Premodulation Speech Clipping and Filtering: a Consideration of Their Effects on the Intelligibility of Speech
Abstract
Speech clipping and filtering circuits in voice communication systems so distort the transmitted speech as to raise a question of their effect on intelligibility. Results of several experiments indicate that speech clipping alone improves intelligibility when signals are partially masked by electrical noise entering the system between transmitter and receiver. Signals which are not so masked are similarly affected to almost the same degree. Intelligibility improves as clipping increases up to at least 24 db. Under extreme noise masking, very heavy clipping (100 db or more) improves intelligibility, but reduces intelligibility of signals not so masked. Other experiments show that intelligibility is not likely to suffer when voice frequencies below 580 cycles are sharply attenuated, with the possible exception that when masking white noise is very intense, restoring low frequencies causes a slight increase of intelligibility. Attenuating frequencies above 3900 cycles has no significant effect on intelligibility; however, reducing the low-pass cut-off point to 2500 cycles does lower intelligibility considerably. It is suggested that band-pass filtering limits be 600 to 4000 cycles. A list of references is appended.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 14, 1950
- Accession Number
- AD0663600
Entities
People
- Stephen E. Stuntz