Audiological and noise exposure findings among members of a Brazilian folklore music group

Abstract

BACKGROUND:

Musicians and dancers can be considered an at-risk population for developing noise-induced hearing loss.

OBJECTIVES:

To determine the audiological profile of members of a folklore-related music group and quantify noise exposure at their rehearsal venue.

METHODS:

This was a quantitative and descriptive study. The musicians and dancers were evaluated in two stages: an interview about their working life, followed by high frequency tonal audiometry. The sound pressure level in the group’s rehearsal venue was measured using a BEK 2270 Noise Analyzer.

RESULTS:

A total of 7.2% of the subjects had noise-induced hearing loss (NIHL) and 39% of the audiometric tests were notch type. During the interview 31.7% of the subjects mentioned discomfort from loud noise, although none of them used ear protection. The environmental assessment showed inadequate humidity and oscillating temperature. Twenty sound pressure level measurements were performed for Leq (equivalent sound pressure levels) and the results ranged from 88 dB (A) to 99 dB (A) with a mean of 97.05.

CONCLUSIONS:

Exposure to high levels of sound pressure has led to NIHL in some members of the group. Some of those with normal hearing also presented a notch configuration characteristic of NIHL. Tinnitus, indicating that a change in hearing has occurred, was the most frequent auditory symptom.

Keywords

Music noise induced hearing loss occupational noise tinnitus

1 Introduction

Studies on the effects of noise have identified it as a public health problem and one of the forms of pollution that most affects people [1]. Additionally, study addressed to evaluate personal and work-related demands and resources associated with psychological distress in professional musicians showed both were associated with symptoms of anxiety and depression among musicians [2]. Lastly, the studies approach more psychosocial risk factors for musculoskeletal problems and functional disorders [3] among musicians [4], but there are some questions that need more research, as the exposure to loud noise.

Exposure to loud noise is a common feature of industrial settings, and with the development of modern sound amplification equipment it has also become a factor for professional musicians. Although music is not technically noise, exposure to high sound pressure levels can still cause changes in hearing [5]. Compared to the general population, professional musicians have a significant risk of hearing change due to exposure to high levels of noise at work [6]. A Norwegian study found hearing loss in 37.8% of rock musicians [7]. In Finland, orchestra musicians were found to have hearing loss at frequencies above 3 kHz [8].

Australia, Finland and Switzerland have become sufficiently concerned with the limits of occupational sound exposure during musical activities, both for musicians and their audiences, that they have established preventive measures for hearing health [9]. In Sweden, occupational safety recommendations limit daily exposure to noise during an eight-hour work shift to 85dB due to the risk of hearing loss. At concerts the maximum recommended sound level is 115Db [10]. In the United States, agencies such as United States Department of Health and Human Services, OSHA and NIOSH recognize the hearing risk to which musicians are exposed when subjected to high sound pressure levels [8]. In Brazil, however, there is still no specific legislation addressing the risk of hearing loss for professional musicians and no guidelines regarding noise control in leisure activities have been developed by the Brazilian Association of Technical Norms (ABNT) [9].

The cultural expression of the musical group Bumba-Meu-Boi is a worldwide reference and the variety of musical styles represented by this group has been agreed to divide them into five accents: Ilha, Guimarães, Baixada, Cururupu and Orchestra [10]. The group has an intense work rhythm, around 3 and a half hours a day, and intensify in festive seasons [11 –14]. Due to the routine of tests and the physical structure of the place where they happen, the components of this group can be considered at risk population to develop noise-induced hearing loss (NIHL).

Due to the work routine and the type of structures in which rehearsals take place, musicians and dancers can also be considered an at-risk population for developing NIHL. Assessment of these entertainers’ audiological profile, including signs and symptoms of hearing loss, as well as their work environment, can serve as a basis for developing health monitoring and promotion programs. Pursuant to these goals, the present study aimed to determine the audiological profile of the members of a large music group and quantify noise exposure at their rehearsal venue.

2 Materials and methods

This was a quantitative study with a descriptive and analytics approach. The musicians and dancers of the Brazilian popular culture music group Bumba-Meu-Boi were evaluated. The cultural expression of Bumba-Meu-Boi [11], which plays a broad repertoire of styles, is a world reference in its genre.

