Concert Hall

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RECOMMENDATIONS FOR ACOUSTIC RENOVATIONS

ODESSA PHILHARMONIC ORCHESTRA
Odessa, Ukraine

Artec Report No 7239
Artec Project No 3363

Date: 18 December 1996

Distribution:

Odessa Philharmonic Orchestra -Odessa, Ukraine
Maestro Hobart Earle

American Friends of the Odessa Philharmonic Orchestra
Elizabeth Flemer, President

Swiss Friends of the Odessa Philharmonic Orchestra
Paul M. Van Marx (Switzerland)

ECONOMIC FEASIBILITY STUDIES      THEATRE CONSULTING      ACOUSTICS
114 WEST 26 STREET NEW YORK NY 10001-6812 (212)242-0120 FAX (212) 645-8635

Table of Contents

Photograph of Russell Johnson in Philharmonic Hall, Odessa
Executive Summary
Introduction
Existing Condition of Philharmonic Hall
Comments of Musicians that Perform in Hall
Acoustic Measurements
Observations of Acoustics and General Observations
Recommendations for Renovation Goals
Conclusions
Appendix I
Appendix II
Comparison to the Musikvererinssaal, Vienna and Symphony Hall, Boston
Appendix III
Executive Summary

Artec Consultants Inc. visited Odessa Philharmonic Hall in the City of Odessa, Ukraine from 11 September to 16 September 1996 at the request of Maestro Hobart Earle, Music Director of the Odessa Philharmonic Orchestra. The purpose of Artec’s visit was to inspect the existing condition of the Philharmonic Hall, take acoustic measurements, listen to the orchestra rehearse and perform the Hall and make recommendations for acoustical improvements.

Philharmonic Hall is a fine and well preserved example of turn of the century architectural character of Odessa and of the Venetian Gothic style. As with aged buildings, there are areas that need attention beyond that of routine maintenance. With restoration, the Odessa Philharmonic Hall and its ancillary spaces could rival the great performance halls of Europe in architectural distinction and provide a more functional home for the Orchestra.

After preliminary discussions between Artec and the Maestro, most of the draperies I surrounding the stage were taken down. This provided a substantial Improvement to the acoustics of Philharmonic Hall in the opinion of the Maestro, most of the orchestra members and several other observers. When compared to other concert rooms, the Philharmonic Hall (with the draperies removed) has fine acoustics for symphonic orchestra and can rate among the best in Europe with full restoration.

The improvement that is possible to the acoustics will realize important incremental changes toward the full potential of the Hall. To summarize, there are four areas that require attention for the immediate benefit of the orchestra and overall acoustics:

1) Improvements to the acoustic isolation from noise outside the Hall and improvements to the low-frequency response of the room’s acoustics.

2) Restoration and improvement of the stage and stage riser system to enhance on-stage communication between performers and between performers and the audience.

3) Redesign of the stage lighting system, including enhancement of infrastructure, if needed. To whatever degree possible, this should integrate with the historic architecture of the Hall.

4) Repairs to the heating and ventilation systems to allow usage of the room throughout the year. This should be done in a way that does not damage the acoustics or add noise to the room.

In addition, general restoration of the room finishes would be an architecturally desirable improvement. Normal usage of the facility has resulted in the need for thorough cleaning of the walls, murals and plaster work.

Introduction

Artec Consultants Inc. visited Odessa Philharmonic Hall in the City of Odessa, Ukraine from 11 September: to 16 September 1996 at the request of Maestro Hobart Earle, Music Director and Principal Conductor of the Odessa Philharmonic Orchestra. Mr. Russell Johnson, Chairman of Artec Consultants, was the principal acoustician, and was assisted by Mr. Damian Doria, Artec’s Director of Acoustic Consulting Services.

