This is the era of multi-screen movie halls that are usually integrated with shopping malls and other commercial spaces. While this need is becoming more realistic and practical by the day, it incidentally throws up a number of acoustic and at times vibration related challenges both within the enclosed space and as well to its boundaries.
Theatre Acoustics is the subject of discussion for this post; what contributes to the true composition of an appropriately treated audio listening space consists of many considerations, some of the key parameters are:
- Effective volume space and dimensions of the hall.
- Standing waves and first incidence locations, dead zones.
- Type of wall partitions, surfaces and their treatments, STC ratings
- Type of audio system to be used, their specifications, locations of the output devices and mounting.
- Frequency responses of the sound field, RT, SI and Articulation Index.
- Locations of door/s access ways and connections to common corridors.
Sound, by all its prospect is a subjective auditory response of its user; since the appreciation of its content involves a number of phyco-acoustic matrix, designing an all inclusive ideal listening space is a challenge of sorts and requires meticulous plan, design and its execution.
Most theatre spaces need to possess recognition of spoken dialogues more correctly, these have a broad range of frequencies between 200Hz to around 6000Hz depending on the gender, age and mixing of voices; this band of frequencies are also categorised under Articulation Index that defines the recognition of voice and speech.
Typical speaker layout in a movie theatre
Next, the lower order frequencies are the real mess. The large woofers and associated amplifiers pump out considerable bass energies into a nearly sealed volume space. The lower the frequency induced, the higher the challenge is; right from standing waves to cavity resonances, from noise leakages to structural vibrations, all creep into the overall performance of the listening space.
The propriety of realising good theatre acoustics begins at the construction stage of the space; civil and structural elements play a key role in determining the basic acoustic characteristics of the upcoming listening space. The locations of entry and exit doors and other vents needs to be modelled using qualified acoustic simulation tools and optimised to check propagation and leakages through this vulnerable area.
Complex electronic system components of theatre acoustic
Acoustic liner materials and their tested / declared values are to be carefully scrutinised based on the overall sound energy being generated and further considering the frequencies within the closed space. First incidence spots are to be properly assessed to treat for bounce backs and direct reflections. Skilled installation procedures are as important as the material itself to realise the outcome in totality.
Iterative trials are mandatory to validate the effective acoustic performance of the considered space. Pure tones and random noise sources are used for calibrating the full spectrum response of the space that leads to refinements and fine tuning of all the components involved in making the theatre acoustics, perform.
Theatre Acoustic energy districution modelling
Fancy sound systems with hyper specifications and a great number of speaker configurations call themselves as the in-thing without substantiating their technical validity; even the kinds of Dolby, DTS, Atmos and many such advanced systems fail to deliver the immersive audio experience crippled by the poor design and overall build of the physical listening enclosure.
We have an array of experience addressing a variety of non-performing theatre spaces; at times, the human dialogues are not heard, in other cases, overwhelming bass saturates the space causing deafening effects. Leakages through the doors to the connecting corridors and sometimes to the adjoining theatre spaces are also observed. There are cases of structural floor vibrations caused by resonances that have caused significant damage to the adjoining spaces and their occupancies.
NV Dynamics practices the holistic approach of going through the theatre acoustics requirements. We believe in creating sound reproduction spaces as an outcome of meticulous design and its execution. Our long-time experience of working on engineering noise consulting services is furthering the overall understanding of theatre acoustics in a better way.