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Noise exposure in movie theaters: a preliminary study of sound levels during the showing of 25 films.

Abstract

The harmful effects of noise exposure during leisure-time activities are beginning to receive some scrutiny. We conducted a preliminary study to investigate the noise levels during the showings of 25 different films. During each screening, various sound measurements were made with a dosimeter. The movies were classified on the basis of both their Motion Picture Association of America (MPAA) rating and their genre, and the size of the theater and the size of the audience were taken into consideration in the final analysis. Our findings suggest that the sound levels of many movies might be harmful to hearing, although we can draw no definitive conclusions. We did not discern any relationship between noise levels and either MPAA rating or genre. Further studies are recommended.

Introduction

Noise exposure associated with the workplace has been linked to hearing loss for many years. In response, the United States government's Occupational Safety and Health Administration (OSHA) issued regulations to limit occupational exposure to noise. Attention is now being directed to the effects of noise exposure during leisure-time activities. Various studies have shown that sound levels at concerts and nightclubs and those emitted by personal listening devices can be hazardous. (1-3) Also, seemingly innocuous hazards may be more ubiquitous than previously thought; for example, entertainment options for children such as toys and arcade games have been found to emit potentially harmful levels of noise. (4,5)

With the exception of a preliminary study reported by the senior author (R.T.S.) and colleagues in 1998, (6) no investigation of the sound levels in movie theaters has been conducted. In view of recent technological advances in sound effects, the question of whether movie theater noise reaches hazardous levels warrants reexamination. In this article, we describe another preliminary study of this subject.

Materials and methods

For this study, 25 movies were randomly selected for viewing. Over a period of 1 month, one of the authors (A.W.) watched each of these movies in a multiplex that housed a number of theaters of the same size and design. During the showings, noise levels were measured with a Quest NoisePro DLX noise logging dosimeter (Coll Health and Safety; Mississaugua, Ont.). All measurements were made with A-weighting (dBA), slow averaging, and a 5-dB exchange rate. Five different sound measurements were made:

* the maximum sound level for each film;

* the peak level (Lpk)--that is, the highest instantaneous sound level that the microphone detected;

* a dose reading where a value of 100% is the maximum allowable exposure to accumulated continuous noise (according to OSHA, a 100% dose occurs for an average sound level of 90 dBA over an 8-hour period);

* the average sound level (Lavg);

* the sound exposure level (SEL); assuming the sampled run time to be greater than 1 second, the SEL is the equivalent 1-second noise that would be equal in energy to the noise that was sampled over the test period.

The manufacturer of the dosimeter cautions that the Lpk reading is independent of the slow/fast response for which the unit is set, so it should be read with caution because the machinery's wiring can greatly increase the levels of the most quiet of sounds. The data were analyzed by QuestSuite Professional II software (Quest Technologies; Oconomowoc, Wis.).

The movies were classified on the basis of both their Motion Picture Association of America (MPAA) rating and their genre (table 1). The size of each individual movie theater and the size of the audience during each screening were also measured to ensure that the acoustic environments were similar when viewing films of different ratings and genres.

Our study's primary aim was to determine whether a movie-goer is exposed to noise levels that could be harmful to hearing. A secondary goal was to determine whether a specific MPAA rating or genre is predictive of sound levels.

Results

There were no significant differences in the size, shape, and capacity of the individual theaters, and during the screenings, there were no significant differences in audience size.

Sound levels. The three highest maximum sound levels were recorded during the showings of Transformers (133.9 dBA), License to Wed (129.1 dBA), and The Simpsons Movie (128.6 dBA). The lowest levels were recorded during Evening (105.4 dBA), You Kill Me (109.0 dBA), and I Know Who Killed Me (109.4 dBA) (table 2).

The highest Lavg readings were recorded during Rush Hour 3 (80.2 dBA), Who's Your Caddy? (78.3 dBA), and Hairspray (78.3 dBA). The lowest levels were recorded during Evening, You Kill Me, and No Reservations--52.0, 52.1, and 55.9 dBA, respectively (table 2). The most prominent differences between these two groups of movies were that the latter featured much more conversation and the few high-intensity noises that did occur were of short duration. The high-Lavg films featured near-constant background music.

Overall SEL readings were highest for Hairspray, Rush Hour 3, and Transformers, with levels of 142.4,142.1, and 141.5 dBA, respectively (table 2). Of these three films, only Hairspray was a surprising finding; its place at the top of this list was probably attributable to the presence of nearly continuous background music.

