Home Email this page Print this page Bookmark this page Decrease font size Default font size Increase font size
Noise & Health  
Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Email Alert *
Add to My List *
* Registration required (free)  

   Article Tables

 Article Access Statistics
    PDF Downloaded39    
    Comments [Add]    

Recommend this journal


  Table of Contents    
Year : 2013  |  Volume : 15  |  Issue : 66  |  Page : 296-300
Portable music player users: Cultural differences and potential dangers

1 Department of Speech-Language-Hearing Sciences, Lehman College, The City University of New York, USA
2 Director of Diagnostic Audiology, Boston Children's Hospital, Instructor in Otology and Laryngology Harvard Medical School, USA
3 The Graduate Center, Linguistics, Department Department of Middle & High School Education, Lehman College, City University of New York, Lehman College, USA
4 Department of Middle & High School Education Lehman College, City University of New York, USA

Click here for correspondence address and email
Date of Web Publication17-Aug-2013

Many studies have examined the use of portable music players portable listening devices (PLDs) from various ethnic groups. Some findings suggest that there may be differences among ethnic groups that lead to louder or longer listening when using PLD devices. For example, some studies found that Hispanic PLD users listen at higher volume levels while other studies found that African American PLD users listen at higher volume levels. No investigator has explained the reasons for differences among ethnic groups in listening intensity. This paper will address the possible reasons for these differences and offer guidelines for the prevention of noise-induced hearing loss.

Keywords: Cultural differences, noise-induced hearing loss, portable music players

How to cite this article:
Levey S, Fligor BJ, Cutler C, Harushimana I. Portable music player users: Cultural differences and potential dangers. Noise Health 2013;15:296-300

How to cite this URL:
Levey S, Fligor BJ, Cutler C, Harushimana I. Portable music player users: Cultural differences and potential dangers. Noise Health [serial online] 2013 [cited 2023 Dec 5];15:296-300. Available from: https://www.noiseandhealth.org/text.asp?2013/15/66/296/116553

  Introduction Top

Many portable listening device (PLD) users listen too loud and too long (Levey et al., 2011) [1] PLD users may be at risk for noise-induced hearing loss (NIHL) if they use these devices at high volumes for lengthy periods of time (Fligor, 2006). [2] One of the primary causes of NIHL is recreational noise (Peng et al., 2007; Weichbold and Zorowka, 2007), [3],[4] such as the use of PLDs, e.g., CDs, iPods, and MP3 players. NIHL results from exposure to sounds that are excessively intense, above 85 dBA, given sufficient exposure time, according to the National Institute on Deafness and other Communication Disorders (NIDCD, 2007). [5] The most significant characteristic of NIHL is that it is insidious, with listeners frequently unaware that a hearing disorder is the present until a significant damage has occurred (NIDCD, 2007). [5]

Noise-induced hearing loss

The NIDCD (2007) [5] has attempted to help PLD users understand the effect of noise on hearing. Sound waves enter the outer ear and travel through the ear canal to the eardrum, which vibrates from the incoming sound waves. These vibrations are sent to the middle ear. Here, bones (ossicles) in the middle ear (malleus, incus, and stapes) amplify sounds, sending vibrations to the inner ear. Hair cells (sensory cells) are in the inner ear and are the sensory receptors of sound. Damage to hair cells results in decreased hearing sensitivity while continuous exposure to loud noise can damage the structure of hair cells. Specifically, hair cells go through a cascade of chemical events that leads to cell death (Henderson et al., 2006). [6] In this event, there may be hearing loss and tinnitus (phantom noises, ringing or roaring sounds in the ears or head). This leads to a high frequency hearing loss, affecting the perception of sounds such as "s" and "f" (e.g., see and fee). However, individuals with a high frequency hearing loss are less likely to notice or to report this loss than those with a lower frequency hearing loss. That is why NIHL is insidious: The PLD user is unaware that a hearing loss is developing or present until more significant damage occurs.

