Concert Hall Acoustics | A hidden reason some halls are loved & others fail that nobody talks about

Summary

Highlights

• Concert halls like the Concertgebouw Amsterdam are revered for their acoustics, thanks to design choices. 🎻
• Hans Scharoun's Berlin Philharmonie shows vineyard halls can be acoustic marvels too. 🌱
• Sight lines, rather than just width and height, heavily influence hall acoustics. 🔍
• Modern designs often prioritize sight lines, sometimes at the expense of sound quality. 📉
• The challenge for designing new halls is balancing sight lines, sound, and room shape for optimal acoustics. ⚖️

Key Takeaways

• Great acoustics make you feel enveloped in the music and not just an observer. 🎶
• Sight lines play a significant role in acoustics, even more than many architectural shapes. 👀
• Older concert halls achieved better acoustics often due to their design that favored sound over sight. 🏛️
• Modern seating designs can harm acoustics while attempting to improve visual proximity. 💺
• Reverberance is key to a warm, full-bodied sound in a concert hall. 📢

Overview

Chapters

• 00:00 - 01:00: Introduction to Concert Hall Acoustics A great concert hall possesses several key acoustical qualities that enhance the listening experience. These include envelopment, which makes listeners feel as if they are inside the music rather than just observers; clarity, allowing even the innermost voices of the orchestra to be heard; warmth and richness, for a well-balanced and full-bodied sound; and lightness and reverberance to maintain the audibility of room sound during running music.
• 01:00 - 02:30: 19th Century Hall Design The chapter discusses the acoustic qualities that make concert halls great, noting that these qualities are multi-dimensional. It explores why some halls achieve excellent acoustics while others do not, emphasizing that many of the world's greatest concert halls built in the 19th century possess these superior qualities, which modern halls often struggle to surpass. The emphasis is on the room shaping and planning of these historical halls.
• 02:30 - 05:30: Case Study: Concertgebouw vs. Royal Festival Hall The chapter explores the challenges of achieving good acoustics in modern concert halls compared to 19th-century halls, which are still highly regarded. It highlights the difficulty of attaining good acoustics in wide, fan-shaped halls, while also noting that vineyard-style halls, like the Berlin Philharmonie, can have excellent acoustics. Hence, the shape of the plan isn't the sole determinant of acoustic quality. Additionally, the chapter compares two rectangular halls with similar physical features yet differing acoustical results, emphasizing the complexity of acoustical architecture.
• 05:30 - 08:00: Design Mistakes & Lessons Learned The chapter explores a comparison between two famous concert halls: the Concertgebouw in Amsterdam and the Royal Festival Hall in London, focusing on their acoustic qualities. Despite having similar dimensions and shape, the Royal Festival Hall does not achieve the same level of acoustic excellence as the Concertgebouw. The chapter aims to identify the factors contributing to this difference, providing insights into design mistakes and lessons learned in achieving good acoustics.
• 08:00 - 10:30: Modern Hall Design Challenges The chapter titled 'Modern Hall Design Challenges' explores the reasons why the sound quality in various concert halls differs, with a specific focus on the Royal Festival Hall as compared to the Concertgebouw. The key topic of discussion is the impact of sight lines on acoustics, despite the lack of any specific acoustic law relating concert hall shape to sound quality. This chapter promises to delve into how different room designs, from flat floors to various shapes, affect acoustic perception, providing insights into modern hall design challenges.
• 10:30 - 14:30: Sound Projection and Reverberance The chapter 'Sound Projection and Reverberance' discusses the acoustics of different seating arrangements, focusing on the concept of reverberation time, which measures how long sound persists audibly after stopping, expressed in seconds. It distinguishes this from reverberance, which refers to the reverberation audible during ongoing music, occurring shortly (within tenths of a second) after the initial sound in environments such as flat-forward halls.
• 14:30 - 18:00: Reimagining Concert Hall Design The chapter discusses the impact of architectural design on concert hall acoustics. It explains how traditional designs with flat side walls enhance sound reflection, creating a rich reverberant sound that integrates back to the performers. In contrast, steeply-rated concert halls can cause sound to be absorbed by the audience, diminishing the sound's return to the performers. The text delves into the acoustic differences created by various hall structures and how they affect the auditory experience of both performers and audiences.

