Survey of chemical substances in headphones and hearing protection aids
4 Description of the product groups
The product groups being examined in the project are in general described as “Headphones” and “Hearing protection aids”. In practice, these overall descriptions cover a wide range of products with large differences in both mode of operation, design and selection of materials.
4.1 Headphones
Regarding headphones there is a differentiation between the following basic subtypes:
”Around-ear” headphones which are the well-known, ”old-fashioned” type where a loudspeaker is contained in a cup which encircles the ear and thus shut out external noise. The cups are kept in place by an elastic spring band over the head. There are only a few variations in the basic appearance but large differences in the choice of materials for the individual components. A number of models are shown in Figure 1.
Figure 1. Around-ear headphones – different models
”On-ear” headphones, where the loudspeaker is protected by pads sitting outside on the ear. The loudspeaker unit which can be of different size is held against the ear in different ways, e.g. by using spring bands over the head, behind the neck or around the ear. Thereby, the headphones become comfortable to use in different situations, e.g. during exercise of sports. Figure 2 shows three different models.
Figure 2. On-ear headphones. From left with a spring band over head, behind the neck and around the ear.
”In-ear” headphones are small loudspeakers which are placed directly in the ear and may be held in place by a spring band over head, around the neck or around the ear. The loudspeakers may be embedded in hard plastic which has a soft layer of foam or rubber on the outside, if necessary, but they can also be embed in a soft plastic which adapts itself to the shape of the ear when the plugs are placed.
Figure 3. In-ear headphones. From left a model with a spring band, a model with soft material which adapts itself to the shape of the auditory canal and a model that is individually adapted.
Alternative products and technologies. During the recent years a significant development within fields of application, product design and technology has taken place. Within the field of application, especially headsets being used in connection with e.g. the use of a PC can be pointed out. Besides one or two loudspeakers (in general of the On-ear type), the headset consists of a microphone which makes it possible for the user to communicate interactively with the outside world, e.g. in connection with IP telephony or when the computer is used for games in a network (Figure 4). Another field of application in rapid development is hand-free mobile telephony where the user via a loudspeaker (generally of the In-ear type) and an external microphone can use a telephone with very little use of the hands.
Within the field of technology it is especially worth pointing at the Bluetooth technology providing that audio signals are transferred to the loudspeakers without used of a cord. On the other hand it is necessary to provide the headphones with a receiver which is in direct connection with the loudspeakers. This receiver can be integrated in Around-ear and On-ear models, without being visible, while with In-ear models it is often necessary to use a spring band around the ear to keep the receiver unit in place (Figure 4).
The mentioned tends of development are not assessed to have any influence on the basic design of the headphones or on the choice of materials for these.
Figure 4. Examples of a headset and a bluetooth receiver with In-ear loudspeaker
4.2 Hearing protection aids
The product group hearing protection aids is somewhat less differentiated than headphones. Thus, there are only two subgroups, Around-ear and In-ear, as an On-ear product will not be able to fulfil the primary function, to lower the external noise to an acceptable level.
With regard to appearance and materials hearing protection aids look like headphones. Some hearing protection aids have also a sound source so at the same time the user has the possibility of listening to the radio or receiving messages via a wireless system while the external noise is shut out. The two basic types of hearing protection aids are shown in Figure 5.
Figure 5. In-ear and Around-ear hearing protection aids
A subgroup of In-ear hearing protection aids is ear plugs which may be assumed to fulfil the same basic performance as In-ear hearing protection aids but are not adapted to the individual user. This subgroup is mapped in a former survey project from 2003 with two part reports, Consumer project report no. 27 (Surveying of chemical substances in earplugs. Phase 1: Collection of earplugs) and no. 28 (Mapping of chemical substances in earplugs. Phase 2: Analysis of substances), respectively. In these reports basic materials and a number of additives in ear plugs were surveyed based on inquiries to producers, importers and retail trade, followed by an analysis of selected products. The subgroup is not considered further in this survey project but the results will be included where relevant.
4.3 Legislation within the area
According to chief consultant Leif Christensen from the Danish Trade Organisation for Consumer Electronics headphones are covered by the WEEE directive (Waste from Electric and Electronic Equipment, Directive 2002/96/EC) and the RoHS directive (Restriction of the use Of certain Hazardous Substances, Directive 2002/95/EC) (Leif Christensen, personal communication, 17/6-07). The RoHS directive includes a ban on the use of lead, mercury, cadmium, hexavalent chromium, polybrominated diphenyl ethers (”PBDE”, penta-BDE, octa-BDE and deca-BDE) and polybrominated biphenyls in electrical and electronic equipment from 1 July 2006. There are a number of exceptions from the bans in the RoHS directive, e.g. lead in certain types of soldering materials is temporarily permitted. Furthermore, the EU Commission has lifted the ban on deca-BDE for application in polymers (cf. the decision of the Commission dated 13 October 2005). Denmark has taken legal proceedings against the European Court of Justice with the intention to have this decision cancelled.
Products, for which the RoHS directive does not apply, are regulated by the Danish legislation regarding restrictions on the use of the heavy metals lead, mercury and cadmium. This means that these regulations will apply to hearing protection aids. The following legislation is relevant:
- Statutory Order on ban on import and sales of products containing led. Stat. Ord. 1012 of 13.11.2000.
- Statutory Order on ban on import, sales and export of mercury and mercurial products. Stat. Ord. 627 of 01.07.2003.
- Statutory Order on ban on sales, import and production of cadmium-containing products. Stat. Ord. 1199 of 23.12.1992.
Leif Christensen from BFE also assesses that the EuP Directive (Eco-design of Energy-using Products (EuP), Directive 2005/32/EC) apply to wireless headphones with a power supply in the form of a battery.
Products with radio equipment must also keep the requirements in the R&TTE Directive for radio and teleterminal equipment (1999/5/EC).
Finally it can be mentioned that a number of hearing protection aids are equipped with different kinds of radio communication and/or other means of playing music. Therefore they are comprised by the same directives which apply for headphones.
Version 1.0 April 2008, © Danish Environmental Protection Agency