Research proposal

Project: M3-4 Graduation project BPS - Code: 7S545 / 7SS37

Title: The Effect of the Acoustics of a Cinema on the Reproduction of a Movie Soundtrack

Student name: Bart van Lieshout

Student number: 0587232

First faculty supervisor: prof.ir. L.C.J. van Luxemburg

Second faculty supervisor: ir. C.C.J.M. Hak

External supervisor: R.H.C. Wenmaekers MSc.

Introduction

Recordings of music, speech or other sounds have acoustical properties, such as reverberation, definition and clarity. For educational, engineering or entertainment purposes these recordings are often played back through loudspeakers in listening rooms, such as classrooms, recording studios or cinemas. The acoustical properties of a listening room in combination with the used sound system affect the perceived acoustics of the recording (room in room acoustics), which may make an accurate reproduction or demonstration of the recording’s acoustical properties impossible.

In film industry, a lot of money is spent on superb picture and sound quality to give the audience the experience that they are not in the cinema but really in the story. To ensure that this quality is brought to the audience, multiple guidelines are introduced. However, most of the detailed information is about the equipment part of the reproduction, overlooking the importance of acoustical design.

Also, over the years different sound formats existed, with different multichannel possibilities. With nowadays and future modern digital surround sound formats it is important that sounds coming from any particular direction are reproduced without being influenced by cinema acoustics. (older) Cinemas may not met this criterion because of acoustical optimization for Dolby Stereo (or equivalent) which doesn’t heavily rely on the use of the surround channel.

Where the quality of the video reproduction mostly depends on the equipment, for audio reproduction the room acoustics play a very large role.

Contrary to concert hall acoustics, guidelines for cinema acoustics are very limited and not much research on this topic has been done.

The following example illustrates the effect cinema acoustics can have on the sound recording:

When a movie scene is shot outside, the reverberation time is very short. However, when this scene is played back in a cinema with a relative long reverberation time, the original auditory scene is affected. A longer reverberation time is perceived.

This project is an extension of earlier research. Previously, the general effect of acoustics on reproduction quality has been investigated [1], followed by a study on sound control rooms [2].

Research question

What is the effect of  the room acoustics and the sound system on the reproduction of a concerthall and a speech recording in a cinema?

Research objective

The objective is to see if the room acoustics in combination with the audio chain of a cinema influences the audiences perception of the acoustical information of two elements of a movie soundtrack: music and speech.

Relevance of the research

A lot of money and research is spent on superb sound reproduction in cinemas but especially on the equipment part. Good acoustical conditions are mandatory to take full advantage of this surround sound quality in a cinema. The customers wish to be fully emerged in the movie can be taken to a next level due to nowadays digital surround sound formats, good acoustics of the cinema contribute to this experience.

The results of this research possibly can be used to improve acoustical design guidelines of cinemas. They also can be used as information to cinema sound designers to make well-founded decisions about acoustic information on the soundtrack.

Research method

1.         Research formulation

2.         Literature review  - review of literature on acoustical parameters, cinema measurements and other relevant information

3.         Prepare measurements – make contact with cinemas; read up on cinema equipment; set up a logical, smart, fast measurement plan for smooth and professional measurements; perform a test measurement in “de Zwarte Doos”

4.         Perform measurements – perform measurements in cinemas and studios

5.         Reporting results – make a report of all achieved results and discuss them.

Global planning

Start colloquium: BPS Unitday January

Mid-term colloquium: End March, most measurements are done

Final colloquium: End June

Competency development

1.                  Developing a solid measuring method and plan

2.                  Executing this measuring plan in practice, to gain more experience in real measurements

3.                  Gain more knowledge in scientifically acoustical research

Final results

Three main results will be achieved:

The impact of cinema acoustics on the perceived acoustics of a concert hall recording.

The impact of cinema acoustics on the perceived acoustics of a speech recording.

To what acoustical properties are movie sounds restricted to be accurately reproduced.

[1] C.C.J.M. Hak, R.H.C. Wenmaekers, “The effect of Room Acoustics on the Perceived Acoustics of Reproduced Sound”, Internoise 2008, Shanghai, China (2008)

[2]C.C.J.M. Hak, R.H.C. Wenmaekers, “The Impact of Sound Control Room Acoustics on the Perceived Acoustics of a Diffuse Field Recording”, WSEAS TRANSACTIONS on SIGNAL PROCESSING, 4-6, (2010)