Page 42 - Fall2019

“The New Secondhand Smoke”
Of the three auditory disorders, only hearing loss is well understood (Cunningham and Tucci, 2017. Tinnitus is commonly called ringing in the ears but technically is the perception of sound for which there is no external auditory stimulus (Bauer, 2018). Hyperacusis is a sensitivity to noise in which noise levels that don’t affect most people are per- ceived as uncomfortable or actually painful (Baguley, 2003). People with hyperacusis often describe noise as being like a needle stuck in the ear. The most severely affected hyperacu- sis patients have difficulty leaving their homes, and when they do, they wear both earplugs and earmuff hearing protection.
Auditory disabilities are invisible and underappreciated. Unlike the blind, who have difficulty living independently, people with hearing loss have no problem walking or driving, shopping, preparing food, or traveling. People with hearing loss can compensate for their disability by asking someone to repeat something, cupping a hand to the ear, or seeking out quiet spaces in which to converse (Fink, 2017b). Despite this, hearing loss causes major problems in social function, leading to isolation, depression, and other problems.
There are ADA protections for the deaf and for those with profound hearing impairment (>81-90 dB decrement), including workplace modifications to allow gainful employ- ment and mandated auxiliary aids and services, such as fire alarms with strobe lights, teletype communication devices, and sign language interpreters when needed (US Department of Justice, 2010). However, there are no ADA Access Guide- lines for those with only mild (25-40 dB), moderate (41-60 dB), or severe (41-80 dB) hearing loss, and no ADA standards for ambient-noise levels in places of public accommodation (US Access Board, 2002).
High ambient-noise levels have a disproportionate impact on older people due to their high prevalence of hearing loss. Half of those over 65 and 80% of those in their 80s have at least 25-40 dB hearing decrements (Lin et al., 2011). Many older people live alone, and a restaurant meal may be the only time they converse with others.
For a variety of reasons, hearing aids do not help users under- stand speech in noisy places as much as desired because they primarily increase audibility but do not improve intelligibil- ity (Lessica, 2018). As a consequence, people with hearing loss need lower ambient-noise levels to be able to understand speech. The technologies for reducing and controlling noise have been known for more than half a century. These include
designing mechanical devices to be quieter or isolating, insu- lating,reflecting,deflecting,orabsorbingthesound(Beranek, 1960). For the built environment, noise control techniques are also well understood (Harris, 1994). Relatively inexpen- sive items such as ceiling panels, wall hangings, carpets, and draperies can help control noise and reduce reverberation. Restaurant acoustics are reviewed by Roy and Siebein (2019). The simplest environmental modification costs nothing: turn-
ing down the volume of amplified sound.
Reducing ambient-noise levels will likely require govern- mental action. Laws and regulations could specify a decibel level or a functional measure, perhaps requiring indoor sound levels low enough to allow people to converse without straining to speak or to be heard. This is approximately 70-75 dB(A) for those with normal hearing and near 60 dB(A) for those with hearing loss. With appropriate enabling legislation, crowd-sourced smartphone applications, such as iHEARu (ihearu.co) and SoundPrint (soundprint.co), could provide data for local communities to initiate enforcement actions against noisy establishments.
Noise Exposure Above a 70 Decibel Time-Weighted Daily Average Will Cause Hearing Loss
The only evidence-based safe noise exposure level to prevent
hearing loss is 70 dB time-weighted average for 24 hours [LAeq(24)], not the 85 dB(A) occupational exposure level (Fink, 2017a). Occupational exposures occur 8 hours a day, 240 days a year at work, for 40 years. (NIOSH, 1998) Noise is different from other occupational exposures such as ionizing radiation or toxic solvents because exposure continues out- side the workplace, all day long, all year long, for an entire lifetime. The EPA (1974) adjusted the NIOSH-recommended exposure level (REL) for 24-hour daily exposure, 365 days a year, to calculate the daily 70 dB time-weighted average safe noise exposure level to prevent hearing loss. The EPA document carefully states that this is not an official regula- tion or standard.
The 70 dB daily average [LAeq(24) = 70] is probably too much noise exposure to prevent hearing loss. The EPA adjusted the REL for additional daily and annual exposure time but not for lifetime exposure. In 1967, life expectancy for a man was only 67 years. With male life expectancy now approaching 80 years in the United States, adjustment for the additional years of exposure is needed. The additional years of exposure are among the factors explaining why hearing loss is so prevalent in older people (Anderson et al., 2018).
42 | Acoustics Today | Fall 2019