Selection criteria for call centre headsets

Project No. BIA 4102


completed 06/0003


Headsets are the most important item of equipment for call centre employees. Their acoustic and ergonomic characteristics are crucial to the performance and sense of well-being of their wearers. The ambient sound experienced by call centre staff and the speech signal over the headset are the factors determining comprehensibility of speech. Call centre operators and staff require assistance in the assessment of the headsets' transmission characteristics. The comfort for the wearer is determined by the ergonomic wear comfort characteristics of the headsets. At the present time, call centre operators do not have adequate, suitable aids for assessing the transmission and wear comfort characteristics. In order to prevent hearing loss, headsets employed in other working areas (e.g. noise zones) are equipped with sound level limiters. Whether limitation of the sound level is inherently necessary or beneficial for call centre headsets was to be established. The development of assessment criteria for call centre headsets within the scope of this project is also intended to enable the aspects referred to here to be considered during their selection.


Experience has shown technical data to be unsatisfactory as the sole criterion for headset selection. Suitable questionnaires were therefore first drawn up concerning speech intelligibility, the transmission characteristics of the headsets, and their ergonomic wear comfort characteristics. For this purpose, headsets were grouped according to the results already available from laboratory measurements (see Project 0066, "Analysis and improvement of the working conditions in call centres" by the BG Institute for Occupational Safety and Health (BIA)). One headset from each group was tested by staff in call centres, who then assessed it with the aid of the questionnaires. A high staff density and small rooms, high conversation component and poor room acoustics give rise to a high background sound level. Conversely, low staff density and large rooms, a low conversation component and favourable room acoustics provide a sound basis for pleasant and efficient working. In order for valid results to be obtained, call centres were selected for the survey and divided into three categories (low, medium and high background sound level) which were considered representative in terms of the conditions stated for call centres. In order for the need for sound level limiters on headsets to be assessed, measurements of the background sound and of the sound level experienced by the staff (background sound and speech signal through the headset) were performed in 10 to 12 call centres with medium and high background sound levels. At the same time, parameters for objective assessment of speech intelligibility were identified in accordance with DIN EN ISO 9921, "Ergonomics - Assessment of speech communication" for those workplaces for which corresponding measurements of the spectra were available.


Based upon the results of the field study conducted with three different types of headset and for two different sound pressure levels (51-55 dBA and 56-60 dBA), a list of key information was drawn up for the selection of call centre headsets. In view of variation in individual requirements, it is essential that each employee be given a choice of more than one headset. Important criteria for a satisfactory headset are a good fit and the weight of the headset, and also the type and dimensions of the ear pads. The study also showed that uncertainty regarding the use of the equipment can be avoided if call centre agents are provided with detailed instruction in operation of the headset and the telephone system as a whole.

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Financed by:
  • Hauptverband der gewerblichen Berufsgenossenschaften (HVBG)
  • Berufsgenossenschaft der Banken
  • Versicherungen
  • Verwaltungen
Research institution(s):
  • Berufsgenossenschaftliches Institut für Arbeitsschutz - BIA


Type of hazard:



Lärm, Ergonomie, Stress

Description, key words:

Call centre, headset, headset selection, transmission characteristics, speech intelligibility, wear comfort characteristics, ergonomic design, consultation of headset users, STI index