Acoustic handset for telephone receiver designed to give voice feed-ba - designed to give voice feed-back with digital systems

摘要

The person speaking into a telephone handset is given feed-back of his own voice to prevent him from speaking too loudly. With analogue systems this is provided by various means including the leakage associated with hybrid transformers and their line balancing. When digital telephony is used, these hybrids are not necessary and the cross-talk is unintelligible. This receiver uses a hollow handset with an acoustic passage linking the mouthpiece to the earpiece. The passage is designed to ensure that the relation of the acoustic pressure at the output to the input is -20dB at IkHz and has an attenuation slope of 20dB per octave.