In a tunnel on an express-way, emargency telephone boxes are settled
to keep speech quality of a near-end talker from ambient noises.
When the talker opens the door to confirm
an accident situation, the telephone box cannot reduce the noise.
We have developed a real-time noise suppressor
for high-level noises in a tunnel.
| 
|
Speech and noise waveforms are shown in the figure.
We can predict a present speech from past speech samples.
But, noise prediction is difficult.
We employ a linear predictor which gives only predictable signals.
| 
|
We implement the linear predictor onto a DSP (Digital Signal Processor).
Noise reduction results show that the proposed real-time noise suppressor is applicable fora high-level tunnel noise environment.
|

Waveform of noise reduction results

Spectrogram of noise reduction results
Sound Data
Observe Signal
Output of Conventional Method
Output of Proposed Noise Method
|