On September 12, Artec first visited the Philharmonic Hall and following a cursory tour of the facility attended a rehearsal of Mahler’s Sixth Symphony for the Philharmonic Orchestra’s season opening concert on September 14. On September 13 and 14, similar rehearsals were attended and recorded, and various meetings with the orchestra personnel, building management, Philharmonic Society, Odessa building officials and the Odessa press took place. Closer inspections of the room interior and finishes, and ancillary spaces were made. Acoustic measurements were made of the Philharmonic Hall on the evening of September 13 for later analysis at Artec’s New York acoustics laboratory.

On the evening of September 14, the official opening concert of the Orchestra’s season occurred. Digital recordings of the performance were made while seated with the audience in the room for later reference and comparison with recordings of the rehearsals for which there were few people in the audience.

Acousticians have developed a language for describing “good acoustics” that relate to the subjective impressions of critical listeners such as musicians and seasoned patrons of the Arts. A discussion of the traits of an excellent concert room is located in Appendix. The remainder of this report discusses the findings of Artec’s visit in terms similar to those in Appendix I.

Existing Condition of Philharmonic Hall

Philharmonic Hall is a fine and well preserved example of turn of the century architectural character of Odessa and of the Venetian Gothic style. As with all aged buildings, there are areas that need attention beyond that of routine maintenance. In some areas finishes have started to crumble and most surfaces of the Concert Hall are in need of cleaning. With restoration, the Odessa Philharmonic Hall and its ancillary spaces could rival the great performance halls of Europe in architectural distinction and provide a more functional home for the Orchestra

The Odessa Philharmonic Hall has massive structure and walls, while housing only 1150 seats. This makes it relatively easy to achieve goals such as strength, low frequency impact, warmth of tone and freedom from outside noise sources. This same quality sometimes causes problems such as having too loud or harsh a sound, too much clarity, or lack of reverberance. However, these problems are not present in the Philharmonic Hall. The classic “shoe box” shaping of the audience chamber helps provide a sense of envelopment through strong lateral reflections of sound energy that arrive at listeners’ ears early in time. The substantial height of the room allows for sufficient reverberation for orchestral performance.

If one compares the basic architecture of the Odessa Philharmonic to two of the world’s most acclaimed concert calls, the Boston Symphony Hall and Vienna’s Grosser Musikvereinssaal, one quickly sees the similarity of overall dimension, shape and materials. Comparison data and plans of the main levels for all three halls are included in Appendix II.

The acoustic quality of the Philharmonic Hall changes when an audience is present. The audience (approximately 1100 persons) adds a great amount of acoustically absorptive surface to the room. At the main level seating, much of the orchestras sound grazes over audience, and is absorbed. The overall strength and level of reverberance is reduced when an audience is present. Low frequency strength is reduced slightly, and the mid and high frequencies are considerably reduced. Overall, this results in a better balance between low and high frequencies than when the hall is empty, but with reduced impact of sound. This is particularly noticeable in the low frequencies of the bass and celli sections.

Comments of Musicians that Perform in Hall

Artec had the benefit of meeting with several of the musicians from the Philharmonic Orchestra. Their comments are summarized as follows:

Second Violin:
“I feel that the walls do not reflect enough sound. I don’t hear myself playing.”

String Bass:
“I felt that there was much better balance on stage with the curtains removed.”

Concert Master:
“It is very hard to hear the other musicians on the stage, compared to other halls where the Philharmonic Orchestra has performed.”

Bassoon:
“With the curtains removed I can hear my instrument much better and it is easier to play.”

French horn:
“With the curtains removed we hear an answer from the auditorium that we didn’t -hear before.” (This musician considered this to be an improvement.)

Percussion:
“I can hear the other players in my section better with the curtains removed.”

Maestro Earle:
“The percussion section plays very loudly with the curtains removed. They are used to having to play very hard and will take some time to get used to the change.”

As is obvious from the above comments, most of the musicians were focused on the removal of the curtains from around the stage area. Most musicians agreed that there was a significant change from removing the curtains and that this change was for the better. While we would have liked to learn more about the musician’s opinions of other aspects of the hall’s acoustics, the orchestra was just getting accustomed to the hall without curtains and couldn’t yet comment on the hall more specifically. Maestro Earle should continue to ask the impressions of the musicians as they become more accustomed to hearing each other and the room better.