The group practices four hours a day, although its schedule intensifies prior to festivals. Data were collected between May and June 2017. The inclusion criteria were participants without present external/middle ear impairment or impacted cerumen, as well as age over 18 years. Members with proven hearing impairment were excluded (e.g. those who used hearing aids), as were those with neurological, psychiatric and/or cardiac problems.

Assessment of the rehearsal venue’s acoustic environment included photographic analysis. To investigate the sound exposure of the musicians and dancers, the sound pressure levels were measured during group rehearsals. The exposure limits, as well as the exchange rate, were based on regulatory standards from the Brazilian Ministry of Labor (NR15 and NHO-01) [12, 13], U.S. National Institute for Occupational Safety and Health criteria for noise exposure [14] and EU noise regulations (Directive 2003/10/EC) [15]. These standards were selected due to their wide use in noise studies. The ambient sound at the rehearsal venue was measured using a properly calibrated Bruel & Kjær Type 2270 Sound Level Meter, according to IEC 60651, IEC 60804 and IEC 61672-3:2006. The measurements were taken every 10 minutes between 7:00 pm and 10:00 pm alongside and in front of the band and dancers. Twenty measurements of sound pressure levels were performed, the first at 7:00 pm and the last at 10:00 pm. The Leq average found was 97.05. The highest level in dB (A) was at the time of measurements 3, 8, 11 and 17 with 99 dB (A) and the lowest was at the time of measurement 20 at 88 dB (A).

The audiological evaluation consisted of a 14-hour auditory rest. A visual inspection of the external auditory meatus was performed to verify obstructions that could prevent audiological evaluation. After the evaluation, the members answered a questionnaire about socio-demographic and occupational data: their function and history in the group, the number of days and hours they rehearsed weekly and the use of ear protection and personal protective equipment. Auditory symptoms and extra-auditory effects were assessed. Threshold tonal audiometry was performed through the airway at frequencies of 0 to 8000 Hz, as well as through bone at frequencies of 500 to 4000 Hz when the airway thresholds were above 25 dBHL. Auditory thresholds less than or equal to 25 dB (A) were considered at all examined frequencies, as well as notch configuration (suggestive of NIHL), which includes lower thresholds at frequencies of 3000Hz to 6000Hz and higher thresholds at 8000Hz. An Interacoustics AC33 audiometer was used for these tests.

Data on the participants’ audiological, social and occupational profiles are presented in absolute numbers and percentages. In association analyzes were used the Chi-square test or Fisher’s exact test. For statistical significance was assumed a descriptive level of 5% (p < 0.05). The data were analyzed in SPSS 18.0. This study was approved by the Research Ethics Committee of Ceuma University (case 1532544) and adhered to the norms of Brazilian National Health Council Resolution 466/12.

3 Results

A total of 41 members of Bumba-Meu-Boi participated in the study. Table 1 shows the participants’ demographic, occupational and self-perception data. The sample was 58.5% male, 51.2% of the participants were between 18 and 25 years old and 56.1% were dancers. A total of 75.5% rehearsed at least 2 hours per day and 70.7% of them rehearsed five times a week. Regarding exposure time, 56.1% of the members had been in the group between 1 and 5 years. When asked about their perception of the sound intensity at rehearsals, 61% found it unpleasant.

Table 1
Group member demographic and occupational characteristics (N = 41)

Variables Categories n(%)

Gender Male 24 (58.5)

Female 17 (41.5)

Age (years old) 18–25 21 (51.2)

26–35 11 (26.8)

26–45 5 (12.2)

46–55 4 (9.8)

Function in group Musician 18 (43.9)

Dancer 23 (56.1)

Works in a noisy environment No 33 (80.5)

Yes 8 (19.5)

Hours of rehearsal per day 1 2 (5.0)

2 31 (75.6)

3 4 (9.7)

4 4 (9.7)

Rehearsals per week 3 8 (19.5)

4 4 (9.8)

5 29 (70.7)

Group membership time (years) 1–5 23 (56.1)

6–10 7 (17.0)

11–15 2 (4.9)

16–25 5 (12.2)

26–35 4 (9.8)