The potential of hearing loss with portable listening device use

Levey et al., (2011) [1] measured free-field equivalent sound levels from PLD headphones on a mannequin with a calibrated sound level meter (Martin and Martin, 2007). [7] Participants consisted of 189 college students, averaging 22.2 years of age. Findings were that 58.2% of participants exceeded recommended sound exposure limits, placing them at risk for NIHL. Rawool and Wayne (2008) [8] surveyed the auditory life-styles and beliefs of college students. Respondents reported 44% using noisy equipment without the use of ear protection. There were 69 students who reported working in noisy environments, but only 10 reported the use of hearing protection. The most alarming result of this study was that 50 of the 69 (73%) students who worked in noisy environments reported tinnitus. In summary, the choices of college students place them in risks for NIHL. In the same study, approximately 50% of the students either moderately (43.7%) or strongly (7.14%) agreed to the statement "When I am listening to my headphones, people next to me can hear my music," suggesting relatively high sound exposure.

A questionnaire survey of 428 college-aged PLD users found that a third reported listening to music at full volume levels (Hoover and Krishnamurti, 2010). [9] A survey of 1,687 Dutch 12-19 years olds found that 90% reported listening to music on PLDs, with 28.6% placed at risk for hearing loss due to estimated exposure of 89 dBA for ≥1 h/day (Vogel et al., 2011). [10] A questionnaire survey of 28 students, 17-23 years of age, showed that they reported at least one symptom of possible NIHL (McNeill et al., 2010). [11] A questionnaire survey of 9,693 young adults found that the majority reported tinnitus after listening to loud music (Chung et al., (2005). [12] The music television website revealed that 32% of 2,500 random responses to the website reported symptoms of hearing loss (Quintanilla-Dieck Mde et al., 2009). [13] Laboratory studies have found that PLD users' volume levels ranged from 79 to 125 dBA (Keith et al., 2008). [14] A study that combined laboratory and real-word field study in public environments in Helsinki, Finland (Airo et al., 1996) [15] found that the average listening level was 82 dBA for the 60 participants, with a range from 61 to 104 dBA. These higher levels place PLD users at risk for NIHL.

One of the primary causes of NIHL among younger individuals is listening to recreational noise (Peng et al., 2007; Weichbold and Zorowka, 2007). [3],[4] PLD users may be at risk for NIHL if they use these devices at high volumes for long periods of time (Fligor, 2006). [2] As far back as 20 years ago, investigators found that the percentage of second graders with hearing loss had increased 2.8 times from measures that had been taken 10 years earlier (Montgomery and Fujikawa, 1992). [16] Measures from 15 years ago found that 1% of the school-age population had some degree of hearing loss (Blair et al., 1996), [17] whereas figures from 2001 reported symptoms of NIHL in 12% of children ages 6-19 years (Niskar et al., 2001). [18]

Ethnic differences and the use of PLDs

Ethnic differences have been reported in the intensity and duration when using PLDs. Zogby (2006) [19] used a telephone survey of adults and high school aged students, which examined the use of personal electronic devices and head phones. Survey respondents included African Americans, Asians, Pacific Islanders, Native Americans, Alaskan natives, and other/mixed ethnic individuals. This survey found that high school students were more likely to report what the authors of this survey considered symptoms of NIHL,: saying "what" or "huh" when having a conversation, having to turn up the volume on the television, and tinnitus or ringing in the ears. Among the student respondents, African Americans (72%) and Hispanics (56%) were more likely than whites (48%) to report that they had some of these symptoms of hearing loss. In addition, Hispanic teens, compared to teens in general, were reported to use iPods and other PLDs for longer periods and at higher volumes (Zogby, 2006, p. 6). [19]

A survey conducted by Torre (2008) [20] found that African American participants were significantly more likely to report listening between 3 h and 5 h or longer than any of the other groups that were investigated (Hispanic or Latino, American Indian/Alaskan; Hawaiian/Pacific Islander; Black/African American; and White participants). African Americans were also significantly more likely to report listening at a "very loud volume."

Although these studies report ethnic differences in PLD use, the findings are questionable in the level of evidence to explain these differences. First, actual use of PLDs is not measured in survey studies. For example, PLD users are found to increase their listening levels from 6 to 10 dB louder when traveling on subways or walking on the street when using non-sound isolating earphones (Hodgetts et al., 2007), [21] given the ambient noise in both contexts. Thus, they may actually listen louder than they report in these surveys. Second, PLD users may not want to report that they listen loud (or the opposite), or may not be aware of their listening volumes. For example, teenagers frequently play their music at a higher intensity than other PLD users, while not perceiving the relative loudness of their devices (Portnuff et al., 2011). [22] For example, Portnuff et al., found that that a substantial number of these adolescents, aged 13-17 years of age, listened at levels that placed them at risk for NIHL while laboratory measures had only a low to moderate correlation with self-reported typical listening levels. Third, no study contained an explanation for the cultural differences. This is important as listeners may draw their own conclusions and mistakenly decide that the PLD user is intentionally listening too loud. In summary, these surveys report findings that are based on incomplete evidence.