Acoustic Measurements

While it is easier to discuss the acoustics of different halls using more subjective terms such as warmth, definition, loudness, balance, etc. it is useful to compare halls based on more objective, measurable quantities. Three common measures of the acoustics of a room are the Reverberation Time (T60), Early Decay Time (EDT) and Clarity Index (C80).

Reverberation Time (T60) is the time it takes for a loud sound to decay to inaudibility after its source is stopped. The source of the sound may be a special “white” or “pink” I noise source, or an impulsive noise like a gunshot or balloon burst. T60 is commonly reported as an average of the 500 and 1000 Hertz octave bands.

Early Decay Time (EDT) is similar to Reverberation Time, in that it measures the time of decay, but concentrates on only the first 10 decibels (a measure of loudness) of the decay. The time for the first 10 decibels to decay is multiplied by six to make EDT comparable to T60. It more closely represents how people perceive reverberation than T60, particularly when listening to sources that do not fully decay to silence. Music, without long rests, is an example of such sound that does not fully decay in an audible manner.

Clarity Index (C80) measures the ratio between sound energy reaching a listener in the first 80 milliseconds of an impulse sound and the sound reaching a listener after 80 milliseconds. This is roughly the ratio of “early” energy, which is made up of the direct sound and first several reflections from side walls, floor and ceiling, and the “late” energy sound that is part of the general reverberance of the room. It is related to how clearly audible a sound may be heard over the running reverberance.

Unoccupied measurements of the Odessa Philharmonic Hall resulted in the following data:

 

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Graphs of this data are present in Appendix II.
Observations of Acoustics and General Observations

Artec attended several rehearsals and one performance of the Odessa Philharmonic Orchestra in the Philharmonic Hall. It was a great pleasure to attend these rehearsals and performances, as the Hall is quite good and the orchestra, under Maestro Earle’s baton played exceedingly well. The curtains surrounding the stage had been mostly removed prior to our arrival, so there was no opportunity to hear the hall and stage in their less reverberant condition.

Our observations of Philharmonic Hall can be summarized as follows:

a) Outside noise (primarily from autos) intrudes upon performances and rehearsals. Aside from the obvious distraction that may occur from outside noise and the impossibility of making fine recordings, noise is of dramatic consequence to the acoustics of a performance space. Artec has studied noise in concert halls for many ears and drawn some conclusions that have proven true in new concert halls and renovations of existing ones:

Noise:

1) Reduces the dynamic range for the orchestra,
2) Limits audibility of quiet passages for the audience,
3) Reduces on-stage communication between performers,
4) Impacts balance between sections of the orchestra,
5) Reduces the perception of reverberance and spaciousness,
6) Reduces clarity and perceived loudness.

As buildings age and settle, it is normal for cracks to develop at masonry joints that allow some noise leakage from the outside. The roof of Philharmonic Hall is not airtight (nor should it be, since the wood construction needs to ventilate to prevent rot). However, the primary path through which noise enters the Hall is through the stained glass windows, including the ones covered with wood.

b) Low frequency impact in the Philharmonic Hall is less than optimal. Performances suffer in several ways as a result of this -reduced Impact, reduced envelopment, less clarity for pizzicati, less warmth of tone for double bass, more difficult balance between sections of the orchestra, and more difficult ensemble for players.

More than one element of the hall contributes to the above stated acoustic shortcomings of the Hall. Principal factors (in the order of importance) are:

1) The absorptive curtains placed around the orchestra (during our visit, most of the r curtains were removed, making the windows a more significant factor),

2) The five large stained-glass windows,

3) The seating for the audience, which has upholstered backs and seat bottoms,

4) Relatively thin ceiling materials.

c) The present stage and risers do not allow sufficient flexibility to arrange the seating of the orchestra as the size of orchestra or program material varies. The overall space on the stage is limited by the “tunnel” passing across the upstage end of the platform. The tunnel infringes on the stage both in plan and elevation, limiting the available area for the orchestra to be seated and protruding vertically too high to serve as part of a changeable stage riser system. The higher elevation of the tunnel roof also prevents using that area for storage of pianos or other instruments that take up stage area even when not used as part of the performance. This was very clearly demonstrated by the larger orchestra present for the Mahler Symphony No.6 during our visit. A small area in the violas to brass sections was crowded with players.