Variables	Categories	n(%)
Gender	Male	24 (58.5)
	Female	17 (41.5)
Age (years old)	18–25	21 (51.2)
	26–35	11 (26.8)
	26–45	5 (12.2)
	46–55	4 (9.8)
Function in group	Musician	18 (43.9)
	Dancer	23 (56.1)
Works in a noisy environment	No	33 (80.5)
	Yes	8 (19.5)
Hours of rehearsal per day	1	2 (5.0)
	2	31 (75.6)
	3	4 (9.7)
	4	4 (9.7)
Rehearsals per week	3	8 (19.5)
	4	4 (9.8)
	5	29 (70.7)
Group membership time (years)	1–5	23 (56.1)
	6–10	7 (17.0)
	11–15	2 (4.9)
	16–25	5 (12.2)
	26–35	4 (9.8)

Table 2 presents data concerning auditory symptoms and extra-auditory effects. The most notable auditory symptoms were tinnitus 65.9% and otalgia 29.3%; among the extra-auditory effects, frequent tiredness (41.5%) stood out. It is worth noting that, although only 7.2% of the subjects presented NIHL, 39% of the audiometric tests detected notch-type responses, 31.7% reported difficulty hearing the radio or television in a noisy environment, 31.7% reported discomfort from loud sounds and 36.6% reported mood swings. Among those with notch-type audiometric configuration, 61.1% were musicians and 34.8% were dancers (Table 3). The analysis between the socio-labor and notch/NIHL variables (Table 3) shows that only the variable test days per week showed a statistically significant association with notch/hearing loss (p = 0.018). The other variables showed no statistically significant association.

Table 2

Frequency of auditory symptoms and extra-auditory effects and hearing loss among group members (N = 41)

Variables	Categories	n (%)
Tinnitus	No	14 (34.1)
	Yes	27 (65.9)
Otalgia	No	29 (70.7)
	Yes	12 (29.3)
Difficulty conversing in a noisy environment	No	33 (80.5)
	Yes	8 (19.5)
Difficulty hearing radio/TV	No	28 (68.3)
	Yes	13 (31.7)
Discomfort from loud sounds	No	28 (68.3)
	Yes	13 (31.7)
Dizziness	No	33(80.5)
	Yes	8 (19.5)
Difficulty paying attention	No	32 (78.0)
	Yes	9 (22.0)
Sleep alterations	No	31 (75.6)
	Yes	10 (24.4)
Change in humor	No	26 (63.4)
	Yes	15 (36.6)
Headaches	No	33 (80.5)
	Yes	8 (19.5)
Frequent fatigue	No	24 (58.5)
	Yes	17 (41.5)
Digestive disorder	No	35 (85.4)
	Yes	6 (14.6)
Hearing loss	No loss	22 (53.8)
	Notching only	16 (39.0)
	Slight loss	1 (2.4)
	Slight loss with notching	1 (2.4)
	Moderate loss with notching	1 (2.4)

Table 3

Association between social, labor, and hearing loss (N = 41)

	NIHL/Hearing loss
Variables	No		Yes		p
	n	(%)	n	(%)
Sex
Male	11	(45.8)	13	(54.2)	0.233
Female	11	(64.7)	6	(35.3)
Age (years)
15–35	19	(59.4)	13	(40.6)	0.206
36–55	3	(33.3)	6	(66.7)
Function in the group
Musician	7	(38.9)	11	(61.1)	0.093
Dancer	15	(65.2)	8	(34.8)
Works in noisy environment
No	20	(60.6)	13	(39.4)	0.115
Yes	2	(25.0)	6	(75.0)
Rehearsal hours per day
1 a 2	16	(48.5)	17	(51.5)	0.249
3 a 4	6	(75.0)	2	(25.0)
Days per week
Equal to 5	3	(25.0)	9	(75.0)	0.018^*
< 5	19	(65.5)	10	(34.5)
Participation time (years)
1–10	18	(60.0)	12	(40.0)	0.179
11–25	4	(36.4)	7	(63.6)
Noise impairs testing
Yes	9	(64.3)	5	(35.7)	0.326
No	13	(48.1)	14	(51.9)

Fisher’s exact test for age and rehearsal hours per day; Chi-square for sex, function in the group, works in noisy environment, days per week, participation time, noise impairs testing. ^*p-values<0.05.

When asked about hearing protection, none of the participants reported using hearing protection devices. In fact, 94% did not even understand what hearing protection meant.

When they asked, why not make use of the same, the most frequent answers were:

“I forgot to bring my today! You have a cotton to lend me my place. But, I swear that this year I use. I need to use it, I was forgetting today!”