The two movies with the least amount of time during which SEL readings reached or exceeded 90 dBA were You Kill Me (13 min cumulative) and Evening (20 min). Neither motion picture ever registered a noise level of 110 dBA, and even levels at or above 100 dbA were fairly scarce--2 minutes for You Kill Me and 7.5 seconds for Evening (table 3).

MPAA rating. Of the 25 films, 15 were rated PG- 13, 5 were rated R, 4 were rated PG, and 1 was rated G (table 1). The relative paucity of G, PG, and R movies in this study made it difficult to make valid comparisons on the basis of MPAA rating, so these data should be interpreted with caution. But overall, we did not find any association between rating and sound level.

The mean SEL was 131.5 dBA for the G/PG films, 131.8 dBA for the PG- 13 films, and 126.6 dBA for the R-rated films. The SELs of the 5 G/PG movies (Becoming lane, Hairspray, No Reservations, Ratatouille, and Underdog) raise concerns about the sound levels in movies geared toward families and children, and we believe that this warrants further investigation.

We found a somewhat similar trend when we determined mean Lavg levels according to MPAA rating: 68.1 dBA for the G/PG films, 69.6 dBA for the PG-13 films, and 62.9 dBA for the R films.

Genre. Our data show that a film's genre was not predictive of noise levels. Of course, it is plausible that sound levels for a specific film would vary across different movie theaters. Confounding factors might include the age of the theater and the type, quality, and size of the sound equipment, as well as other factors.

Discussion

It is important to identify which recreational activities pose a hearing hazard so that we can determine their relative importance and raise public awareness of them. Chung et al reported a troubling survey finding that a majority of adolescents and young adults had experienced impaired hearing or tinnitus after exposure to loud music at concerts or in clubs. (7) Unfortunately, only a few of them (8%) considered hearing loss to be a significant problem. Fortunately, most of the respondents said that they would be motivated to use ear protection if they were aware of the potential for permanent hearing loss (66% of respondents) or if such protection were advised by a medical professional (59%). Another survey found that an informational campaign that highlighted the risks associated with loud music could change young people's attitudes about noise. (8)

The movie theater is one of the most popular entertainment venues for families. Movie-goers obviously feel that the overall experience of watching a motion picture in a theater is worth the cost. Many would argue that the acoustics and sound effects are an important part of that experience; the sound effects of movies seen in theaters are difficult to replicate at home.

It has been suggested that children and adults should not be exposed at all to levels of 120 and 140 dB, respectively. Although these limits are controversial and have not been confirmed by any incontrovertible evidence, they can be used as reasonable guidelines. And our data certainly show that children who attend movies are likely to be exposed to levels well above 120 dB. Transformers, a film geared toward a younger audience, was the movie in which sound levels exceeded 90 dBA for the longest amount of time (126 min), and it was the only movie in which the maximum level exceeded 130 dBA.

Based on our analysis of exposure times and sound levels, it appears conceivable that movie-going might contribute to hearing loss, depending on the frequency and duration of exposures. For example, OSHA recommends that exposure to 115 dBA be limited to no more than 15 minutes. While no such degree of exposure occurred in this study, maximum sound levels reached or exceeded 110 dBA in 22 of the 25 movies we studied.

If it can be confirmed that movies do indeed pose a hearing hazard, changes are called for, and education and the promotion of precautions similar to those considered for rock concerts and other noisy activities may be appropriate. Changes in movie industry sound practices might also be appropriate.

This study was not designed to prove whether exposure to movie noise is either damaging or safe. Rather, it was a preliminary study to determine whether noise exposure is of sufficient magnitude to suggest a need for further investigation. We believe that it is, and we believe that prospective studies that include audiometry are warranted in order to more accurately identify the role of these sound exposures in either temporary or permanent changes in hearing thresholds.

References

(1.) Cohen A, Anticaglia J, Jones H. Sociocusis--hearing loss from non" occupational noise exposure. Sound &Vibration 1970;4(11):12-20.

(2.) Clark WW. Noise exposure from leisure activities: A review. J Acoust Soc Am 1991;90(1):175-81.

(3.) Mostafapour SP, Lahargoue K, Gates GA. Noise-induced hearing loss in young adults: The role of personal listening devices and other sources of leisure noise. Laryngoscope 1998;108(12):1832-9.