The present stage flooring is disintegrating with age and wear. While not detrimental to the acoustics, this presents a splinter hazard and subjects the Steinway Concert Grand Piano to unfortunate stress as it is rolled between its storage and play positions. It is also of interest to study the appropriate height for the downstage edge of the stage above the first row of audience seating, with the hope of improving sightlines in the first several rows.

d) The present stage lighting is poor. We believe that the available lighting instruments and power capacity of the building are being used effectively, but still fall short of satisfactory lighting for rehearsals and orchestras. This impacts the quality and impression of performances -performers have a difficult time reading their parts and the audience doesn’t see the orchestra as clearly as they should. While this does not result in an acoustic problem at this time, new lighting instruments and dimming systems must meet basic acoustic criteria. Lights should I’ not hum or buzz and should not be suspended from the structure in such a way to damage the stage acoustics (introducing new solid beams or trusses, for example).

e) The present heating, ventilating and air conditioning (HV AC) system for the Philharmonic Hall does not meet comfort standards during most seasons. In winter, the hall is sufficiently cold to make it uninhabitable. In summer, it is not possible to keep the room cool without leaving windows open and thereby allowing too much noise to intrude upon performances. This reduces the concert experience even in months when the building is not too cold to inhabit. It could effect the health of the –musicians and is damaging to the pianos and other instruments stored year round in the hall.

Recommendations for Renovation Goals

It is important to note here the basic structure of the Philharmonic Hall is no less good then most great concert halls of the world. The massive masonry walls and plaster finishes, general dimensions and shape of the room, and performer / audience relationship all contribute to excellent acoustics. Any of the modifications we recommend herein will provide important incremental improvements to the overall acoustics.

Our recommendations are as follows:

1. Reduce or eliminate outside noise intrusion to the Hall and improve the low-frequency impact of the room acoustic.

As buildings age and settle, it is normal for cracks to develop at masonry joints that allow some noise leakage from the outside. The roof of Philharmonic Hall is not airtight (nor should it be, since the wood construction needs to ventilate to prevent rot). However, the primary path through which noise enters the Hall is through the stained glass windows, including the ones covered with wood.

Sound passes through the glass itself. Secondly, sound leaks through the several panels of glass (both the inner stained glass and outer clear glass) that have been broken and around the mortar joints in the stained glass. A lesser, but significant, path for noise is around the joints between the glass panels and lead frames. Only an airtight seal will improve this. This may be improved by covering the windows with well-sealed wooden panels.

Sealing any holes in the ceiling that are not used for ventilation will improve isolation from noise at the roof such as aircraft or rain. Sound baffles can be added to the ventilation openings in the roof to limit the amount of outside noise that enters the attic space without preventing ventilation of that area. Further improvement to the isolation can be achieved by adding acoustic seals to all the doors entering and exiting the Hall.

Low-frequency impact would be improved greatly by covering the stained glass windows with heavy wood panels, though some care must be taken to preserve the stained glass windows. As mentioned earlier, the seats are another factor in the weak low-frequency response. The seats are not original to the Hall in its use as a stock exchange or in its early use as a concert hall. This is conformed by historical photographs of the hall kept by the Philharmonic Society. It will be desirable for acoustic and aesthetic reasons to replace the seating in the next several years. We may assist you in selecting an appropriate seat design at that time.