“I don’t need to use! I’m a singer, honey!”

“Dancer need? Nor do I know well what is this!”

“I know what it is, I had this class at the university. It’s a lack and shame in the face even, because I know that we need!”

There was no type of safety management program at the rehearsal venue. Ten speakers were stacked up behind the band, rather than being distributed throughout the space. The rehearsal space had no sound insulation (e.g. for the drum kit); the speakers and amplifiers were very close to each other and to the musicians and dancers. Other acoustic problems included inadequate humidity and oscillating temperature. Twenty sound pressure level measurements were performed; Leq (equivalent sound pressure levels) ranged from 88 dB (A) to 99 dB (A), with a mean of 97.05.

4 Discussion

People exposed to high levels of sound pressure are at risk of NIHL, and this risk can increase with exposure time [14, 16]. In this study, tinnitus was the main auditory symptom. This symptom is the first to appear in subjects exposed to high levels of sound pressure, a fact that calls for periodic assessments of hearing health.

One study on the prevalence of auditory symptoms among workers exposed to occupational noise found that tinnitus is a frequent complaint in this population [17]. Other studies on pop musicians also found this to be the most frequent symptom [18, 19]. Testing for auditory symptoms and extra-auditory effects in musicians should be routine, since these signs affect performance and work quality, provoke irritability, lead to frequent headaches, sleep disorders and, consequently, lower quality of life [20, 21]. Another study found tinnitus in 56.5% of musicians and intolerance to loud sounds in 30.4%. Extra-auditory complaints have also been reported, including insomnia (26.1%) and memory problems (26.1%) [18]. According to audiological evaluations of professional pop, rock and jazz musicians, the longer the time in the band and the higher the number of weekly rehearsal hours, the greater the relationship between notch configuration and tinnitus [22].

Of the audiometric configurations found in this study, 39% were within the normal range, although they all had a common characteristic: a notch configuration that included losses at frequencies from 4000 to 6000Hz, which is the main characteristic of NIHL. In other studies on musicians, we found an association between tinnitus, sound discomfort and notch configuration [7]. In a study by other authors, the audiograms of 79% of the assessed musicians were within normality, except for losses between 3000 and 6000Hz [16, 17]. Thus, musicians are exposed to higher noise levels than allowed by regulatory standards, and such exposure increases the chance of developing NIHL [23 –25]. There is a significant correlation between NIHL and years of exposure to high sound pressure, i.e. the longer the exposure time to high noise levels, the higher the probability of hearing loss [24]. Other research corroborates this assertion, emphasizing concerns about the effects of noise intensity and exposure duration among musicians [5]. The present study found that not only are musicians subject to NIHL, but dancers as well, although little research has been directed towards this profession. The dancers presented normal hearing, but with notch-type configuration.

Investigations of hearing protection use among musicians have found that although musicians report satisfaction with the protection and agree that it is important, they did not use it full-time [26, 27]. A study on hearing protection awareness and the relationship between personal and collective worker safety found that workers did not use protection even when available in the workplace [28]. Hearing protection is mandatory for workers exposed to high levels of sound pressure, but such devices must be adequate for the type of work, exposure duration, instrument type and the shape of the ear. College instrumental musicians also report never having received any training about hearing health and only a small percentage used some type of hearing protection. When questioned why they didn’t use it, the most commonly cited reason was the negative impact on hearing quality [28]. Neglect of hearing protection was also found among participants in this study, i.e., some did not use protection although they understood its importance. The results indicate that this behavior should change. Hearing health programs should be developed whose priority is raising awareness about the use of hearing protection to bring about paradigm shifts.

The sound pressure level assessment showed that group members are exposed to intensities that put their hearing at risk. According to Brazilian labor laws, the ear should be exposed to no more than 92 dB for a maximum of three hours [12]. In another study, after orchestral musicians were exposed to an equivalent continuous sound pressure level (Leq) of 79.4 dB, their audiograms presented a notch-type configuration, and this audiometric profile took 8 hours after exposure to return to normal [29].