Research regarding ethic differences

Levey and Fligor (2011) [23] examined the volume level of PLD users in two contexts: 117 college students on a New York City campus and 43 individuals passing through the noisier environment of Union Square in New York City. There were 196 participants invited to have their earphone levels measured and to complete a questionnaire that asked for demographic information, including their report of ethnic/racial identity. Final analysis examined 160 of the earphone levels of participants who completed all information of the questionnaire. Participants averaged 25 years of age (M = 22.0, SD = 8.15, Mdn = 22.0), with 89 females and 71 males. Ethnic breakdown consisted of 10 Africans, 28 African Americans, 5 Asians, 13 Caribbeans, 66 Hispanics, and 38 Whites. These investigators also examined the role of music genre to determine if music differences might account for differences in listening levels. Listening level differences may be associated with certain genres, given that high volume is a characteristic of the production of rap music (Rose, 1994). [24] These investigators collapsed the types of music people were listening to into the following categories: Alternative/Punk/Rock; Electronic/Electronic Dance; Latin; hip-hop/Rap; R and B/Soul; Reggae; and Other, which include classical, blues, folk, jazz, and world music.

Levey and Fligor (2011) [23] found that African American, African, and Caribbean participants listened at higher output levels (99.8, 93.4, and 95.1, respectively) [Table 1] while Hispanic, White, and Asian participants listened at relatively lower levels (93.8, 90.5, and 92.6, respectively). An ANOVA showed significant differences among ethnic groups, F (5, 154) = 2.56, P = 0.029. Chi-square tests revealed that African-American participants were significantly more likely than Hispanics and Whites to exceed recommended noise exposure levels (85.7% of African Americans, compared to 65.2% of Hispanic and 36.8% of White participants), χ2 (5, N = 160) =17.46, P = 0.004 [Table 2]. African-American participants were also more likely to exceed recommended weekly noise doses (85.7% compared to 61.5% of Hispanic and 34.2% of White participants), χ2 (5, N = 160) =18.75, P = 0.002. In summary, African American PLD users listened at higher levels and for longer durations than all other ethnic groups.
Table 1: Mean measured PLD output (dBA)

Click here to view
Table 2: Ethnicity: The percentage that exceeded safe listening doses

Click here to view

Levey and Fligor (2011) [23] found that participants across all ethnic groups (African, African American, Asian, Caribbean, Hispanic, and White) who were listening to hip-hop/Rap/R and B/Soul were not listening at significantly higher levels than listeners of the genres that were listened to at the lowest levels ("other" and "electronic" music genres). Chi-squares also confirm that hip-hop/Rap/R and B/Soul listeners in general were not more likely to exceed recommended daily and weekly doses. The absence of a significant effect for music genre was tested in the sample of PLD users consisting only of those who were listening to hip-hop/Rap and R and B/Soul music. In summary, African American PLD users listened at higher levels than White and Hispanic PLD users together. However, it is important to consider why these PLD users might listen louder.

  Discussion Top

The use of PLDs is particularly prevalent among young urban populations. However, it is important to understand why some PLD users actually listen louder than others. One explanation is that PLD users can escape from direct contact with strangers and the noises of the city while at the same time personalizing their listening environment. Bull (2007) [25] reports that this social isolation and personalization results in PLD users feeling calmer during their daily commutes and experiencing more pleasure even during mundane activities. Many PLD users, in fact, describe their iPod® as a necessity, an "urban Sherpa" guiding them through urban life (Bull, 2007). [25] According to the student monitor, college students have rated listening to their iPods® as the coolest free time activity (The Associated Press, 2006). [26] Consequently, it may be difficult to convince PLD users to turn down volume controls, in spite of the risk associated with inappropriate use.

