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Deep balconies can enhance a room's acoustics by improving sound distribution.
Deep balconies can enhance a room's acoustics by improving sound distribution.
False
An acoustical shadow usually forms under a wide balcony.
An acoustical shadow usually forms under a wide balcony.
True
A room loses reverberance because sound that goes under a deep balcony returns with enough energy.
A room loses reverberance because sound that goes under a deep balcony returns with enough energy.
False
The ceiling height in a concert hall is often the variable that controls room volume.
The ceiling height in a concert hall is often the variable that controls room volume.
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The absorption profile of the under-balcony volume is similar to that of a closed window.
The absorption profile of the under-balcony volume is similar to that of a closed window.
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As audience size increases, the sound strength also increases in music performance spaces.
As audience size increases, the sound strength also increases in music performance spaces.
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Acoustical warmth is achieved by increasing the high-frequency content of a room.
Acoustical warmth is achieved by increasing the high-frequency content of a room.
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A concert hall with 1800 seats and a 2.4-second unoccupied reverberation time typically requires a room volume of 815,000 cubic yards.
A concert hall with 1800 seats and a 2.4-second unoccupied reverberation time typically requires a room volume of 815,000 cubic yards.
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Gypsum board, owing to its composition, absorbs low-frequency sound effectively.
Gypsum board, owing to its composition, absorbs low-frequency sound effectively.
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Chamber music rooms are generally less loud, with G values from $9.0$ to $13.0$ decibels.
Chamber music rooms are generally less loud, with G values from $9.0$ to $13.0$ decibels.
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Rooms with excessive low-frequency energy are described as being acoustically 'bright'.
Rooms with excessive low-frequency energy are described as being acoustically 'bright'.
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Opera halls are known to be more reverberant with unoccupied RT values of $1.5$ to $1.9$ seconds.
Opera halls are known to be more reverberant with unoccupied RT values of $1.5$ to $1.9$ seconds.
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Designing a room with brick surfaces can help to achieve warmth.
Designing a room with brick surfaces can help to achieve warmth.
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Balconies are used to relocate seats away from the source of the sound.
Balconies are used to relocate seats away from the source of the sound.
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Balconies, when protruding from the rear wall, can create stronger echoes.
Balconies, when protruding from the rear wall, can create stronger echoes.
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Side balconies redirect sounds to the ceiling which leads to an increase in loudness.
Side balconies redirect sounds to the ceiling which leads to an increase in loudness.
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To minimize room absorption, use massive building materials with high sound absorption coefficients.
To minimize room absorption, use massive building materials with high sound absorption coefficients.
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The audience plane in a concert hall provides less than 50% of the total sound absorption.
The audience plane in a concert hall provides less than 50% of the total sound absorption.
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To promote loudness for the audience, you need to increase the absorption of the audience itself.
To promote loudness for the audience, you need to increase the absorption of the audience itself.
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The absorption by the audience is a function of the number of seats, rather than the area of the audience plane.
The absorption by the audience is a function of the number of seats, rather than the area of the audience plane.
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A denser, more compact audience with smaller mean distances between seats translates to less absorption for a given room occupancy.
A denser, more compact audience with smaller mean distances between seats translates to less absorption for a given room occupancy.
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A configuration with more and smaller audience blocks absorbs less than one with fewer and larger blocks.
A configuration with more and smaller audience blocks absorbs less than one with fewer and larger blocks.
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The total effective absorbing area of an audience with a maximal number of blocks approaches 1.4 times the total audience area as measured in plan.
The total effective absorbing area of an audience with a maximal number of blocks approaches 1.4 times the total audience area as measured in plan.
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With a shallow raked audience plane, less sound will be absorbed.
With a shallow raked audience plane, less sound will be absorbed.
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Wood in concert halls should be secured to stiff, massive materials with minimized air pockets behind and using a stiff adhesive so the panel and substrate act as one element.
Wood in concert halls should be secured to stiff, massive materials with minimized air pockets behind and using a stiff adhesive so the panel and substrate act as one element.
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Long wavelengths reflect off small surfaces, therefore large surfaces do not contribute to promoting warmth in an auditorium.
Long wavelengths reflect off small surfaces, therefore large surfaces do not contribute to promoting warmth in an auditorium.
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Small surfaces with angles similar to adjacent surfaces can appear as one single surface to short sound wavelengths.
Small surfaces with angles similar to adjacent surfaces can appear as one single surface to short sound wavelengths.
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The bass index is calculated by taking the sound strength at 125 Hz and subtracting the average of the sound strength at 250 Hz and 1000 Hz.