Concert Hall Acoustics | A hidden reason some halls are loved & others fail that nobody talks about Transcription

• 00:00 - 00:30 a great concert hall will have many acoustical qualities envelopment which makes us feel we are inside the music rather than remote observers on it clarity so the innermost voices of the orchestra can be heard warmth and richness for a well-balanced full-bodied sound lightness and reverberance to give audibility of the roon sound during running music
• 00:30 - 01:00 and reverberation the sustaining of the sound of terminal chords concert hall acoustics is multi-dimensional and a truly great concert hall will achieve highly in each of these qualities why do some concert halls achieve these qualities while others don't many of the world's greatest concert halls were built in the 19th century and few modern halls surpassed these room shaping plan provides one
• 01:00 - 01:30 compelling explanation why the 19th century halls are still revered over modern halls it is impossible to get good acoustics in a wide fan-shaped hall but halls like the berlin philharmonie show vineyard halls can have good acoustics so plan shape is not the only answer if we take two rectangular halls that are similar in many physical respects but have different acoustical outcomes for example
• 01:30 - 02:00 the highly revered concertgebound amsterdam and the more troubled royal festival hall in london by studying the differences between the two halls we may get a pointer towards achieving good acoustics the royal festival hall has a width similar to the concertgebouw it is almost exactly the same height as the concert cabal as the plan shape and basic dimensions of these two halls are so similar why doesn't the royal festival
• 02:00 - 02:30 hall have the same acoustics as the concert cabal why does the sound in the royal festival hall seem to be more remote than it is in the concertgebouw here's the secret it's all about sight lines and that's what we'll cover in the next 10 minutes there is no law of acoustics to explain why the shape of a concert hall in section should have any effect on the acoustics at all this series of rooms from flat floor to
• 02:30 - 03:00 the steepest of seating rakes has the same calculated reverberation time we need to distinguish between reverberation time which relates to sound persisting audibly after terminal chords and is measured in seconds and what we call reverberance which is the reverberation that's audible during running music and occurs in the first few tenths of a second after the arrival of the direct sound in a flat-forward hall such as the
• 03:00 - 03:30 concert cabal performers can project their sound onto the rear wall it is reflected from there and returns to the performers as an integrated part of the room sound or reverberance but in a steeply rated concert hall the same sound is projected into the steep bank of audience seating where it simply dies looking at the cross section the flat parallel side walls of the concertgebouw sustain inter-reflection of sound the sound we
• 03:30 - 04:00 see here finally arriving at the audience after three tenths of a second is a portion of the sound that contributes strongly to the reverberants that the audience hears this flat floored hall has strong reverberance but this steeply raked hall with the same reverberation time would have weak reverberants the acoustical importance of the upper volume of a in a concert hall
• 04:00 - 04:30 has long been underestimated henry lee higginson the great man behind the boston symphony hall in 1900 when observing the existing boston music hall of 1852 wrote to his architect mckim that i've always thought our hall too high just so much space to be filled to no purpose thankfully architect mckim avoided the temptation to fill the empty space at the top of the new boston symphony
• 04:30 - 05:00 hall with audience tears had he chosen to his acoustician sabine would not have had the science to argue against this flaws of modern concert halls are raped to provide good sight lines and this was architect peter morrow's intention when he designed the royal festival hall but he was working on his own at that time there was no such thing as a competent theater consultant
• 05:00 - 05:30 a profession which gradually emerged as theater building started in this country after the war and on which i relied later on and consisted of people who had worked in theaters and knew all about lighting and scene changes and all the rest of it in particularly richard pilbrow of theater projects there was no guidance from mentors because complete generations had had no experience of concert hall
• 05:30 - 06:00 design the very basis of the 19th century concert hall had been swept away by two world wars and an economic depression by 1948 everything had changed from the social mores of audiences and performers to the construction techniques that allowed long span steel trusses wide rooms and deep balcony overhangs as peter morrow observes so i showed round alto and gropius