It is also important to explain the finding that African American PLD users listened louder than other ethnic groups. The answer to this question may be found in a cultural analysis of African American listening habits. There is a tradition of loud music in African American culture that has its roots in the American black church, an evangelical tradition of worship through song, dance, and clapping in order to "catch the spirit." The musical tradition in these churches is "loud, vibrant, and energetic," which in turn has spawned a great number of African American R and B/soul artists (Cusic, 1990) [27] (e.g., Ray Charles, Aretha Franklin, James Brown, Janet Jackson, Whitney Houston, and other singers in this music genre). This pattern of playing and listening to loud music is found in other African American musical genres, such as the blues, funk, soul, and rock 'n roll, which emerged out of the black church musical tradition. Salaam (1995) [28] groups these musical genres under the rubric of great black music (GBM). He writes the following (p. 356).

Unlike classical European music, which one contemplates in silence and stillness or in highly structured dance movements, GBM demands response and movement. In a sense, the music does not fully become itself until it literally vibrates its environment and its audience causing both to participate in the music making. Everything from "tearing the roof off the sucker" to "burning down the house," "smoking" and "cooking" or "wreaking maximum effect"-all connote physical transformation of the structure or environment where the music is made.

There may also be a cultural explanation for the finding of higher PLD volume levels specifically for African Americans who listen to hip-hop/Rap/R and B/Soul music. The literature shows that hip-hop music is still one of the most popular musical genres among young African Americans (Cohen 2005). [29] Rose (1994) [24] describes the evolution of sound recording and mixing technology in the 1970s-1980s, allowing rap artists to amplify the bass (a low-frequency sound). "Volume, density, and quality of low-sound frequencies are critical features in rap production" and rap producers use particular equipment because of the sounds they are able to produce in the low frequencies (Rose, 1994, p. 75). [24] Consequently, rap music must be played at a higher volume to be able to fully appreciate the bass.

The "fat sonic boom" esthetic was visible on the streets of New York in the 1970s and 1980s among young African Americans and Latinos who would carry around enormous "boom boxes" or portable tape players on their shoulders and blast them at maximum volume as they walked down the street. This was followed by the evolution of a competitive car culture focused on subwoofers, tweeters and amplifiers designed to produce the loudest sound possible. These portable sound systems demanded the attention of everyone in the vicinity and were part of a culture of listening to music at high levels. Despite a 40% decline in rap CD/vinyl sales in the U.S. since 2000, Blair (2007) [30] reports that hip-hop/Rap/R and B songs continue to dominate top positions on popular file sharing networks as well as most ring-tone downloads. Young African Americans continue to listen to hip-hop/Rap and R and B music in large numbers. Cohen (2005) [29] reports on the results of a survey of 1,600 young African Americans that found that a majority listens to hip-hop every day and 25% watch hip-hop videos every day.

We can speculate that the higher PLD listening levels found for African Americans may be due to the musical preferences as well as the cultural practices of this demographic in relation to music sonority. Importantly, given the differences between ethnic groups in terms of relative risk for NIHL from PLD use, educational efforts should be more intensely focused on young people in the African American community who might be at greater risk of hearing loss due to the tendency to set the volume high when listening to music on their PLDs.

In spite of the findings that African American PLD users listened louder, investigators found lower odds of hearing loss across all frequencies for older African Americans, who were more likely to have normal to mild hearing loss, than older White participants (Lin et al., (2011). [31] This difference was posited on the hypothesis that melanin plays an otoprotective role in noise exposure (Pratt et al., 2009). [32] Melanin is a substance that gives color to the skin, hair, and eye. In humans, those with darker skin have higher amounts of melanin while those with lighter skin have lower amounts of melanin. Some investigators argue that melanin is involved in the structural, metabolic, and vascular health of the cochlea (Barrenas, 1997; Barrenas and Axelsson, 1992). [33],[34] There is ongoing research to investigate the hypothesis that melanin plays a role in the protection of noise exposure.

