search for: 140hz

Hi, But in fact, it really affects the voice quality. One of my tester says, "Is your mouth far way from the mic?" Could you explain why we should cut 200hz below? >The notch filter is specifically designed to cut below 200 Hz when >working in narrowband. In wideband, the cutoff is more around 50 Hz. The >reason is that in narrowband operation (irrespective of the

...nto using coarse steps, so the more interesting energy in the middle of the voice band is coded with those coarse steps - i.e. poorly. Low bit rate codecs, like G.729 or speex, usually apply their own fast rolloff filter for low frequencies - e.g. G.729 rolls off its input hard, with a turnover at 140Hz - their whole coding methodology tends to break down without that. The telephone network normally rolls off hard below about 300Hz, so this actually perfectly normal voice for a phone call. A second reason to remove the bass frequencies is if you don't you can get nasty echoes if the audio is...