frequency room resonances cease to be loudspeaker [58]. This loudspeaker had good on-axis be- problems.

As rooms shrink, the transition frequency rises, havior, but deteriorated off axis. It did not have constant, explaining why, in cars, the cabin is the dominant factor or even smoothly changing directivity.

The result is that over much of the frequency range. The energy sum of all 7. Above the transition frequency it turns of the direct sound and many reflections. Steady-state out to be an excellent fit to the curves shown in Fig. Visually alarming irregularities in measurements are listening room, which in essential respects was frequently not heard see Section 2.

This is the fre- intended to be representative of typical domestic listening quency region within which all of the previous discussions spaces. It had carpet on the floor, drapes, furniture, book- of reflections apply, and where the bulk of adaptation, cases, tables, and so on. Since this example, numerous precedence effect, and the like occurs. The idea expressed other measurements have been made with different loud- Fig. No spectral smoothing [58]. The predictions and how long it has been since it had previously been have been very close approximations to the real measure- auditioned, the rating of any individual loudspeaker could ments [48].

While interesting, this can only be of long- move up or down the rating scale. The movement is usu- term value if it correlates with subjective evaluations.

Be- ally not large, but it is a change that the statistical analysis cause a room curve is a nonanalytical combination of all regards as uncertainty about the rating, reducing the sounds from all directions, at all times, it would be sur- correlation.

To overcome this, all loudspeakers must be evaluated in From anechoic measurements on a loudspeaker system one continuous test, with each product being compared to it is possible to anticipate the direct, early reflected, and every other product. When this was done with a group of late reflected sounds that arrive at a listening position in a 13 bookshelf loudspeakers, the correlation improved to typical small room. If those measured sounds are the ones 0. It is clear that there is a way to translate of sound quality—a sound quality, or preference, rating.

In the context of loudspeaker sound And there is more. The excellent correlations mentioned quality, it is something that few have attempted. With less data the correlations were less good. No single curve, anechoic or in many loudspeakers, and have examined the results of room, alone was adequate, although the axial response double-blind listening tests performed on these products. Early in this paper it was noted that rever- evaluations [58].

As subjectively interpreted, a smooth, beration is not a dominant factor in what we hear in small flat, wide-band axial frequency response, combined with rooms, and here it is no surprise to find that the sound similarly well-behaved off-axis responses, up to and in- power output from a loudspeaker is, alone, an imperfect cluding sound power, appeared to be the desirable pattern.

In 7. Obviously an empty room is not a comfort- stricted such as one-third octave frequency resolution. The Using more recent psychoacoustic knowledge, the new furnishings and paraphernalia of life tend to bring normal models examined much smaller details in the raw mea- living spaces into familiar acoustical territory.

A handbook of acoustics and sound system design for the church. The Art of Sound Reproduction. Designed to make life a little easier by providing all the theoretical background necessary to understand sound reproduction, backed up with practical examples. It can get somewhat technical at points, but the author does a great job at making complex matters accessible and clear to a general : James Larson.

In sound reproduction the situation is different. I have known Floyd for years, and I can tell you that his knowledge of the subject of "Sound Reproduction," is second to none.

Sound Reproduction: Loudspeakers and Rooms is a relatively nontechnical compendium of Toole's work on small-room acoustics, loudspeakers, and listening.

Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms, Third Edition explains the physical and perceptual processes that are involved in sound reproduction and demonstrates how to use the processes to create high-quality listening experiences in stereo and multichannel formats. Handbook of sound reproduction. Written in EnglishPages: Sound Reproduction book. Sound recording and reproduction is an electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound two main classes of sound recording technology are analog recording and digital recording.

Acoustic analog recording is achieved by a microphone diaphragm that senses changes in atmospheric. Multichannel loudspeaker reproduction is more obvious, because each channel and its associated loudspeaker create an independently localizable sound source, and interactions between multiple loudspeakers create opportunities for phantom sources and impressions of movement.