The bass index is calculated by taking the sound strength at 125 Hz and subtracting the average of the sound strength at 250 Hz and 1000 Hz.
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Rooms with a lower bass index will likely have a higher low-frequency loudness.
Rooms with a lower bass index will likely have a higher low-frequency loudness.
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Rooms used for unamplified music will need low frequency support which would likely cause amplified music to sound less boomy.
Rooms used for unamplified music will need low frequency support which would likely cause amplified music to sound less boomy.
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Binaural response is the sense that sound arrives from a single point, usually the center, based on our bodies symmetrical nature.
Binaural response is the sense that sound arrives from a single point, usually the center, based on our bodies symmetrical nature.
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Lateral reflections from the ceiling trigger a binaural response, giving the listener a sense that they are immersed in sound.
Lateral reflections from the ceiling trigger a binaural response, giving the listener a sense that they are immersed in sound.
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The lateral fraction (LF) method uses a unidirectional microphone to measure sound from only one direction.
The lateral fraction (LF) method uses a unidirectional microphone to measure sound from only one direction.
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The Binaural Quality Index (BQI) uses a model head with microphones placed in anatomically correct ears.
The Binaural Quality Index (BQI) uses a model head with microphones placed in anatomically correct ears.
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The BQI averages the 100-Hz, 1,000-Hz, and 10,000-Hz octave bands.
The BQI averages the 100-Hz, 1,000-Hz, and 10,000-Hz octave bands.
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The early lateral fraction typically ranges from 0.05 to 0.50.
The early lateral fraction typically ranges from 0.05 to 0.50.
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Target LF values range from a minimum of 0.20 to a maximum of 0.45.
Target LF values range from a minimum of 0.20 to a maximum of 0.45.
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Higher LF values always guarantee optimal sound quality in all cases.
Higher LF values always guarantee optimal sound quality in all cases.
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The most-admired concert halls measure BQI values of around 0.65, while the least-admired halls average 0.45.
The most-admired concert halls measure BQI values of around 0.65, while the least-admired halls average 0.45.
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The just-noticeable difference measured when subjects judge BQI values is approximately 0.165.
The just-noticeable difference measured when subjects judge BQI values is approximately 0.165.
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Early lateral reflections arriving within 80 milliseconds of the direct sound contribute to listener envelopment.
Early lateral reflections arriving within 80 milliseconds of the direct sound contribute to listener envelopment.
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The lateral fraction measured after 80 milliseconds is used to quantify apparent source width.
The lateral fraction measured after 80 milliseconds is used to quantify apparent source width.
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Before 1960, it was generally believed that early sound was the most important factor for spatial impression.
Before 1960, it was generally believed that early sound was the most important factor for spatial impression.
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A large apparent source width gives listeners the sense that they and the orchestra occupy distinct spaces.
A large apparent source width gives listeners the sense that they and the orchestra occupy distinct spaces.
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Late lateral loudness (GLL) has little influence on listener envelopment.
Late lateral loudness (GLL) has little influence on listener envelopment.
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A room with a large audience area will likely enjoy high levels of listener envelopment.
A room with a large audience area will likely enjoy high levels of listener envelopment.
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The sense of acoustic intimacy is only a function of the reverberation level of a space.
The sense of acoustic intimacy is only a function of the reverberation level of a space.
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Bringing earlier early reflections can make a big room sound smaller and more intimate.
Bringing earlier early reflections can make a big room sound smaller and more intimate.
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Study Notes
Room Acoustics Qualities - Loudness
- Concertgoers desire equal sound energy distribution across an auditorium, but sound levels vary greatly depending on the venue.
- Halls with fewer than 1,000 seats may experience excessive loudness, contrary to most larger halls, which aim for increased sound energy per seat.
- Halls with more perceived loudness often exhibit less sound absorption, more early reflections, and shorter distances between stage and seating.
Room Acoustics Qualities - Loudness (Formula for reflected sound pressure level)
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The sound pressure level resulting from reflections can be estimated using this formula: Lp reflected = Lw sound power + 10·log (4/ (room constant * RT * 0.174r))
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Where:
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Lp is the sound pressure level from room reflections
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Lw is the source sound power level of the orchestra
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A is the total absorption in metric sabins (sq. meters times absorption coefficient).
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r is the distance from the source to the receiver in meters
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RT is the reverberation time
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The sound pressure level is influenced by orchestra volume, room reflectivity, reverberation time, and proximity to the orchestra.
Room Acoustics Qualities - Loudness (Measuring Sound Strength)
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Acoustic quality "loudness" is measured by sound energy at a listener position in comparison to the same sound source at ten meters in an open space.