Guidelines for the prevention of NIHL

Levey et al., (2011) [1] offered guidelines to decrease the number of individuals who may experience NIHL (Fligor, 2006). [2] For example, individuals should not listen to music for longer than an hour and a half at 70-80% at the maximum volume control setting on the portable devices (Portnuff et al., 2011). [22] The average user is able to listen to a player at about 70% of full volume for about 4½ h without increasing NIHL risk (Portnuff et al., 2011). [22] There are also guidelines for the type of earphone used to prevent a NIHL (Fligor and Cox, 2004; Portnuff et al., 2011). [22],[35] Although the output capacity of in-ear or ear bud-style headphones may be higher than over-the-ear or supra-aural headphones (Portnuff et al., 2011), [22] people tend to use their headphones at the same level, if background noise is low (Fligor and Ives, 2006). [36] The primary risk lies in listening to music in noisy environments, with headphone type a secondary concern (Fligor and Ives, 2006; Portnuff et al., 2011). [12],[22] Contrary to popular belief, using in-ear headphones that completely seal the ear allows the user to block out background noise and people often choose to listen at lower levels, even in the high background noise (Fligor and Ives, 2006; Portnuff et al., 2011). [22],[36] In summary, guidelines for the (a) appropriate listening level and duration and (b) appropriate headphone type are necessary to reduce risk for NIHL. Consequently, educational programs in schools, along with effective hearing screenings, are essential to provide the information on the actions necessary to reduce risk for NIHL.