(4.) Yaremchuk K, Dickson L, Burk K, Shivapuja BG. Noise level analysis of commercially available toys. Int J Pediatr Otorhinolaryngol 1997; 41(2):187-97.

(5.) Plakke BL. Noise levels of electronic arcade games: A potential hearing hazard to children. Ear Hear 1983;4(4):202-3.

(6.) Sataloff RT, Rau G, Preston L. Noise exposure in movie theaters. Journal of Occupational Hearing Loss 1998;1(4):281-2.

(7.) Chung JH, Des Roches CM, Meunier J, Eavey RD. Evaluation of noise-induced hearing loss in young people using a web-based survey technique. Pediatrics 2005; 115 (4) :861-7.

(8.) Widen SE, Holmes AE, Erlandsson SI. Reported hearing protection use in young adults from Sweden and the USA: Effects of attitude and gender. Intl J Audiol 2006;45(5):273-80.

Anna Warszawa, MD; Robert T. Sataloff, MD, DMA, FACS

From the Department of Otolaryngology-Head and Neck Surgery, Drexel University College of Medicine, Philadelphia.

Corresponding author: Robert T. Sataloff, MD, DMA, Department of Otolaryngology-Head and Neck Surgery, Drexel University College of Medicine, 1721 Pine St., Philadelphia, PA 19103. E-mail: RTSataloff@PhillyENT.com
Table 1. MPAA * rating and genre for the 25 films studied

                         MPAA
Title                    rating   Genre

Becoming Jane            PG       Biography, drama, romance
El Cantante              R        Biography, musical, drama
Evening                  PG-13    Drama
Hairspray                PG       Musical, drama, comedy
Harry Potter and         PG-13    Family, drama, fantasy, adventure
  the Order of the
  Phoenix

Hot Rod                  PG-13    Action, adventure, teen drama
I Know Who Killed Me     R        Drama, thriller
I Now Pronounce You      PG-13    Comedy
  Chuck and Larry
Knocked Up               R        Comedy, romance, drama
Last Legion              PG-13    Action, adventure, war drama

License to Wed           PG-13    Comedy, romance
Live Free or Die Hard    PG-13    Action, adventure, thriller, crime
No Reservations          PG       Comedy, romance, drama
Ratatouille              G        Animated family comedy
Rescue Dawn              PG-13    Action, adventure, war drama

Rush Hour 3              PG-13    Action, adventure, comedy
Skinwalkers              PG-13    Action, adventure, horror,
                                    suspense thriller
Stardust                 PG-13    Adventure, sci-fi thriller,
                                    fantasy, drama
Sunshine                 R        Adventure, sci-fi mystery, crime
The Bourne               PG-13    Action, adventure, mystery
  Ultimatum                         thriller, drama,
                                    suspense

The Simpsons Movie       PG-13    Animated comedy
Transformers             PG-13    Action, adventure, sci-fi thriller
Underdog                 PG       Action, adventure, sci-fi,
                                    family comedy
Who's Your Caddy?        PG-13    Sports comedy
You Kill Me              R        Comedy, thriller, crime

* MPAA = Motion Picture Association of America.

Table 2. Measured sound levels

                         Max      Lpk      Dose     Lavg     SEL
Title                   (dBA)    (dBA)     (%)     (dBA)    (dBA)

Becoming Jane            127.7    139.2    0.578     63.0    126.8
El Cantante              115.1    117.2    3.716     76.0    140.3
Evening                  105.4    109.0    0.008     52.0     96.4
Hairspray                128.0    143.2    5.011     78.3    142.4
Harry Potter and the     115.8    130.7    1.001     65.7    130.8
Order of the Phoenix

Hot Rod                  113.7    127.5    1.036     69.1    131.1
I Know Who Killed Me     109.4    125.5    0.254     57.6    120.9
1 Now Pronounce You      127.0    143.5    3.419     75.4    139.7
Chuck and Larry
Knocked Up               123.8    137.4    0.382     59.0    123.9
Last Legion              116.8    120.3    3.946     77.8    140.7

License to Wed           129.1    141.5    0.767     66.5    128.9
Live Free or Die Hard    118.5    133.0    2.520     72.4    137.5
No Reservations          121.7    133.4    0.200     55.9    119.2
Ratatouille              125.0    143.7    1.620     70.4    134.3
Rescue Dawn              113.4    121.6    1.258     67.5    132.5