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The value is represented as G with a + or - decibel (dB) indicator.
Room Acoustics Qualities - Loudness (Minimizing Room Absorption)
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Minimize massive building materials with low sound coefficients.
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Minimize sound-absorbing surfaces (such as curtains).
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Minimize the total area of surfaces exposed to sound.
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The audience plane accounts for between 50-90% of total sound absorption.
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Seat construction and upholstery material impact sound absorption significantly.
Room Acoustics Qualities - Loudness (Absorption by Audience)
- Sound absorption by the audience depends on the surface area of the audience plane, not just the number of seats.
- Denser, more compact seating configurations lead to less audience absorption for a given seating capacity.
- Audiences with shorter distances between seats affect overall absorption levels.
- Audience configuration's shape impacts sound absorption.
Room Acoustics Qualities - Geometry of the Volume
- Steeply raked audience planes result in better sound absorption due to sound waves better approximating a plane perpendicular to their path.
- Flatter audience planes facilitate sound reflection off various room surfaces.
Room Acoustics Qualities - Geometry (Optimizing Loudness)
- Reduce the distance between the source and receiver positions of seats.
- Minimize total surface area of room surfaces.
- Maximize early direct sound arrival.
Room Acoustics Qualities - Loudness (Balconies)
- Balconies relocate seats, bringing them closer to the music source.
- They disrupt rear walls, diminishing echo potential.
- Balconies redirect sound downwards, improving perceived volume.
- Balconies are less effective and can be damaging if they create a large overhang, leading to an acoustical shadow.
Room Acoustics Qualities - Geometry (Balconies and Loudness)
- Large balcony overhangs produce an acoustical shadow, reducing sound reflected through this space.
- Shallow balconies allow for overhead reflection, improving perceived loudness.
Room Acoustics Qualities - Spatial Impression (Binaural Qualities)
- People experience sound differently depending on the sound's direction of origin.
- Sidewall reflections trigger binaural response (the perception of sound arriving from surrounding directions).
- Spatial impression is heavily affected by the room geometry, especially the position and angle of sound reflecting surfaces.
Room Acoustics Qualities - Spatial Impression (Methods)
- Lateral fraction (LF) evaluates the percentage of sound arriving from the sides.
- It is a ratio of the sum of sound levels from two opposite directions, to the overall sum from all directions.
- BQI (Binaural Quality Index) calculates correlation between sound level at both ears, using a model head.
- The higher the proportion of side-arriving sound to total sound heard, the stronger the sense of spatial impression
Room Acoustics Qualities - Spatial Impression (Calculating BQI and LF)
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LF metric is calculated by measuring sound at 125 Hz, 250Hz, 500Hz and 1000 Hz
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BQI averages for 500Hz, 1000 Hz, and 2000 Hz
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Higher values are interpreted as a strong sense of spatial impression
Room Acoustics Qualities - Intimacy
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Big rooms typically sound larger than smaller rooms.
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The time between the direct sound and its first reflection (ITDG) influences the perceived sound intimacy.
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Shorter ITDG values signify more intimate listening environments.
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Fan shaped rooms tend to create less of a sense of intimacy than rectangular rooms.
Room Acoustics Qualities - Warmth
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Listeners prefer low frequency sound when listening to un-amplified music (robust low-frequency content).
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Wall and ceiling panel configurations act as sound absorbers and impact the low-frequency response.
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Rooms lacking adequate low-frequency reverberation feel un-warm.
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Rooms with excessive low-frequency energy sound "dark".
Room Acoustics Qualities - Warmth (Bass Index)
- Warmth is evaluated using the bass index.
- The bass index compares the G value at 125Hz (G125), to the average G value at 500Hz, and 1000 Hz (Gmid).
- Higher bass indices suggest warmer rooms.
Room Acoustics Qualities - Warmth (Materials Selection)
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To achieve warmth in a space, consider more massive and solid material in construction
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Lightweight materials generally absorb more low frequencies.
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Gypsum board absorbs low frequency sounds much more effectively than concrete or masonry.
Room Acoustics Qualities - Concert Hall Types (Geometry)
- Shoebox-shaped halls are good for promoting lateral reflections while providing a sense of a broad sound.
- Fan-shaped halls help sound arrive closer from the stage.
- Surround (Terraced halls) help create a sense of intimacy.
- Reverse-fan shaped halls also enhance sound reaching the audience by directing reflecting off side walls.
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Description
Explore the fascinating world of acoustics in concert halls and performance spaces. This quiz covers concepts such as sound distribution, reverberation, and the impact of room geometry on acoustical properties. Test your understanding of how various factors influence sound quality in music venues.
