Mapping the link between Noise
Pollution and Hearing Damage
We developed the world hearing index as a natural expression of our Mimi commitment to helping the world hear, and personalise sound better. We’ve found that the average city dweller has a hearing loss equivalent to 10-20 years older than their actual age. With the urban population projected to grow by 1.85% per year between 2015 and 2020, an increasingly large population will be exposed to the detrimental effects noise pollution on hearing ability.
For World Hearing Day on March 3rd, we created the Worldwide Hearing Index in order to draw attention to this global issue. We analyzed data from our Mimi hearing test app, the largest, digital database that tracks people’s hearing ability—and we paired this data with research from the World Health Organization (WHO) on noise pollution in 50 cities internationally.
While vision tests are routine for most, hearing exams are not. This is a concern as the earlier hearing loss is detected, the better the chances are for preventing further damage.
Dr. Manfred Gross of Charité University Hospital, Berlin
World Hearing Loss: City Ranking
Male Hearing Loss: The average difference between a male’s actual age and hearing age (additional average hearing age) per city, via Mimi hearing tests. Female Hearing Loss: The average difference between a female’s actual age and hearing age (additional average hearing age) per city, via Mimi hearing tests. Average Hearing Loss: The additional average hearing age a citizen in each city was found to have, via Mimi hearing tests. Hearing Loss Rank: This is the average hearing loss represented proportionately from 0-1 Noise Pollution Rank: This shows noise pollution represented proportionately from 0-1 Combined Hearing Loss Rank: The sum of the Hearing Loss Rank and Noise Pollution Rank.
Click column header to filter the table by each criterion
The Mimi data, collected from over 200,000 hearing tests worldwide, presents the difference between a participant’s actual age and their hearing age. The hearing age reflects the age of the participant’s hearing ability and is calculated via the hearing test undertaken within the Mimi app. The difference between the actual age and hearing age of a participant is presented as a figure, representative of hearing age years additional to the participant’s actual age.
For example, the Average Hearing Loss in Zurich is +10.63 years, meaning a citizen in Zurich has a hearing ability of an individual 10.63 years older than themselves. The Average Hearing Loss statistic was further broken down into males versus females.
The Average Hearing Loss for each city was ranked from 0-1, with 0 assigned to the city with the lowest Average Hearing Loss, and 1 for the city with the highest. The noise pollution levels from each city were ranked in the same way. These two statistics were combined to create the Combined Hearing Loss Index, the figure by which the results are ranked.
The Average Hearing Loss result was found to have a 64% positive correlation with noise pollution levels in each city, indicating hearing loss may be a direct or indirect outcome of living in these cities.
We hope that the study will not only raise awareness among residents of noise polluted cities, and their governing institutions, but that it will act as a call to action for individuals and health care providers to make better investments concerning aural health.
Chief Physician, Clinic for Audiology and Phoniatry, Charite University Clinic Berlin
We used data gathered from the digital Mimi hearing test app which allows participants to enter their age, sex and to test their hearing age. The hearing age is calculated under the ISO 7029 Standard 1999:2013, Acoustics: Estimation of noise-induced hearing loss, ICS:12.140, (2013).The location of the participants was determined via their geolocation. From this database, we selected 50 cities where enough data was available to form a representative sample, thus, cities without sufficient data were not included in the study.
From the available data, we looked at the Hearing Loss of the user, HL, or, defined as:
Thus, a negative value of HL, or a small absolute HL but high Hearing Age and Age, implies that the user is presenting hearing loss. This number represents the absolute value of the difference between a user’s actual age and their hearing age. Based on this number we ranked these results for both male and female. We calculated the average HL between genders. Based on these results we extrapolated a HL for each of the 50 cities. The data is normalized within the sample by representing the HL of the city from 0-1. (0: min, 1: max).
We then collected data from the World Health Organization and SINTEF report on noise pollution and ranked the cities within the samples to form the Noise Pollution indicator (NP). This data was also normalized within the sample by representing the noise pollution of the city from 0-1. (0: min, 1: max).
Each city’s score on the World Hearing Index is defined as the sum of these two indicators. This value allows us to understand how each city on the index performs in terms of these two factors in comparison to the others on the list.