The remaining loss of low-frequency sound is through the ceiling. It is not likely that the ceiling may be made more massive within the existing structure of the Hall. Large openings in the ceiling for ventilation limit the ultimate ability of the ceiling for reflecting low frequencies, reducing the efficacy of adding mass. This is a limitation that can not be overcome within the historic architecture of the facility. However, substantial improvements to the room acoustic would be realized by covering the windows, replacing the seats and general improvements in the sound isolation of the Hall.

2. Reconfigure and Restore the Stage and Surrounding Space:

A new stage riser system will assist in spacing performers and elevating the brass, winds and percussion to allow easy projection of their sound. Brass and winds did not sound too loud in the Hall during our visit, so we do not believe that balance problems would be created by introducing a more extensive riser system.

A flexible system of stage risers will improve on-stage communication and potentially increase clarity and balance between sections of the orchestra for the audience. This may be best achieved through the use of portable platform risers with adjustable height legs and the ability to reconfigure the platforms without significant alteration to their structure. It would be advantageous to have a system of risers capable of seating orchestras of different sizes for different works and to allow the violins to be grouped together or organized in antiphonal seating. Clearly, the range of possible seating arrangements that would be useful can be numerous. Also, sightline issues and other uses of the stage must be considered as reconfiguration is undertaken. Artec will work with you and the orchestra to determine the detailed stage and riser design.

3. Redesign the Stage Lighting System:

We advise that a study be made of the power capacity of the present service to the building and determination made whether this can be extended to meet your requirements. Following that study, Artec’ Performance Lighting personnel can (as a separate project) assist you in developing a lighting scheme that will improve the on stage score reading and make the performers more visible to audience members. As we discussed during our visit, it may be possible to use an array of chandeliers with integrated stage lighting to fit into the existing architecture, restore some of the historical appearance of the hall and improve stage lighting.

Artec can also make basic recommendations for the types of fixtures and dimming systems that will not create noise in the Hall. We would be pleased to review and advise of the room acoustic impact of introducing new types of fixtures, chandeliers or lighting trusses over the stage.

4. Repair the Heating and Ventilation System

Artec can assist in keeping noise from any new HV AC system from intruding upon performances. We can not, however, engineer the HV AC system. We strongly recommend that an expert in heating and cooling systems be contracted to provide recommendations for making efficient use of the available heat from the City, improving the thermal insulation of the building, and providing some form of supplemental heating for periods when the City can not provide sufficient heat to the building.

Conclusions

The findings and recommendations contained in this report should be a foundation for your subsequent planning, development of detailed design and execution of renovations for the Philharmonic Hall in Odessa. Artec will be pleased to discuss the findings of this report at length, clarifying our recommendations wherever necessary.

The intention of our recommendations is not to be a complete design. Any responsible renovation of such a fine and historic building requires detailed consideration of the existing infrastructure of the building (engineering) and sensitivity to its heritage (architectural design and approval of civic groups and societies). There are also specific acoustic concerns for the arrangement of performers and audience, as well as the structural, electrical and mechanical systems of the building that can only be expressed as a full renovation plan is developed.

APPENDIX I: Acoustical Attributes of Concert Halls

We outline here some basic acoustics goals for orchestral performance and recording spaces, and define a vocabulary. When designing a new concert hall or renovating an existing one, we refer to a general set of goals that constitute the overall acoustics:

1. Appropriate loudness, strength, intensity, impact, body, power, fullness. Generally, in a concert hall larger than about 1600 seats the natural room loudness is rarely if ever too great for
Mendelssohn, Beethoven, Mahler, Stravinsky and most of the standard orchestral repertoire, and never too great for chamber music and recitals. The goal for orchestral and choral concerts is to achieve the appropriate strength, while allowing sufficient amounts of sound to be absorbed.

2. Appropriate clarity and definition, but with sufficient richness and blend. Certain types of music sound best with a great deal of clarity and definition, and other works sound best with less definition. A concert hall should provide a range of definition for the gamut of music that will be presented.

3. Appropriate low frequency strength and warmth of tone. The concert hall must have strength and impact in the low frequency range to transmit the visceral excitement of the bass drum and tympani, the palpable “thump” of double bass and celli pizzicati, the strength of the tuba. It must also achieve an overall warm tone color for the strings and the other sections.