Although both musicians and industrial workers are exposed to noisy surroundings, it is believed that musicians are somehow less susceptible to hearing loss than people who work in a factory setting. This interpretation stems from the fact that exposure to loud music occurs intermittently, with varying time between shows and rehearsals, while industrial noise tends to be continuous. Brazilian regulatory standards (NR15) [12] indicate that the level of sound pressure to which musicians can remain exposed depend on exposure duration. The noise level could only remain at 99dB, a value found in this study, for one hour a day, which includes both rehearsals and shows. Under such conditions, there are losses in the intelligibility of language, which thus impairs communication.

The group’s rehearsal venue was devoid of acoustic treatment to minimize the effects of noise. The noise levels emitted during rehearsal were above the limits established by both municipal and federal (NBR 10.151) legislation [30]. NBR 10.151 sets a limit of 50 dB for sound levels in outdoor environments.

Musicians are often exposed to high sound pressure levels and are at risk of developing NIHL due to routine individual or group rehearsals and public shows. Since music is viewed as a leisure activity, hearing is generally not addressed as a health issue. A musician’s hearing is one of the tools of his trade and influences both his work quality and the longevity of his career. It was observed that the rehearsal venue controls neither the quantity nor intensity of sound, and the use of hearing protection is not part of the group’s organizational culture.

This study has some limitations that should be considered, the small sample size was due to the group’s recent reorganization and the director’s reluctance to allow more members to be evaluated. Longitudinal studies including a larger sample of musicians, differentiated according to genre, instrument and exposure duration to high levels of sound pressure. Nevertheless, these factors, when correlated with NIHL, could help develop measures aimed at environmental acoustic control, hearing protection training, periodic audiometric exams and educational programs on hearing health.

5 Conclusions

In the study population, tinnitus and discomfort from loud sounds were the most frequent hearing complaints. It was observed that the more days a member rehearsed, the greater the notch-type results in the audiometric test. The notch configuration was prevalent in the audiometric assessments. None of the group members used hearing protection. The sound pressure levels at the rehearsal venue were above those recommended by national standards. No acoustic treatment was found at the rehearsal venue to attenuate the noise. The lack of use of personal protective equipment, as well as the sound levels above the permitted levels may cause future hearing problems of this population. In this regard, protective measures and education in this regard should be taken to avoid loss hearing

Conflict of interest

None to report.

References

Portela

, Queiroga

, Constantini

, Zannin

PHT

. Annoyance evaluation and the effect of noise on the health of bus drivers. Noise Health. 2013;15:301–6.

Aalberg

, Saksvik-Lehouillier

, Vaag

. Demands and resources associated with mental health among Norwegian professional musicians. Work. 2019;63:39–47.

Lima

, Pinheiro

TMM

, Dias

, Andrade

. Development and prevention of work related disorders in a sample of Brazilian violinists. Work. 2015;51:273–80.

Jacukowicz

. Psychosocial work aspects, stress and musculoskeletal pain among musicians. A systematic review in search of correlates and predictors of playing-related pain. Work. 2016;54:657–68.

Lüders

, Gonçalves

CGO

, Lacerda

ABM

, Schettini

SRL

, Silva

LSG

, Albizu

, Marques

. Hearing and quality of life in musicians of a symphonic orchestra. Audiol Commun Res. 2016;21:e1688.

Schink Tania , Kreutz

, Busch

, Pigeot

, Ahrens

. Incidence and relative risk of hearing disorders in professional musicians. Occup Environ Med. 2014;71(7):472–6.

1Stormer

, Laukli

, Høydal

, Stenklev

. Hearing loss and tinnitus in rock musicians: A Norwegian survey. Noise Health. 2015;17:411–21.

Toppila

, Koskinen

, Pyykkö

. Hearing loss among classical-orchestra musicians. Noise Health. 2011;13:45–50.

Lee

GJC

, Lim

, Kuan

AYW

, Teo

JHW

, Tan

, Low

. The music listening preferences and habits of youths in Singapore and its relation to leisure noise-induced hearing loss. Singapore Med J. 2014;55(2):72–7.

10.

Kähärit

, Zachau

, Eklöf

, Sandsjö

, Möller

. Assessment of hearingand heraing disorders in rock/jazz musicians. Int J Audiol. 2003;42(5):279–88.

11.

Ribeiro

. A dança do Bumba-meu-boi do Maranhão. São Luís: Iphan 2010.

12.

Brasil. Ministério do Trabalho. Segurança e Medicina do Trabalho. Norma Regulamentora –NR atividades e operações insalubres. Brasília: MS; 2015.

