Abstract: An earpiece comprising an earbud, which is arranged such that it may be inserted into the ear canal of a user, and a housing, which houses at least one microphone that is arranged to sample the ambient environment, the housing comprising a port through which sound may be received by the microphone, the earpiece being arranged such that when the earbud is inserted into the ear canal of a user the microphone samples the ambient environment between the earpiece and the concha.

Abstract: A headset apparatus having a headwear member (9) e.g. an ear shell, possessing a surface formation to which a separate attachment device (1) is reciprocally shaped to attach by a push-fit (e.g. by sliding, slotting or clipping) into engagement with the surface formation. In this way the attachment means may be fitted to the surface formation on the headwear member without requiring the use of through-holes passing through the body of the headwear member.

Abstract: A headset apparatus having a headwear member (9) e.g. an ear shell, possessing a surface formation to which a separate attachment device (1) is reciprocally shaped to attach by a push-fit (e.g. by sliding, slotting or clipping) into engagement with the surface formation. In this way the attachment means may be fitted to the surface formation on the headwear member without requiring the use of through-holes passing through the body of the headwear member.

Abstract: A headset apparatus having a headwear member (9) e.g. an ear shell, possessing a surface formation to which a separate attachment device (1) is reciprocally shaped to attach by a push-fit (e.g. by sliding, slotting or clipping) into engagement with the surface formation. In this way the attachment means may be fitted to the surface formation on the headwear member without requiring the use of through-holes passing through the body of the headwear member.

Abstract: A telephone communication method provides simultaneous duplex channels between respective pairs of stations over a single wire pair highway by frequency division multiplexing. Each duplex channel has a predetermined pair of carrier frequencies, but only carrier frequency pairs of channels in use for communication are present in the highway at any time. On initiating a call, a station seeks for a free channel and reserves it by generating the "go" carrier of the free channel modulated with the call sign of the desired station, and also generating an alert signal. Quiescent stations respond to the alert by seeking a "go" carrier with call sign data and, on identifying their own call sign, generating the corresponding return carrier to set up the channel.