4. Excellent envelopment and spatial impression. This is a sensation that one is enveloped by the sound, as opposed to just “looking at it”. A listener should feel acoustically close to, and indeed part of, the performance.

5. Appropriate reverberance and liveness for the wide variety of musical uses. A listener’s sense of the sound lingering in the hall has several attributes:

(a) Length of sound decay
(b) Level (loudness) of decay
(c) Level of running reverberance (influences “blend”)
(d) Timbre of decay
(e) Spaciousness/envelopment of decay.

Artec has been studying the relationships between clarity and reverberance for many years, and we have learned that simultaneously achieving a high degree of both clarity and reverberance is possible, and desirable. As with most other acoustical attributes, the most appropriate reverberance is different for different music.

6. Appropriate loudness balance over the frequency spectrum; i.e., the loudness of high, mid, and low frequencies should be in a natural balance. The violin tone should be warm, not scratchy. The brass tone should be warm when desired and brilliant when desired. Both performers and audience want to hear an accurate rendition of the tonal quality of the various instruments and voices. The sound produced by instruments and voices should not be altered by the room; they should sound natural.

7. Excellent balance between the various sections of an orchestra or chorus (or both together). This is basically dependent on the performers and the conductor, but the acoustics of the hall should make it easy for the conductor and players to achieve the desired balance. The musicians must hear each other in an appropriate balance so that they can judge how their sound is carrying to the audience. In many halls the string sound is too weak compared to the brass and percussion.

8. Excellent balance between soloists and ensemble. Much of an audience attends the Performance to hear and see the “star” soloist, so listeners are generally more aware of this specific acoustical concern. The conductor and musicians have a large part to play in achieving excellent balance, but the hall can make it relatively easy or difficult for them.

9. Adequate hearing conditions on stage. Musicians must hear each other well to achieve excellent ensemble. Temporal precision and pitch precision are especially difficult to achieve in a group as large as a symphony orchestra or a large chorus. The hall must provide multiple sound reflections at appropriate times for the musicians to hear each other, but this must be accomplished without stealing too much sound from the audience.

10. Excellent support for each performer’s own sound so that the musician senses that the sound is carrying throughout the hall. This involves particularly the loudness of the sound returning to the performers. When musicians feel the room working with them, they can relax and perform better. Musicians hate halls where they feel that they have to “force” their sound.
The returning sound must not be too late, or it will be perceived as an echo.

A good concert hall should also be free from acoustical deficiencies such as these:

1. Roughness and harshness, stridency, glassiness, edginess, distortion, boominess, and other unnatural or unpleasant coloration.

2. “Dead areas”, where audience or performers have difficulty hearing the sound. These are symptoms of poor distribution of sound energy.

3. Echoes or muddiness, which are caused by long-delayed discrete sound reflections.

4. Noise from heating and cooling systems, lighting equipment or noise originating outside of the auditorium that would distract performers or audience, or be picked up by the microphones.

APPENDIX II: Comparison Data and Plans

Comparison with Other Halls

HALL
SEATS
VOLUME
WIDTH
HEIGHT
LENGTH
T60*
Odessa
1150
14,300m3
21m
17m
40m
2.1 s
Vienna
1600
15,000m3
20m
17.4m
36m
2.5 s
Boston
2625
18,750m3
23m
18.6m
39m
2.2 s

* T60 is calculated for this comparison. The small difference between the calculated and measured T60 for the Odessa Philharmonic Hall is not significant acoustically. Differences between measurements and calculations can be attributed to the dusty condition of the finishes in the hall compared to new finishes, delimitation of the plaster, the assumptions of the Sabine method of calculating reverberation time, and the location(s) where measurements were made.

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Boston Symphony Hall
Scale: 1:200
Main Level

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Musikvereinssaal, Vienna
Scale: 1:200
Main Level

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Philharmonic Hall, Odessa
Scale: 1:200
Main Level