  References Top

1.Levey S, Levey T, Fligor BJ. Noise exposure estimates of urban MP3 player users. J Speech Lang Hear Res 2011;54:263-77.  Back to cited text no. 1
2.Fligor BJ. "Portable" music and its risk to hearing health, 2006. Available from: http://www.hearingreview.com/issues/2006-03.asp. [Last accessed on 2012 Jun 30].  Back to cited text no. 2
3.Peng JH, Tao ZZ, Huang ZW. Risk of damage to hearing from personal listening devices in young adults. J Otolaryngol 2007;36:181-5.  Back to cited text no. 3
4.Weichbold V, Zorowka P. Can a hearing education campaign for adolescents change their music listening behavior? Int J Audiol 2007;46:128-33.  Back to cited text no. 4
5.National Institute on Deafness and Other Communication Disorders. Noise-Induced Hearing Loss (NIH Publication No. 97-4233). Bethesda, MD: NIDCD Fact Sheet; 2007.  Back to cited text no. 5
6.Henderson D, Bielefeld EC, Harris KC, Hu BH. The role of oxidative stress in noise-induced hearing loss. Ear Hear 2006;27:1-19.  Back to cited text no. 6
7.Martin GY, Martin WH. The Jolene cookbook. Portland, OR: Oregon Health and Science University; 2007. Available from: http://www.dangerousdecibels.org/jolene/cookbook/. [Last accessed on 2012 June 30].  Back to cited text no. 7
8.Rawool VW, Colligon-Wayne LA. Auditory lifestyles and beliefs related to hearing loss among college students in the USA. Noise Health 2008;10:1-10.  Back to cited text no. 8
[PUBMED]  Medknow Journal  
9.Hoover A, Krishnamurti S. Survey of college students' MP3 listening: Habits, safety issues, attitudes, and education. Am J Audiol 2010;19:73-83.  Back to cited text no. 9
10.Vogel I, Brug J, Van der Ploeg CP, Raat H. Adolescents risky MP3-player listening and its psychosocial correlates. Health Educ Res 2011;26:254-64.  Back to cited text no. 10
11.McNeill K, Keith SE, Feder K, Konkle AT, Michaud DS. MP3 player listening habits of 17 to 23 year old university students. J Acoust Soc Am 2010;128:646-53.  Back to cited text no. 11
12.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;115:861-7.  Back to cited text no. 12
13.Quintanilla-Dieck Mde L, Artunduaga MA, Eavey RD. Intentional exposure to loud music: The second MTV.com survey reveals an opportunity to educate. J Pediatr 2009;155:550-5.  Back to cited text no. 13
14.Keith SE, Michaud DS, Chiu V. Evaluating the maximum playback sound levels from portable digital audio players. J Acoust Soc Am 2008;123:4227-37.  Back to cited text no. 14
15.Airo E, Pekkarinen J, Olkinuora P. Listening to music with earphones: an assessment of noise exposure. Acustica 1996;82:885-94.  Back to cited text no. 15
16.Montgomery JK, Fujikawa S. Hearing thresholds of students in the second, eighth, and twelfth grades. Lang Speech Hear Serv Sch 1992;23:61-3.  Back to cited text no. 16
17.Blair JC, Hardegree D, Benson PV. Necessity and effectiveness of a hearing conservation program for elementary students. J Educ Audiol 1996;4:12-6.  Back to cited text no. 17
18.Niskar A, Kieszak S, Holmes A, Esteban D, Rubin C, Brody D. Estimated prevalence of noise-induced hearing threshold shifts among children 6-19 years of age. The third national health and nutrition examination survey, 1988-94. U S Pediatr 2001;108:40-3.  Back to cited text no. 18
19.Zogby J. Survey of teens and adults about the use of personal electronic devices and head phones, 2006. Available from: http://www.nsslha.org/NR/rdonlyres/10B67FA1-002C-4C7B-BA0B-1C0A3AF98A63/0/zogby_survey2006.pdf. [Last accessed on 2012 Aug 22].  Back to cited text no. 19
20.Torre P 3 rd . Young adults' use and output level settings of personal music systems. Ear Hear 2008;29:791-9.  Back to cited text no. 20
21.Hodgetts WE, Rieger JM, Szarko RA. The effects of listening environment and earphone style on preferred listening levels of normal hearing adults using an MP3 player. Ear Hear 2007;28:290-7.  Back to cited text no. 21
22.Portnuff CD, Fligor BJ, Arehart KH. Teenage use of portable listening devices: A hazard to hearing? J Am Acad Audiol 2011;22:663-77.  Back to cited text no. 22
23.Levey S, Fligor BJ. Noise exposure while listening to portable music players. Poster Presented at a Meeting of the American Speech-Language-Hearing Association, San Diego, CA; 2011.  Back to cited text no. 23
24.Rose T. Black Noise: Rap Music and Black Culture in Contemporary America. Middleton, CT: Wesleyan University Press; 1994.  Back to cited text no. 24
25.Bull M. Sound Moves: iPod Culture and Urban Experience. The International Library of Sociology, London: Routledge; 2007.  Back to cited text no. 25
26.The Associated Press. Survey: iPods More Popular than Beer. Available from: http://www.washingtonpost.com. [Last retrieved on 2006 Jun 8].  Back to cited text no. 26
27.Cusic D. The Sound of Light: A History of Gospel Music. Bowling Green, OH: Bowling Green State University Press; 1990.  Back to cited text no. 27
28.Salaam K. It didn't jes grew: The social and aesthetic significance of African American music. Afr Am Rev 1995;29:351-75.  Back to cited text no. 28
29.Cohen CJ. Black Youth Culture Survey, 2005. Black Youth Project. Available from: http://www.blackyouthproject.com. [Last accessed on 2012 Aug 22].  Back to cited text no. 29
30.Blair E. Is Hip Hop Dying or Has It Moved Underground? 2007. National Public Radio program, Aired on March 11, 2007. Available from: http://www.npr.org/templates/story/story.php?storyId=7834732. [Last accessed on 2012 Aug 22].  Back to cited text no. 30
31.Lin FR, Thorpe R, Gordon-Salant S, Ferrucci L. Hearing loss prevalence and risk factors among older adults in the United States. J Gerontol A Biol Sci Med Sci 2011;66:582-90.  Back to cited text no. 31
32.Pratt SR, Kuller L, Talbott EO, McHugh-Pemu K, Buhari AM, Xu X. Prevalence of hearing loss in black and white elders: Results of the cardiovascular health study. J Speech Lang Hear Res 2009;52:973-89.  Back to cited text no. 32
33.Barrenäs ML. Hair cell loss from acoustic trauma in chloroquine-treated red, black and albino guinea pigs. Audiology 1997;36:187-201.  Back to cited text no. 33
34.Barrenäs ML, Axelsson A. The development of melanin in the stria vascularis of the gerbil. Acta Otolaryngol 1992;112:50-8.  Back to cited text no. 34
35.Fligor BJ, Cox LC. Output levels of commercially available portable compact disc players and the potential risk to hearing. Ear Hear 2004;25:513-27.  Back to cited text no. 35
36.Fligor BJ, Ives TE. Does headphone type affect risk for recreational noise-induced hearing loss? Presented at the NIHL in Children Meeting, Cincinnati, OH. Lay-paper. Available from: http://www.hearingconservation.org/docs/virtualPressRoom/FligorIves.pdf. [Last accessed on 2006 Oct 19].  Back to cited text no. 36

Correspondence Address:
Sandra Levey
Department of Speech Language Hearing Sciences, Lehman College, The City University of New York
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1463-1741.116553

Rights and Permissions


  [Table 1], [Table 2]