• 06:00 - 06:30 breuer sarinan you mentioned it uh gideon um kobe say uh frank lloyd never bothered to go to the site he stayed in the office with robert matthew and looked at the section and said have you guys ever designed a concert hall before and then they said no he said it won't work and then he drew a kind of
• 06:30 - 07:00 shape over the section like the shape of a old-fashioned gramophone horn and said that's the shape of a cancer towel absolute nonsense it is interesting to listen to peter morrow on the subject of his next auditorium the nottingham playhouse as his observations apply equally to the royal festival hall there are one or two kind of mistakes the stalls were too steep i wanted really good sight lines
• 07:00 - 07:30 there's nothing worse than looking at some person's shoulder blades instead of the stage so i raked it and that meant that the balcony was pushed up the balcony was rather high up and there was a rather big gap between the stalls audience and the balcony audience which actors found rather distressing because there was this division between the two i think would never do it again
• 07:30 - 08:00 peter morrow had thought that steeply raking the seating rows would automatically provide good sight lines to a low concert platform but as is often the case when architects designed concert halls the seating ranks were chosen merely to link external fire levels together if we bring our current knowledge to analyze the 1948 design we can see the sight line design problem that peter morrow created
• 08:00 - 08:30 and how it could have been avoided so how do we design sight lines draw a line from the point in the stage you want to see the sight point over the head of a seated person and you can work out where the eye position needs to be in the next but one row the assumption is that you look between heads in the row in front of you and over the head of the person in the further row in this example the feet of the cellist are visible to everyone
• 08:30 - 09:00 as the stage height increases the required rate of the stepping is reduced eventually with a high enough stage riser the floor can become flat or even inclined downwards interestingly the stage height at which the flat floor occurs is the same as the concert platform the height in the concertgebouw amsterdam for music performance rather than say dance it's not necessary to see the feet of the performer
• 09:00 - 09:30 if the sight point is set just below the height of a piano keyboard or a cello bow the sight lines for music are acceptable and the required rake of the seating is much less steep when we extend the study to look at all the seating roads on the whole of the main floor of a concert hall we see that the concert platform in the concert cabal is set sufficiently high that all the audience on the main floor can see at least the shoulders of the conductor a typical modern concert hall such as
• 09:30 - 10:00 birmingham symphony hall meets sightline requirements with a much lower stage riser than in the concertgebouw the audience even at the rear of the main floor can see down almost to the feet of the conductor this is achieved by gradually steeping the rake towards the rear despite the steep rake in the royal festival hall when the hall opened the sight lines of the conductor were worse than those in the concert bow when preparing this video
• 10:00 - 10:30 i found it hard to believe the original low content platform was actually ever used but these photos show that when the hall first opened the extremely low stage was used over the years the concert platform has been raised to a height similar to the one in birmingham symphony hall the steep break of the seating in the royal festival hall is damaging to the acoustics but does not even achieve good sight lines however if the designers had flattened
• 10:30 - 11:00 just the front few rows of the main floor the sight lines could have worked with the low platform they intended in this photo so leslie martin has his finger on the exact point where the mistake in the sight lines was made with a flat floored hall it is essential the upstage areas are fairly steeply stepped if the orchestra was on a flat stage as shown in this simulation only the front row of the orchestra would be
• 11:00 - 11:30 visible steeply stepping the upstage of a concert platform makes the full orchestra become visible to the audience on the flat floor and allows musicians to project their sound and hear each other so why have some modern concert halls being built with steep seating breaks the problem that designers are trying to solve is to bring the audience visually close to the performers what acousticians call envelopment
