ed microphones are better than acoustic tubes and creased versatility and a greater choice of headsets. essential in noisy environments. Under-the-chin headsets don't disturb the hair. Over-the-head style headsets are stable and more robust. Contour 'on-the-ear' style 58.15 Headset approval process headsets are light, less noticeable. Conversion kits are an important new cost development and allow users to experiment with both over-the-head and on-the-ear styles to decide their preferences. In terms of approvals, much depends upon the telephone system that Over-the-ear pads are comfortable, won't cause infection and block the headset is to be used with, and it is frequently the OEM who out some external sound. In-the-ear tips offer high close acoustic obtains the required approval, under DTI specification 85/013. coupling. Some people find the tips uncomfortable, irritating and The approval process is a lot easier nowadays since the introduc- unhygienic. tion of the BABT simple attachment scheme. Previously, testing The environment is all important. In hot climates, ears sweat. was carried out under the direct control of BABT and, in the event Vinyl ear pads can be wiped clean with a sterilising pad, while foam of failure, the modified apparatus had to repeat the entire test pads absorb perspiration and need replacing regularly. procedure, at considerable expense. Under the new arrangement, Is the office noisy? Does it lack acoustic damping, are the surfaces testing is carried out directly with one if the accredited test houses hard, is there a lot of paper shuffling? In particularly noisy environ- who then submit their report to BABT. Testing, and charging, is ments, noise cancelling microphones are available but they must be carried out until a failure occurs or the test is completed. In the event positioned properly for optimum performance. If not, their use can of a failure, the test house informs the designer who can then take be counter productive. the equipment away, rectify it and bring it back to continu