Hearing loss after 3 years of exposure is less likely than after 45 years. However the proportion is greater than simply dividing the amount of hearing loss pro rata. To a rough approximation, the magnitude of NIHL after 3 years is 43% of the NIHL after 45 years.

Source: SCENIHR,  Potential health risks of exposure to noise from personal music players and mobile phones including a music playing function (2008) , Section 3.5.3., Page 28.

Personal Music Players & Hearing

Figure 1*: Normal equal-loudness-level contours for pure tones under free-field listening conditions

Figure 2: The prevalence of hearing impairment

Figure 3: Estimated units sales in EU of all portable audio devices and MP3 devices over the period 2004–2007,

Figure 4: The number of unit sales for all portable audio devices for the ten countries and for the EU,

Figure 5: Number of unit sales (in thousands) for CD and MP3 devices in ten European countries* between 2001 and 2007

Figure 6: Cumulative numbers of MP3 players and all portable audio equipment in the EU

Figure 7: Percentage of each portable audio device sold in 2004-2007

Figure 8: Percentage of each portable audio device sold in 2007 and the estimated number of units sold in EU

Table 1: Examples of sound pressure levels in relation to hearing threshold and pain threshold (in dB SPL)The range of human ear’s audible sounds goes from 0 dB SPL (hearing threshold) to 120-140 dB SPL (pain threshold)

Table 2: Audiometric hearing thresholds of normal ears: conversion of dB SPL into dB HL (Extracted from ISO, 2003) Pure-tone audiometric thresholds are expressed in dB HL (hearing level). The differences between dB HL and dB SPL, arise from isophonic curves.

Table 3: The examples of equivalent time-intensity levels referred to the action levels according to the Directive 2003/10/EC

Table 4: World Health Organisation Grades of Hearing Impairement (WHO, 2008)

Low and high-pitched sounds appear less loud to the human ear

EU Action levels for noise protection at work

Table 5: Noise Induced Hearing Loss (NIHL) predicted from ISO 1999 as a function of noise exposure level for 45 years (adapted from Lutman et al. 2008) Extent of hearing loss to be expected from a working lifetime of 45 years at daily continuous noise levels of 80, 85, 90 and 95 dB(A).

Table 6 : Noise Induced Hearing Loss (NIHL) predicted from ISO 1999 as a function of noise exposure level for 3 years (adapted from Lutman et al. 2008) Extent of hearing loss to be expected from a shorter exposure duration of 3 years at daily continuous noise levels of 80, 85, 90 and 95 dB(A).