• 11:30 - 12:00 achieves this shortening of distance acoustically and paradoxically is often in the most distant seats in the upper balcony where the sound will seem closest to the listener but visual closeness is a real issue and a highly laudable goal but it generates considerable acoustic challenges as we've discussed all too often bringing the audience closer is achieved by wrapping steeply stepped terraces around the concert platform
• 12:00 - 12:30 so how do designers try to overcome the acoustics challenges the difficulty is the sidewalls disappear and so the only viable lateral side reflections to support clarity must come from balcony fronts or lower angled walls and modeled ceilings to a large extent that can be made to work reasonably well however the price is to be paid in the lack of reverberance and warmth in the room many of the
• 12:30 - 13:00 modern designs exhibit acoustics clarity and sometimes excessive loudness but they do not achieve a warm reverberant sound what if instead of stepping up the terraces immediately more seating rows were added on the flat this is a modern concert hall section you can see the downward sight lines from the audience seating and the upward sight lines that preserve the acoustics of the overhang areas in this modern hall the stage riser is
• 13:00 - 13:30 really quite low unlike the royal festival hall the sight lines have been designed to allow this relatively low stage riser and everyone has good sight lines but if we increase the stage riser from 600 to 1100 while maintaining the sightline criteria we see that the required steepness of the section becomes very much reduced the stage height has increased by 500 millimeters 20 inches
• 13:30 - 14:00 but the last row of seats has reduced in height by 9 meters 30 feet now the sound can reach the rear wall and the upper side walls and create reverberance this would provide an acoustic that supports reverberance while our eyes look towards the orchestra our ears face towards the side walls of the concert hall and this is where the lateral sound which envelops the
• 14:00 - 14:30 audience comes from imagine sitting towards the rear of the main floor we can place an enlarged head there to better see what is happening using traditional geometric acoustics methods we can simulate where the sound arriving at this head is coming from sound that arrives within these cones will be strongly lateral and sound which arise from sufficiently above the heads of the adjacent audience will maintain its strength so sound arriving at our ears
• 14:30 - 15:00 from the areas of the side walls within these trunk truncated cones is critical to achieving good acoustics the first challenge for the concert hall designer then is to get sound onto the sidewall areas we can see that this will happen automatically in a flat floored rectangular concert hall here we see the strong sound in red the weaker sound in yellow and areas receiving no sound because of shadowing in blue we can see that in the concert
• 15:00 - 15:30 capal the listeners ears can see large areas of the sidewall strongly illuminated by the sound source on the concept platform but within the royal festival hall the steep rake of the main floor has reduced the area of the sidewalls and the remaining part is the opposite of flat the audience boxes trap sound and shadow sound so there is little lateral sound in the hall despite the rectangular rim shape
• 15:30 - 16:00 this is a major reason for the poor reverberance in the hall in a modern surround concert hall with its steeply raked main floor we see that projecting side balconies shadow the side wall surfaces what little surface remains cannot reflect sound to the opposite wall to generate reverberance so now we understand a little more about why the 19th century concert hall works should a modern concert hall
• 16:00 - 16:30 return to that model no to start with the sight lines from a flat floor are not good enough but halls with a low rake like symphony hall birmingham show that excellent sight lines can be achieved without steeply raking the floor if designers avoid steep seating rakes and placing audience tears up in the gods there is a chance for the sound to bloom in the unoccupied upper volume of a
• 16:30 - 17:00 concert hall the upper volume of the hole is where that wonderful quality of reverberance is developed and this can't coexist with the acoustic absorption caused by audience seating we've seen that good sight lines or bad sight lines can be independent of the steepness of the seating rake but to provide the strong reverberance that's so desirable in concert halls seating rakes and ceiling heights must
• 17:00 - 17:30 be designed so there is plenty of empty space at the top of the concert hall will this allow us to have our cake audience wrap and eat it clarity warmth envelopment reverberance all in one room we think so but to achieve this requires a rethink of concert hall design with a new model emerging we have lots of ideas on how this will look but that's a video for another day
• 17:30 - 18:00 you