Auditorium Types: 6 Main Types of Auditorium

Type # 1. Lecture Halls:

There are many sizes of lecture halls. Large lecture halls can be treated as theatres in terms of acoustics. This could lead to the same problems with acoustic design as in Table 3. A lecture hall with a good acoustic design may not require sound amplification until it is larger than 1,400m 3 or can accommodate more than 500 people.

The best way to calculate the reverberation times in all cases is to assume a 2/3 audience attendance.

Modern lecture halls are designed to exclude external noise. This means that natural light and ventilation are not included. This means that ceiling units with the required, artificial lighting and noise suppression in ventilation and air-conditioning systems can be a top priority.

A budding may include smaller lecture halls (e.g., classrooms in schools or colleges). These rooms will need special attention to avoid external noises from adjacent rooms. Particular consideration should be given to noise transmissions from nearby rooms.

Halls intended to deliver both speech or music do not usually present any problems unless the hall’s volume exceeds 3,000 m.

Reverberation times can be used to compromise the requirements of speech and music. For example, it could be between 1 and 2 seconds and still provide acceptable listening with either speech or music in smaller halls.

The hall’s reverberation rate should be less than 1 second if it is used for speech only. A reverberation period that is close to or slightly more than 2 seconds is ideal for musical performances.

However, it is important to remember that music and speech are not guaranteed to be perfect if there is a compromise in reverberation.

Type #2 Classrooms:

Classrooms present no acoustical problems other than those relating to sound insulation. This can be analyzed in terms of adjacency and occupancy. Table 4 shows the classification of school rooms based on their occupancy.

“adjacency refers to the minimum noise reduction required between rooms belonging to different categories as listed in Table 4. Table 5 shows the minimum noise reduction required between different school rooms (as indicated in Table 4), as British standards recommended.

A room that has two uses must be classified according to the most severe. At times, a Category C room could be used for Category B duties but would still be classified as a Category D room.

Schools and colleges have classroom volumes ranging between 225 to 350 m 3 and corresponding floor areas of 50 to 100m 2. Acoustic treatment is rarely necessary for classrooms with such dimensions to ensure optimal reverberation times between 0.6 and 0.9 seconds when full.

Type # 3. Theatres:

Theaters require high levels of intelligibility, sound volume, and speech quality that allow the audience to understand the subtle or dramatic effects of the actors.

Theatres pose the most challenging acoustic design problems due to these requirements. These problems are further complicated by large audiences and the relation between the performance area and the audience.

These are the problems that theatre acoustics can face:

(a) Provide ample and powerful, short-delayed reflections for every area of the audience.

(b) Ensure even sound distribution throughout the theatre

(c) Raising sound source and raking audience area

(d) Short-delayed reflections on the performing areas

(e) Reverberation time and frequency characteristics are ideal for performances other than stage plays.

(f) To eliminate echoes, delayed reflections and sound concentrations in the often-used circular theatre form without creating an excessively-dead acoustical atmosphere.

(g) Locating seats in theatre so sufficient sound waves (especially high-frequency speech components) reach spectators behind the performer.

(h) A sufficiency large, easily removable shell on the acting area with variable capacity;

(i) Installing a discreet, high-quality sound amplifier system for audiences with a capacity greater than 1,500.

Type # 4. Auditoria for music:

Music quality is often rated subjectively. Mechanical analysis cannot produce a correlation between objective measurements and subjective responses. Although mechanical analysis can indicate the mathematical form of complex sounds, it cannot accurately and completely express individual appreciation.

Many factors influence the “quality music. So many of these factors can have an impact on the composition or performance of the music.

Acoustics and musical style are closely related. This means that both the composition and the design of an auditorium may be affected. In practice, this means that an optimum acoustical setting is required for any particular musical composition or rendering. The same applies to acoustic environments. Therefore, auditorium design may need to be flexible to accommodate different types of performances.

Table 6 summarizes musical factors (those that affect the subjective response to music) and the associated acoustic parameters. This table is only a guideline for the auditoria’s acoustic design.

This table does NOT include non-acoustical elements (e.g., aesthetic, financial, and other requirements), which could also play a role in an individual’s enjoyment of music. Table 7 summarizes the basic shapes of the auditoria and some of their most important acoustic characteristics.

Reverberation time is a traditional parameter in auditoria design. However, this must be balanced as the auditorium was designed to support a particular type of musical performance.

The optimal reverberation period for music is independent of the auditorium’s volume, unlike that for speech. However, it is dependent on the type of music. Table 8 shows the optimal reverberation time for different types of music. It is based on subjective analysis.

Reverberation time can be easily determined, although it is an objective parameter. Even though measured reverberation time in auditoria can differ from design estimates, these differences can be corrected or eliminated by additional acoustic treatment.

The quality of music can be directly affected by the control of reverberation time. Table 9 lists the various factors that affect the quality of music in an auditorium. Table 9 shows the requirements for good quality music. These are listed in Table 10.

Surface treatment can control sound diffusion. Surface treatment can control the diffusion of sound by removing projections and creating irregularities.

To be effective, projections and surface irregularities must be large (about one-seventh wavelength). Alternate treatments (to diffuse sound) include random or alternate applications of reflective and absorptive treatments and the elimination of any degree of parallelism.

Type # 5. Concert Halls and Opera Houses:

There are different requirements for opera houses and concert halls than for other types. A lower reverberation time is required to improve the intimacy and definition of sound in concert halls or opera houses.

The type of opera performed will also affect the theatre’s reverberation times and shape. Operas that require more depth of tone, for example, will benefit from longer reverberation times.

Another difference is in the size and volume of the auditoria, as illustrated in Table 11. Table 11 shows that the optimal volume per seat for the auditoria used to deliver a speech is 2-8m 3.

Type # 6. Studios:

Studio equipment used to pick up microphones has its requirements.

These require particular attention:

(a) Optimum size;

(b) Optimum shape;

(c) Optimum reverberation characteristics;

(d) High degree difference;

(e) Low background noise

The BBC (British Broadcasting Corporation), minimum volume requirements for music studios are good sources of information. It can be found in Table 12.

The minimum studio volume does not necessarily correspond to the number of performers. For example, the minimum studio volume for four performers is 10.6m 3. This rises to 48.2m 3 for performers when there are 128 performers.

Studio volume requirements can also be expressed in simple ratios between the room’s height and width, and length. This is shown in Table 13. The width and length ratios of studios with low ceilings should be adjusted to 2.50 or 3.20.

However, if the studio is too long relative to its width, then the desired ratios are 1.25 or 3.20 for width and length.

The distance between the microphone and the source of sound and the acoustic characteristics in the studio can affect the optimal reverberation characteristics. Variable absorption and screening treatment can be used to adjust the latter.

 

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