13.

FUNDACENTRO - Fundação Jorge Duprat Figueiredo de Segurança e Medicina do Trabalho. Norma de Higiene Ocupacional –Procedimento Técnico: Avaliação da exposição ocupacional ao ruído –NHO 01. 2001. 41 f. Ministério do Trabalho e Emprego MTE. Brasília, 2001.

14.

¥Roberts

, Seixas

, Mukherjee

, Neitzel

. Evaluating the Risk of Noise-Induced Hearing Loss Using Different Noise Measurement Criteria. Annals of Work Exposures and Health. 2018;62(3):295–306.

15.

European Union. Regulations Implementing the Physical agents (Noise) Directive (2003//10/EC). 2013. [acesso 2017 jan. 18]. Disponível em: http://www.azores.gov.pt/NR/rdonlyres/7C6D-3A96–BED3-9A238CD715D7/23/Directiva10CEprescri% C3% A7% C3% B5esruidolaboral.pdf".

16.

Régis

ACFC

, Crispim

KGM

, Ferreira

. Incidence and prevalence of noise induced hearing loss in workers of a metallurgical company in Manaus –AM, Brazil. Rev CEFAC. 2014;16(5):1456–62.

17.

Samelli

, Matas

, Carvallo

, Gomes

, Beija

, Magliaro

et al.. Audiological and electrophysiological assessment of professional pop/rock musicians. Noise Health. 2012;4:6–12.

18.

Antas

OFSBCS

, Silva

, Mascarenhas

, Souza

, Andrade

WTLl

. Nuisance generated by urban noise among traders around a public market in João Pessoa, PB. R Bras Ci Saúde. 2014;18(2):97–102.

19.

Munhoz

, Lopes

. Hearing loss prevention program (HLPP) for musicians. Revista Portuguesa de Saúde Ocupacional. 2016;1(22):1–9.

20.

Oliveira

, Santos

, Rabelo

ATV

, Magalhães

. The impact of noise exposure on workers in Mobile Support Units. CoDAS. 2015;27(3):215–22.

21.

Esteves

, Brandão

, Siqueira

CGA

, Carvalho

SAS

. Hearing, Tinnitus and Life Quality: a pilot study. Rev CEFAC. 2012;14(5):836–43.

22.

Halevi-Katz

, Yaakobi

, Putter-Katz

. Exposure to music and noise-induced hearing loss (NIHL) among professional pop/rock/jazz musicians. Noise Health. 2015;17:158–64.

23.

Chung

, Chu

, Cullen

. Hearing effects from intermittent and continuous noise exposure in a study of Korean factory workers and firefighters. BMC Public Health. 2012;12:80–7.

24.

Oliva

, Morata

, Lacerda

ABM

, Steinmetz

, Bramatti

, Vivan

, Gonçalves

CGO

, Marques

. Significant auditory threshold shift among workers exposed to different noise levels. Rev Soc Bras Fonoaudiol. 2011;16(3):260–5.

25.

Guida

, Diniz

, Chagas

PSC

, Kinoshita

. Audiology profile in the military police State of São Paulo. Arq Int Otorrinolaringol. 2010;14(4):426–32.

26.

Azevedo

, Oliveira

. Hearing of professional violinists: cochlear function and auditory symmetry study. Rev Soc Bras Fonoaudiol. 2012;17(1):73–7.

27.

Huttunen

, Sivonen

, Poykko

. Symphony orchestra musicians’ use of hearing protection and attenuation of custom-made hearing protectors as measured with two different real-ear attenuation at threshold methods. Noise Health. 2011;13(51):176–88.

28.

Olson

, Gooding

, Shikoh

, Graf

. Hearing Health in College Instrumental Musicians and Prevention of Hearing Loss. Med Probl Perform Art. 2016;31(1):29–36.

29.

Dudarewicz

MPŁ

, Małgorzata

, Kamil

. Exposure to excessive sounds during orchestra Rehearsals and temporary hearing changes In hearing among musicians. Med Pr. 2015;66(4):479–86.

30.

Gonçalves

, Matsunaga

, Silva

, Miranda

. Noise analysis of nightclubs and bars in residential areas in Anápolis-GO and impact in the neighborhood. Rev Mirante. 2016;9(2):268–82.