Spectral Subtraction and Pitch Enhancement Methods for Electrolaryngeal Speech.
Nagel, George Steven.
- The larynx is a crucial organ for normal speech production. However, every year approximately five thousand patients are diagnosed with laryngeal cancer and undergo a total laryngectomy resulting in the removal of their entire larynx. Without the larynx, these patients are unable to produce speech through conventional means and many use an artificial larynx, also called an electrolarynx (EL), to o... read moremmunicate. ELs are battery operated handheld devices which transmit a pulse train the user's neck where the sound may be modulated into speech. They are commonly selected as a method of voice restoration due to their portability and ease of use. However, EL devices have many qualities which result in the speech being unnatural and unintelligible. Two of the qualities which contribute most to the unnatural and unintelligible nature of EL speech are the lack of accurate frequency variation and the irradiated noise from the device. Of the devices currently available, most provide little or no opportunity to vary pitch or provide a method of pitch variation which does not allow for pitch contours similar to those found in normal speech. Additionally, due to the nature of their construction, irradiated noise is found in all EL devices. This research focuses on a method of improving the control of the fundamental frequency of the device and methods of reducing the irradiated noise from the device.read less