Rush Hour 3              118.8    117.0    4.784     80.2    142.1
Skinwalkers              118.3    141.5    1.646     72.0    134.4
Stardust                 113.1    124.5    2.874     73.5    138.4
Sunshine                 115.5    117.0    1.420     69.8    133.3
The Bourne Ultimatum     110.0    128.9    0.434     60.8    124.8

The Simpsons Movie       128.6    142.5    0.100     56.2    118.1
Transformers             133.9    144.7    4.414     75.9    141.5
Underdog                 110.5    127.4    1.744     73.0    134.8
Who's Your Caddy?        128.2    144.3    3.720     78.3    140.3
You Kill Me              109.0    126.3    0.107     52.1    114.7

Key: Max = the maximum sound level; Lpk = the peak sound level
that the microphone detected; Dose = dose reading where a value
of 100% is the maximum allowable exposure to accumulated
continuous noise; Lavg = average sound level; SEL = sound
exposure level.

Table 3. Cumulative amount of time movie-goers were exposed to
different sound exposure levels

Title                    [greater than or   [greater than or
                         equal to] 90 dBA   equal to] 100d-BA

                               Measured in minutes unless
                                     otherwise noted

Becoming Jane                   40                  6
El Cantante                     69                 32
Evening                         20               7.5 sec
Hairspray                      108                 55
Harry Potter and the            55                 13
  Order of the Phoenix
Hot Rod                         53                 12
I Know Who Killed Me            29                  4
I Now Pronounce You            110                 38
  Chuck and Larry
Knocked Up                      75                  7
Last Legion                     74                 32
License to Wed                  53                  7
Live Free or Die Hard           90                 26
No Reservations                 22               11 sec
Ratatouille                     73                 16
Rescue Dawn                     46                 14
Rush Hour 3                     78                 42
Skinwalkers                     62                 21
Stardust                        68                 29
Sunshine                        61                 17
The Bourne Ultimatum            42                  5
The Simpsons Movie              31                  2
Transformers                   126                 50
Underdog                        69                 23
Who's Your Caddy?               81                 36
You Kill Me                     13                  2

Title                    [greater than or    [greater than or
                         equal to] 110 dBA   equal to] 120 dBA

                              Measured in minutes unless
                                    otherwise noted

Becoming Jane                  7 sec              2.5 sec
El Cantante                      2                <1 sec
Evening                         --                  --
Hairspray                     33 sec               8 sec
Harry Potter and the           3 sec                --
  Order of the Phoenix
Hot Rod                       6.5 sec               --
I Know Who Killed Me            --                  --
I Now Pronounce You           45 sec               2 sec
  Chuck and Larry
Knocked Up                       4                   1
Last Legion                      4                  --
License to Wed                <1 sec                --
Live Free or Die Hard         50 sec                --
No Reservations                4 sec                --
Ratatouille                   49 sec               7 sec
Rescue Dawn                   21 sec                --
Rush Hour 3                      3                  --
Skinwalkers                      1                  --
Stardust                      40 sec                --
Sunshine                      19 sec                --
The Bourne Ultimatum           4 sec                --
The Simpsons Movie             3 sec              <1 sec
Transformers                  18 sec               9 sec
Underdog                       1 sec                --
Who's Your Caddy?                1                 2 sec
You Kill Me                     --                  --

Title                     [greater than or
                          equal to] 130 dBA

                          Measured in minutes
                         unless otherwise noted

Becoming Jane                   --
El Cantante                     --
Evening                         --
Hairspray                       --
Harry Potter and the            --
  Order of the Phoenix
Hot Rod                         --
I Know Who Killed Me            --
I Now Pronounce You             --
  Chuck and Larry
Knocked Up                      --
Last Legion                     --
License to Wed                  --
Live Free or Die Hard           --
No Reservations                 --
Ratatouille                     --
Rescue Dawn                     --
Rush Hour 3                     --
Skinwalkers                     --
Stardust                        --
Sunshine                        --
The Bourne Ultimatum            --
The Simpsons Movie              --
Transformers                   1 sec
Underdog                        --
Who's Your Caddy?               --
You Kill Me                     --
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Title Annotation:ORIGINAL ARTICLE
Comment:Noise exposure in movie theaters: a preliminary study of sound levels during the showing of 25 films.(ORIGINAL ARTICLE)
Author:Warszawa, Anna; Sataloff, Robert T.
Publication:Ear, Nose and Throat Journal
Article Type:Report
Geographic Code:1USA
Date:Sep 1, 2010
Words:2843
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