摘要： Understanding the noise characteristics for finding appropriate filtering technique/s so as to obtain sufficiently
clear speech samples for Speaker Identification, is one of the challenging tasks in Forensic Acoustics. Speaker's
idiosyncratic speech should not be affected when the noise reduction is carried out; otherwise, Speaker Identification
becomes highly erroneous. We have collected fifty noisy speech samples reported to be recorded in different modes from
actual crime cases received in the laboratory. The samples are analyzed after subjecting to various filtering techniques and
compared with the clear speech mixed with the noise collected from non-speech portion. Distortion levels on the speech
are studied at various stages of application of filters in terms of SNR and Speaker Specific Information. Retaining the
Speaker Specific Information as primary concern of our study, the limitation of filtering techniques depending on the
characteristic and intensity level of noise is worked out for noisy speech samples. Subsequently a statistical study is also
conducted. Listening tests were conducted to ensure that the perceptual features of the original noisy speech are preserved
while applying filters. This work demonstrates the efficiency of Noise reduction filters in improving SNR and their
controlled applications for preserving Speaker dependent features depending on the various noise characteristics
embedded on speech samples.
